NASA Ocean Vector Wind Science Team Meeting · 2009-06-05 · NASA Ocean Vector Wind Science Team Meeting Click here to view a list of all the participants Click here to go back Displaying

NASA Ocean Vector Wind Science Team Meeting

Click here to view a list of all the participants

Click here to go back

Displaying 3 results per page.

<< [1] >>

TitleContact

InformationOther Authors

Abstract

TypeCategory Abstract Remove

Mulit-

Satellite

Gridded

Ocean

Surface

Wind

Product

Florida State

University/COAPS

Mr. Paul Hughes

Center for Ocean-

Atmosphere

Prediction Studies,

Florida Statue

University

200 RM Johnson

Bldg.

Tallahassee, FL

32306-2840

United States of

America

[email protected]

Mark A. Bourassa

(Florida State

University/COAPS)

Contributed

Poster

New

products

The ocean, covering roughly

71% of the Earth’s surface, plays a

major role in driving both regional

and global climate variability via the

exchange of heat, moisture,

momentum, gases, and particulate

matter across the air-sea interface.

The fluxes of energy and matter

exhibit variability on multiple

temporal scales, thus in order to

better understand the coupled

climate system the ocean surface

variables need to measured on

scales ranging from intradaily to

interdecadal and beyond. To

accurately represent phenomena on

subdaily temporal scales,

information from multiple orbiting

satellites is required. This study

attempts to objectively construct a

global high resolution multi-satellite

blended ocean surface wind (speed

and direction) product using data

obtained from the Remote Sensing

Systems (RSS). A direct

minimization approach is

implemented with the University of

Washington Planetary Boundary

Layer (UWPBL) model acting as a

physical constraint. The UWPBL

model will address the issue of

having significantly less vector than

speed data by physically relating the

vector and scalar wind speed. The

ultimate goal is to improve upon the

existing spatiotemporal resolution

and reduce the need for smoothing

allowing smaller scale features and

sharp gradients to be better

remove

10/09/2008 Displaying Abstracts

http://coaps.fsu.edu/scatterometry/m… 1/78

sharp gradients to be better

resolved.

Title Contact InformationOther

Authors

Abstract


Ocean

Precipitation

Measurements

using

SeaWinds

Central FL Remote

Sensing Lab

Dr. Linwood Jones

Univ. of Central FL

SEECS Box-162450

Orlando, FL 32816-

2450

US

[email protected]

Khalil

Ahmad

(NOAA

NESDIS)

Spencer

Farrar

(CFRSL)

Takis

Kasparis

(CFRSL)

Contributed

Poster

Meteorology The SeaWinds scatterometer

measures the ocean surface wind

vector; and it also measures the

polarized radiometric brightness

temperature of the ocean and

atmosphere, utilizing a ground

signal processing algorithm known

as the QuikSCAT Radiometer

(QRad). This paper describes an

oceanic rainfall retrieval algorithm

that combines the simultaneous

active (radar backscatter) and

passive (microwave brightness

temperatures) observations by the

SeaWinds sensor. The retrieval

algorithm is statistically based, and

has been developed using

collocated measurements from

SeaWinds, the Tropical Rainfall

Measuring Mission (TRMM)

Microwave Imager (TMI) rain

rates, and the National Center for

Environmental Prediction (NCEP)

surface wind fields. The rain is

retrieved on a wind vector cell

(WVC) measurement grid that has

a spatial resolution of 25 km. Due

to its broad swath coverage,

SeaWinds affords additional

independent sampling of the

oceanic rainfall, which may

contribute to the future NASA's

Precipitation Measurement

Mission (PMM) objectives of

improving the global sampling of

oceanic rain within 3-hour

windows. Examples of the

passive-only, as well as the

combined active/passive rain

estimates from SeaWinds are

presented. To evaluate the

accuracy of the retrievals,

comparisons are made with the

standard TRMM 2A12 rain data

remove



product and AMSR, SSMI and

AMSU microwave radiometer

rain retrievals. Results demonstrate

that QRad rain measurements are

in good agreement with the

independent microwave rain

observations. Also, since

SeaWinds is the only sensor

onboard QuikSCAT, the

SeaWinds rain estimates can be

used to improve the flagging of

rain-contaminated oceanic wind

vector retrievals by applying a

threshold on the retrieved rain

rates. In order to evaluate the

performance of the SeaWinds flag,

comparisons are made with the

Impact based Multidimensional

Histogram (IMUDH) rain flag

developed by JPL. Results

emphasize the powerful rain

detection capabilities of the

SeaWinds rain rate retrieval

algorithm.


Authors

Abstract


Validation of

QuikSCAT

Radiometer

Brightness

Temperatures

Central FL Remote

Sensing Lab

Dr. Linwood Jones

Univ. of Central FL

SEECS Box-162450

Orlando, FL 32816-

2450

US

[email protected]

Rafik

Hanna

(Central

FL

Remote

Sensing

Lab)

Contributed

Poster

Calibration/Validation

and definitions

The SeaWinds

scatterometer measures the

polarized radiometric

brightness temperature of

the ocean and atmosphere,

utilizing a ground signal-

processing algorithm known

as the QuikSCAT

Radiometer (QRad). QRad

brightness temperatures are

used to infer rain rate over

the oceans, which can be

used as a quality flag for

wind vector retrievals. This

poster paper presents

results of an inter-satellite

radiometric calibration that

was performed to assess

the quality of QRad

brightness temperature

measurements using near-

simultaneous ocean Tb

comparisons between the

remove



comparisons between the

SeaWinds on QuikSCAT

(QRad) and WindSat

polarimetric radiometer on

Coriolis. WindSat was

selected because it is well

calibrated radiometer that

has many suitable

collocations with

QuikSCAT; and it has a

10.7 GHz channel, which is

close to QRad frequency of

13.4 GHz. Translations

were made for WindSat

brightness temperatures

before comparison to

account for expected

differences in Tb with

QRad because of geometry

and channel frequency

differences. Brightness

temperatures for several

months during 2005 and

2006 were spatially

collocated for rain-free

homogeneous ocean scenes

(match-ups) within 1°

latitude x longitude boxes

and within a ± 60 minute

window. To insure high

quality comparison, these

collocations were quality

controlled and edited to

remove non-homogenous

ocean scenes and/or

transient environmental

conditions, including rain

contamination. So,

WindSat and QRad Tb’s

were averaged within 1°

boxes and these were used

for the radiometric inter-

calibration analysis on a

monthly basis. Results show

that QRad calibrations are

stable in the mean within ±

2K over the yearly seasonal

cycle.



TitleContact

Information

Other

Authors

Abstract


Determining

Tropical

Storm Eye

Location

from

QuikSCAT

Ultra High

Resolution

Wind

Fields

Brigham Young

University

Professor David

Long

459 Clyde

Building

Provo, UT

84602

USA

[email protected]

Faozi Said

(Brigham

Young

University)

Contributed

Poster


and definitions

The National Hurricane Center

(NHC) in Florida and the Joint

Typhoon Warning Center (JTWC)

in Hawaii provide best-track data

for named tropical cyclones. For a

given named tropical cyclone,

best-track data provides the most

probable eye location in latitude

and longitude at six hour intervals.

This information is gleaned from a

variety of sources, including near

real-time QuikSCAT 25 km

MGDR winds. Using

reconstruction resolution

enhancement techniques on

QuikSCAT sigma0 measurements,

2.5 km/pixel winds can be

derived. These ultra high resolution

(UHR) winds provide much more

detail about the location and

structure of tropical cyclones. In

this paper we validate tropical

cyclone centers derived from UHR

winds against best-track data. A

trained analyst locates center

locations of tropical cyclones in

both standard 25 km and UHR

QuikSCAT wind images over the

QuikSCAT mission. Comparison

is made between the analyst's

independent choice of eye location

and best-track's. The data are

divided into two categories based

on the analyst�s confidence level

in finding the eye center location.

One category contains UHR

images where the analyst has high

confidence in the storm's eye

location, whereas the other

category is the opposite. The latter

includes images where storms are

either under-developed or partially

shown. The error distance

between the analyst's choice of

eye center location and the

interpolated best-track position is

computed and the mean error

remove



distance, standard deviation and

the median are computed. Using

only QuikSCAT UHR data the

analyst obtain almost identical

results as best-track for high

confidence images, and very good

results for low confidence images.

A summary of the analysis of all

named storms over the

QuikSCAT mission is presented,

including the statistics on how

frequently named storms are

observed.

TitleContact

Information

Other

Authors

Abstract


Near-

Coastal

QuikSCAT

Wind

Products

Brigham Young

University

Professor David

Long

459 Clyde

Building

Provo, UT

84602

USA

[email protected]

Michael P.

Owen

(Brigham

Young

University)

Contributed

Poster

New

products

SeaWinds indirectly measures near surface

ocean winds from radar backscatter values

using a geophysical model function. Due to a

non-ideal antenna pattern, in near coastal

regions QuikSCAT wind retrieval accuracy is

limited due to land contamination of the

backscatter measurements. However, wind

retrieval in near coastal areas can be

successfully accomplished by estimating the

amount of land contamination in the

backscatter measurements and eliminating

those measurements which exceed a �land

contamination� threshold. The land

contamination threshold is a function of land

and ocean backscatter, which is a function of

the local wind speed and direction. The

method accounts for the observation

geometry, i.e. the orientation of the slices with

respect to the coast and the relative wind

direction. The threshold can be adjusted

during wind retrieval depending on wind speed

to allow retrieval closer to the coast as wind

speeds increase. In order to assess the land

contamination in a given backscatter

measurement, a detailed knowledge of each

slice spatial response function is employed.

Land contamination is quantified using the land

contribution ratio (LCR), which is calculated

using the spatial response and the estimated

nearby uncontaminated land and ocean

backscatter. The QuikSCAT spatial response

is pre-computed in a tabular form while the

wind speed-dependent LCR threshold is pre-

remove



determined using Monte Carlo simulation and

stored a look-up-table according to the local

wind speed, land backscatter, and the cross-

track swath location. The method supports

both conventional (25 and 12.5 km) and ultra

high resolution (2.5 km) wind retrieval. LCR-

based wind retrieval is more accurate closer to

the coast than previously achieved using both

low and high-resolution processing. The

precise distance varies with orbit and coast

geometry, and accurate winds can be retrieved

as close as 5 km from the coast in some cases.

Near-coastal buoy wind data is used to

validate the retrieved winds.


Authors

Abstract


An ENSO

Warm

Event

Precursor

Signal in

Sea Level

Pressure

and Surface

Winds on

the

Southern

Hemisphere

NWRA, CoRA

Division

Dr. Ralph Milliff

3380 Mitchell Lane

Boulder, CO 80301

USA

[email protected]

Harry van

Loon (lead

author)

(NWRA

CoRA and

NCAR)

Jan Morzel

(Rosetta

Consulting)

Contributed

Poster

Meteorology May-June-July (MJJ) averages of

anomaly maps of sea-level pressure

(SLP) in the South Pacific Ocean

depict an anomalous low in sub-

tropical and middle latitudes in most

of the years identified by El

Nino/Southern Oscillation (ENSO)

warm events (WE) that mature in the

tropics by the following December-

January-February (DJF). To identify

the precursor signal, we show MJJ

anomaly SLP maps averaged over 6

strong WE, and 10 weaker WE in the

Hadley Center global climatologies

since the 1950s. We also show MJJ

average SLP anomaly maps for 4

years when the signal was present,

but a WE did not ensue. MJJ average

anomaly surface vector winds (SVW)

can be computed from the

QuikSCAT record 2000 through

present. The weak WE years of 2002

and 2006 exhibit anomaly winds

consistent with the anomaly SLP

signal (also shown), leading to a

description of the pathways by which

anomaly signals lead to the warming

of equatorial upper ocean

temperatures in the central and

eastern Pacific, associated with

mature ENSO WE in those years.

remove




Authors

Abstract


Documenting

and

Enhancing

QuikSCAT

Utility for

NWS

Weather

Forecast

Office

Operations

NWRA, CoRA

Division

Dr. Ralph Milliff

3380 Mitchell Lane

Boulder, CO 80301

USA

[email protected]

Peter A.

Stamus

(NWRA

CoRA)

John S.

Snook

(NWP

Consulting)

Contributed

Poster

Other

science or

operations

Written (33) and site-visit (16)

surveys of the National Weather

Service, Weather Forecast Offices

(WFO) of the coastal United States

were conducted to document the utility

of surface vector wind data from

QuikSCAT in WFO operations.

Survey results demonstrate that: a)

QuikSCAT data supplement primary

datasets (e.g. IR imagery) and

numerical weather prediction fields in

the manual production of local weather

forecasts and warnings; b) operational

utility of QuikSCAT data would be

enhanced by surface vector wind

retrievals at finer temporal resolution,

closer to the coast; and c) rain flags in

the near-real time QuikSCAT dataset

have little impact on WFO operations.

In an attempt to address the

enhancement issues raised in the

surveys, QuikSCAT data were

ingested into the Local Area Prediction

System (LAPS) for test cases from the

Eureka, CA WFO (EKA). In at least

one test case, QuikSCAT-LAPS

raised winds in the EKA marine zone

to increase warning levels vs. LAPS

without QuikSCAT. Experiments are

currently in progress to examine

QuikSCAT impacts in local area

mesoscale models (MM5 and WRF)

for the EKA WFO using simple

nudging procedures for short-term

forecast runs.

remove


Authors

Abstract


Systematic

Geographic

Differences

between

ASCAT and

QuikSCAT:

Instrument,

Algorithm, or

Geophysical?

JPL/Cal Tech

Dr. Ernesto Rodrguez

MS 300-319 Jet Propulsion

Laboratory

4800 Oak Grove Dr.

Pasadena, CA, 91109

USA

[email protected]

Svetla

Veleva

(JPL)

Contributed

Poster


and definitions

The launch of

ASCAT on METOP

in 2006 brought a

second

scatterometer in

space, significantly

augmenting the

QuikSCAT

observations of the

remove



Geophysical? [email protected] observations of the

near-surface winds

over the global

oceans, thus allowing

for much improved

spatial and temporal

coverage. Before

combining the data

from the two sources

we need to

understand

similarities and

differences in the two

wind estimates. The

importance of this

issue is highlighted by

the need to have

consistency in wind

and stress estimates

from different

platforms for building

an extended climate

record and for using

ASCAT as the sole

surface wind to help

weather forecasting

and ocean modeling

in the near-term

post-QuikSCAT

era. In this study we

compare retrievals

from the two

missions in a

climatological and

geographical sense.

We focus on a seven

month period (from

10-16-2007 to 05-

27-2008) and

investigate the

temporal and spatial

structure of the wind

and the wind stress

as retrieved by

QuikSCAT and

ASCAT. We

compare and

contrast the two

estimates in terms of

mean latitudinal



mean latitudinal

values of the

retrieved zonal (U)

and meridional (V)

components and

their geographical

variability. We look

at the dynamical

significance of the

ASCAT/QuikSCAT

differences by

investigating how

they impact the high-

frequency and the

low-frequency

vorticity and

divergence fields,

and the coupling

between SST

gradients and near-

surface wind

response. In all cases

we evaluate the

retrievals in terms of

how they compare to

collocated ECMWF

analysis. This allows

us to lessen temporal

sampling differences

due to systematic

diurnal wind

variability. We find

that differences in the

U/V components

have consistent

geographic patterns,

some of which

coincide with Sea

Surface Temperature

fronts, while others

have local or basin

scale signatures. We

examine possible

sources for the

differences, including

issues relating to the

instrument, the model

functions, wind

retrievals and the

different physical



different physical

scattering

mechanisms at Ku

and C-band.

TitleContact

Information

Other

Authors

Abstract


Redevelopment

of a

Scatterometer

Model

Function Using

Nine Years of

QuikScat Data

Remote Sensing

Systems

Deborah Smith

438 First St

Suite 200

Santa Rosa, CA

95401

USA

[email protected]

Lucrezia

Ricciardulli

(Remote

Sensing

Systems)

Frank

Wentz

(Remote

Sensing

Systems)

Contributed

Poster

Other

science or

operations

Now that we have nearly a decade of

QuikScat observations, it seems prudent

to review the QuikScat geophysical

model function (GMF). The original

development of both the JPL and RSS

GMF were based on a limited amount of

data, particularly for winds above 15 m/s.

There are questions about the

dependence of the wind direction

harmonics on wind speeds above 15 m/s.

For example, does the amplitude of the

harmonics continue to increase with wind

speed or does the relationship flatten out?

Another concern is the effect of ocean

currents on the buoy versus QuikScat

intercomparisons used in the original

GMF derivations. And finally, given a

decade of data, some fine tuning of the

GMF is in order. The new GMF is based

on winds coming from buoys (primary

wind speed calibration for winds up to 15

m/s), NCEP (primary wind direction

calibration up to 25 m/s), and H*Wind

(wind speed and direction for very high

winds). Rather than having a separate

GMF at high winds, we are developing a

single GMF to cover all winds. The new

GMF is still under development, but we

will show some preliminary results in the

light of previous GMFs.

remove

TitleContact

Information

Other

Authors

Abstract


Validation

of ASCAT

Wind

Vectors

with Buoy,

Radiometer

and Model

Data

Remote Sensing

Systems

Deborah Smith

438 First St

Suite 200

Santa Rosa, CA

95401

USA

Kyle

Hilburn

(Remote

Sensing

Systems)

Frank

Wentz

(Remote

Sensing

Contributed

Poster


and definitions

BUFR ASCAT files obtained

from OSI SAF have been

downloaded and processed to orbit

files similar to the QuikScat files

available from Remote Sensing

Systems. The winds in the ASCAT

files are obtained using the

CMOD5.n model function at OSI

SAF. For this analysis, we use

remove



[email protected]) ASCAT data available after April

3, 2008 when the most recent beam

balancing and model function

changes were implemented. We will

present an analysis of wind speeds

and directions as compared to

ocean moored buoy winds, NCEP

GDAS winds, and QuikScat winds.

Also, there are currently multiple

radiometers available for

comparison with ASCAT wind

speeds. We provide statistics and

difference maps of ASCAT to

SSM/I, TMI and AMSR-E global

ocean winds.


Authors

Abstract


ASCAT

Normalized

Radar

Cross

Section

Validation

NOAA/NESDIS/STAR

Dr. Seubson Soisuvarn

5200 Auth Road

WWB room 102A

Camp Springs, MD 20746

USA

[email protected]

Zorana

Jelenak

(NOAA)

Paul

Chang

(NOAA)

Qi Zhu

(NOAA)

Contributed

Poster


and definitions

The Advanced

Scatterometer

(ASCAT) is a radar

instrument, flying on

board the MetOp-A

satellite, designed

specifically to retrieve

ocean surface wind

speed and direction.

The ASCAT transmits

5.255 GHz (C-band)

microwave energy, using

vertically polarized fan-

beam antennas, to the

ocean surface and

measures the returned

radar backscatter signal

(σ0) from small-scale

wind-driven sea surface

roughness. ASCAT

wind retrievals have

been validated against

NWS Global Data

Assimilation System

(GDAS) global wind

fields, QuikSCAT

satellite scatterometer

wind retrievals, and

oceanic buoy wind

measurements. The

result shows that

remove



ASCAT wind retrieval

performance is within 2

m/s RMS error for wind

speeds from 0-15 m/s

under all weather

conditions, and 20°

RMS directional error

for wind speeds > ~5

m/s. However, ASCAT

wind speed retrievals

are significantly

underestimated

compared to GDAS

and QuikSCAT winds

for wind speeds > ~15

m/s. To further

investigate the ASCAT

high wind speed

retrieval performance,

ASCAT σ0

measurements from

fore-, mid- and aft-

beams are compared

with predicted σ0

measurements to

determine measurement

residual errors and

possible adjustments in

the model function to

improve ASCAT

retrievals at higher wind

speeds. A wind vector

from a collocation

dataset of ASCAT with

the GDAS and

QuikSCAT are being

used with the CMOD5

to calculate the model

σ0. These σ0 are

compared with both of

ASCAT measured σ0

at 25- and 50-km

resolutions. The results

show that at wind

speeds > 15 m/s there

are σ0 measurement

residual errors across

the swath and that these

errors increase as a

function of wind speed.



function of wind speed.

An empirical relationship

between the measured

σ0 and “true” wind

vectors are established

and new model function

coefficients are

calculated. The

harmonic response

functions of wind speed

for the CMOD5 and the

empirical model function

are compared.


Authors

Abstract


Stress or

Wind:

Definitions

and

Biases

Florida State University /

COAPS

Professor Mark

Bourassa

Florida State University

200 R.M. Johnson

Building, 2035 E. Paul

Dirac Drive, PO Box

3062840

Tallahassee, FL 32306-

2840

USA

[email protected]

Barry

Vanhoff

(Oregon

State

University)

David E.

Weissman

(Hofstra

University)

Contributed

Talk


and definitions

Scatterometers have long

been considered to respond

to surface turbulent stress.

They have been calibrated

to wind-like quantities

(equivalent neutral winds)

due to the paucity of stress

observations. Equivalent

neutral winds are winds that

have been modified to be

more physically consistent

with stress. However, for

historical reasons, equivalent

neutral winds were made

consistent with friction

velocity, which is the square

root of the kinematic stress

(the stress divided by

atmospheric density). If

scatterometers do respond

to stress, this approach

introduces an error (a gain)

in wind speed related to the

square root of atmospheric

density. For scatterometer-

derived stress, the error

would be proportional to

density raised to the 1 to 1.5

power, depending on the

wind speed. This

dependency on air density is

examined, with the goal of

showing that scatterometer

backscatter is more closely

remove



backscatter is more closely

a function of surface stress

than wind speed or

equivalent neutral wind. The

influence of air density is a

gain, a proportional increase

or decrease, making the

impact far greater than a

random error. These

considerations could be

important in areas of strong

temperature gradients (e.g.,

the Gulf Stream, equatorial

cold tongues, and oceanic

fronts), cold air outbreaks,

and for large-scale

circulation studies. For large

gyre circulations, the

atmospheric density can

change by �b10% at the

equator-ward and pole-

ward extremes of the gyre,

relative to the average over

the gyre. Other relevant

applications are scalar

fluxes, such as sensible heat,

latent heat or moistures, and

some gas fluxes (e.g., CO2).

For scalar fluxes, the gain is

proportional to the

��proportional error in

density�� raised to the

0.5 to 0.75 power. These

errors are likely to be

physically important when

considering global budgets.

Collocated data from buoys

and the SeaWinds on

QuikSCAT scatterometer

are used to demonstrate that

scatterometer responses are

more stress-like than wind-

like.


Authors

Abstract


Error

Characteristics

of

Scatterometer-

Florida State University /

COAPS

Professor Mark

Contributed

Talk


and definitions

Our technique for

determining vorticity from

scatterometer

observations of surface

remove



Scatterometer-

Derived

Vorticity as a

Function of

Spatial Scale

Professor Mark

Bourassa

Florida State University

200 R.M. Johnson

Building, 2035 E. Paul

Dirac Drive, PO Box

3062840

Tallahassee, FL 32306-

2840

USA

[email protected]

observations of surface

vector winds is revised to

be much more versatile

and robust. Vorticity is

calculated using the

circulation, and the area

about which we are

calculating the circulation.

For calculations on the

smallest spatial scale, this

technique is

mathematically equivalent

to a finite difference.

Biases and random errors

are estimate as a function

of spatial scale. There are

three main sources of

error: random

observational error,

truncation errors related

to the assumption of linear

changes between wind

vectors, and errors

associated with mis-

matches in spatial scale.

The observational

component can be well

estimated, and is typically

small. The truncation

error is quite large,

particularly for small

spatial scales. Spatial

scales of greater than or

equal 75km (three grid

cells) greatly reduces the

noise; however, larger

spatial scales result in

biases. These results are

also discussed in the

context of desired

characteristics of future

satellites for measuring

ocean surface vector

winds with the goal of

examining tropical

cyclogenesis.

Title Contact Information Other AuthorsAbstract




Operational

Evaluation

and Use of

Satellite

Ocean

Surface

Vector

Wind Data

at the

National

Hurricane

Center and

Central

Pacific

Hurricane

Center

NOAA/NWS/NCEP

National Hurricane Center

Dr. Michael Brennan

11691 SW 17th Street

Miami, FL 33165-2149

USA

[email protected]

Richard D. Knabb

(NOAA/NWS

Central Pacific

Hurricane Center)

Hugh D. Cobb III

(NOAA/NWS/NCEP

National Hurricane

Center)

Paul S. Chang

(NOAA/NESDIS)

Zorana Jelenak

(NOAA/NESDIS)

Contributed

Talk

Meteorology The operational

utility of satellite

ocean surface

vector winds from

QuikSCAT and

ASCAT at the

National Hurricane

Center (NHC) and

Central Pacific

Hurricane Center

(CPHC) will be

presented. An

update on the

operational use of

QuikSCAT data

for tropical cyclone

center fixing,

intensity and

structural analysis

will be given, as

these data continue

to be heavily used

by NHC

forecasters,

particularly for

tropical cyclones

that are not

sampled by aircraft

reconnaissance.

The utility of

QuikSCAT data in

tropical and sub-

tropical marine

meteorological

applications will

also be

summarized. An

initial evaluation of

the operational use

of ASCAT data in

operational tropical

cyclone and marine

applications will

also be presented.

ASCAT’s

narrower data

swaths, coarser

resolution (and

therefore lesser

sensitivity to high

remove



sensitivity to high

wind speeds), and

reduced sensitivity

to rain make

ASCAT retrievals

quite different in

character from

those provided by

QuikSCAT. The

largest limitation of

ASCAT is that the

instrument provides

significantly fewer

passes over

tropical cyclones

and other weather

features of interest,

particularly at low

latitude. ASCAT

processing by

NOAA/NESDIS

and display

capabilities at

NHC have

continued to

evolve, improving

the utility of

ASCAT retrievals

when the data

swath does capture

the center of a

tropical cyclone.

Finally, comments

on plans for the

post-QuikSCAT

era from the

NHC/CPHC

perspective will be

provided.


Authors

Abstract


Characteristics

of High

Resolution

Winds from

Synthetic

Aperture

Radar

Measurements

CSTARS

Mr. Michael Caruso

11811 SW 168th St

Miami, FL 33177

USA

[email protected]

Contributed

Talk


and definitions

The Center for

Southeastern Tropical

Advanced Remote

Sensing (CSTARS) of

the University of Miami

(UM) has teamed with

the Canadian Space

Agency (CSA) and the

remove



Measurements Agency (CSA) and the

U.S. National Oceanic

and Atmospheric

Administration / Atlantic

Oceanographic and

Meteorological

Laboratory

(NOAA/AOML) in a

program to analyze C-

band Synthetic

Aperture Radar (SAR)

data acquired over

hurricanes. This

program was started in

1999 and has collected

over 300 images of

tropical cyclones. Wind

fields under hurricane

conditions are retrieved

from C-band SAR data

acquired by

RADARSAT-1.

RADARSAT-1 is a

right looking radar,

which acquires images

at C-band with

horizontal (HH)

polarization in transmit

and receive. Wind

speeds are computed

from the SAR

measured normalized

radar cross section

utilizing the

scatterometer CMOD5

model function. The

model function was

modified for the

Radarsat-1 HH

polarization using a C-

band polarization ratio.

To retrieve winds using

SAR, the wind direction

must be known a-priori

or estimated

reasonably. Wind

directions were

obtained using

numerical model winds

and linear features



and linear features

visible in the SAR

image associated with

wind streaks. High

resolution Synthetic

Aperture Radar (SAR)

winds fields over the

ocean show spatial

variability that have not

been modeled or

measured by any other

technique. This includes

the features produced

by topographic

influences in coastal

regions and by

hurricanes near the eye

wall or in the outer

bands. While the winds

derived from SAR

provide valuable

information about the

high resolution structure

of the wind field, the

winds also contain

systematic, random and

nonlinear errors. In this

analysis, the high

resolution two-

dimensional structure of

SAR derived wind

estimates of hurricanes

is compared with high

resolution scatterometer

and numerical model

winds. The SAR

derived wind fields

show unprecedented

details of the hurricane

eye, including location,

shape and size. These

comparisons

demonstrate the

potential usefulness of

the high resolution wind

fields such as those

from XOVWM.

Abstract





QuikSCAT

Follow-on

Efforts at

NOAA

NOAA/NESDIS/STAR

Dr. Paul Chang

NOAA Science Center

5200 Auth Road,

Room105

Camp Springs, MD

20746

USA

[email protected]

Zorana Jelenak

(NOAA/NESDIS/STAR-

UCAR)

Ernesto Rodriguez (Jet

Propulsion Laboratory)

Robert Gaston (Jet

Propulsion Laboratory)

Contributed

Talk

Plans for

post-

QSCAT

era

The operational use

of satellite ocean

surface vector wind

(OSVW) observations

has advanced

considerably over the

past decade. OSVW

data from research

(QuikSCAT and

WindSat) and

operational (ASCAT)

satellite systems are

now depended upon

and utilized daily by

operational weather

forecast and warning

centers around the

world. Availability of

QuikSCAT OSVW

revolutionized

operational marine

weather warnings,

analyses, and

forecasting within

NOAA’s National

Weather Service

(NWS) offices.

Therefore, to maintain

the significant

improvements in

operational weather

forecasting and warning

products realized today,

continuity of the

OSVW data stream at

a level that is equivalent

to or better than that

provided today by

QuikSCAT is required.

The next challenge for

global satellite OSVW

measurements in the

United States is to find

a way to make the

transition from a

research capability to a

sustained operational

capability. In June

remove



capability. In June

2007, following the

recommendation of the

National research

Council (NRC) decadal

survey, NOAA initiated

the QuikSCAT follow-

on study and funded

NASA’s Jet Propulsion

Laboratory (JPL) to

provide a cost,

technical risk, and

design analysis for three

possible mission options

(1) a QuikSCAT-

equivalent capability,

(2) an extended ocean

vector wind mission

(XOVWM) and (3)

XOVWM constellation

. To assess the

additional impacts that

the next-generation

scatterometer mission

(XOVWM) would

bring to NOAA

operations, and judge

whether those

improvements warrant

the differences in cost,

launch delay, and risk

between two instrument

options, a wide

NOAA/NWS user

impact study was

designed and

performed during winter

2007-08. To achieve

the study goals we

investigated the

differences in

performance between

the two OSVW mission

options in tropical

cyclones, extratropical

cyclones, and coastal

wind jet events using

JPL’s simulated wind

retrievals based on the

design of both the



design of both the

QuikSCAT-equivalent

instrument and

XOVWM.


Authors

Abstract


Observations

and

Modeling of

Coupled

Ocean-

Atmosphere

Interaction

Over the

California

Current

System

Oregon State University

Professor Dudley Chelton

104 COAS Administration

Building

College of Oceanic and

Atmospheric Sciences,


Corvallis, OR 97331-5503

USA

[email protected]

Xin Jin

(UCLA)

James C.

McWilliams

(UCLA)

and Tracy

Haack

(NRL

Monterey)

Contributed

Talk

Other A strong sea-surface

temperature (SST) influence

on surface winds and wind

stress is well established from

QuikSCAT observations of

winds and AMSR microwave

observations of SST over the

SST fronts associated with the

eastward extensions of

westward boundary currents

into the interior ocean. In

combination with higher-

resolution satellite infrared-

based SST analyses,

QuikSCAT wind observations

reveal that this ocean-

atmosphere interaction also

occurs over eastern boundary

currents where the scales of

SST fronts are much smaller.

In particular, the SST

influence on the wind stress

curl that drives open-ocean

upwelling results in order-1

perturbations of the large-

scale background wind stress

curl field. On the atmosphere

side, the SST influence on

surface winds can be

reproduced quite accurately

with mesoscale models with a

sufficiently accurate and high-

resolution SST boundary

condition and appropriate

parameterization of vertical

turbulent mixing. In particular,

it will be shown that the SST-

induced perturbations of the

surface wind field are well

represented over the

California Current System by

the U.S. Navy Coupled

Ocean-Atmosphere

remove



Ocean-Atmosphere

Mesoscale Prediction System

(COAMPS) model run in a 1-

way coupled configuration in

which SST forces the

atmosphere. The feedback

effects of the SST-induced

perturbations of the wind

stress and wind stress curl

fields on the ocean are only

beginning to be explored. It

will be shown from a simple

empirically based coupled

model of an idealized eastern

boundary current system that

the feedback significantly

alters the shallow equatorward

surface flow and the nearshore

deep poleward counterflow.

These equatorward and

poleward flows are analogous

to the California Current and

the California

Undercurrent/Davidson

Current. The coupling also

modifies the mesoscale eddy

field, preferentially weakening

the cyclonic eddies because of

their stronger SST signatures

compared with anticyclonic

eddies.


Authors

Abstract


Evaluation

of

ASCAT

wind

vectors

Hokkaido University

Professor Naoto Ebuchi

Institute of Low Temperature

Science, Hokkaido University

N19-W8, Kita-ku

Sapporo 0600819, Japan

Japan

[email protected]

Contributed

Talk


and definitions

Vector winds

observed by ASCAT on

Metop-A are evaluated

by comparing with buoy

data and assessing the

self-consistency of

statistical distributions of

wind speed and

direction. The bias and

root-mean-squared

differences between the

ASCAT wind speed and

direction and buoy

observations are -0.19

m/s and 1.5 deg., and

0.86 m/s and 18.6 deg.,

remove



0.86 m/s and 18.6 deg.,

respectively. Though the

ASCAT wind speed is

slightly higher (0.2 m/s)

than buoys data, the rms

differences are

comparable to or slightly

better than those for the

comparison of SeaWinds

data with buoy

observations. Analysis of

the wind speed residual

indicated that the

ASCAT wind speed is

systematically

underestimated at wind

speed higher than 15 m/s.

Comparison with

ECMWF wind speeds

also showed a similar

result. Histograms of

wind directions relative to

the satellite flight direction

exhibited systematic

directionality of ASCAT

wind vectors relative to

the antenna beams at

low- to mid- wind speed

ranges. These results

suggest that further

improvements of the C-

band geophysical model

function are needed.


Authors

Abstract


Overview

and

status of

ASCAT

products

and

services

EUMETSAT

Ms. Julia Figa-Saldana

Am Kavalleriesand 31

64295 Darmstadt

Germany

[email protected]

H. Bonekamp

(EUMETSAT)

C. Ponsard

(EUMETSAT)

C. Anderson

(EUMETSAT)

J. Wilson

(EUMETSAT)

A. de Smet

(EUMETSAT)

C. Duff

(EUMETSAT)

L. Butenko

(EUMETSAT)

Contributed

Talk

Other

science or

operations

The Advanced Scatterometer

(ASCAT) on METOP-A is a real

aperture, vertical polarisation, C band

radar. It has been designed with the

primary objective of providing near

surface winds over the global oceans

in all weather conditions. Other

important parameters can be

estimated and monitored from

ASCAT data, such as sea ice

coverage, concentration and type and

soil moisture over land.

EUMETSAT�s primary objective is

to provide users with satellite data

remove



(EUMETSAT) to provide users with satellite data

products for operational applications.

In that context, the EUMETSAT

Polar System (EPS) provides a range

of ASCAT products, with emphasis

on near real time services with a high

degree of reliability and continuity.

Global backscatter coefficient values

are provided in near real time, at

approximately 50 and 34 km

resolution, on a 25 km and 12.5 km

swath grid spacing, respectively. The

EUMETSAT Ocean and Sea Ice and

Numerical Weather Prediction

Satellite Application Facilities (OSI

and NWP SAFs) further extend these

services to Level 2 ocean winds and

various scatterometer processing

software modules. EUMETSAT also

provides in near real time global

ASCAT Level 2 soil moisture

products. Additionally, the

EUMETSAT Advanced

Retransmission System (EARS)

provides fast access to ASCAT Level

2 winds on regional coverage, aiming

at products dissemination after only

30 minutes from sensing. The EARS

products are intended to satisfy the

need for surface winds of regional

weather forecasting and nowcasting

applications. A description and

summary of the status of all the

ASCAT services above is given,

together with access details and links

to supporting user documentation.


Authors

Abstract


Incorporation

of New

Nonlinear

Similarity

PBL Model

in Ocean

Vector Wind

Surface

Pressure

retrievals

APL, University of

Washington

Ralph Foster

1013 NE 40th St.

Seattle, WA, 98105-

6698

USA

[email protected]

Jerome

Patoux

(Atmospheric

Sciences

UNiversity of

Washington)

R. A. Brown

(Atmospheric

Sciences

UNiversity of

Washington)

Contributed

Talk

Meteorology Our existing techniques for

surface pressure retrievals

from satellite ocean vector

wind data have proved useful

for both storm research and

operational forecasting. The

method is based on a linear

similarity PBL model that

excludes the effects of

nonlinear mean flow advection

when estimating the pressure

remove



Washington) when estimating the pressure

gradients that are associated

with observed surface wind

vectors. At present we make

a partial correction for these

neglected contributions

through an iterative "gradient

wind" correction. An

alternative methodology is to

incorporate the advective

terms into the similarity PBL

model, which removes the

need for an ad hoc gradient

wind correction. We present

our first experiments with

pressure retrievals using the

new PBL model.


Authors

Abstract


IWRAP -

Observations

from

Hurricane

Ike and

Status of

Data

Products and

Availability

University of

Massachusetts

Professor Stephen

Frasier

Microwave Remote

Sensing Laboratory

151 Holdsworth Way,

Rm 113A

Amherst, MA 01003

USA

[email protected]

Tao Chu (U.

Massachusetts)

Joe McManus

(U.

Massachusetts)

Robb

Contreras (U.

Massachusetts)

Paul Chang

(NOAA

NESDIS)

Zorana Jelenak

(NOAA

NESDIS)

Dragana

Perkovic (JPL)

Daniel

Esteban-

Fernandez

(JPL)

Contributed

Talk


and definitions

Dual-frequency (C-

and Ku-band) ocean

NRCS and volume

reflectivity observations

obtained by the

Imaging Wind and Rain

Airborne Profiler

(IWRAP) in Hurricane

Ike are presented.

Improved sensitivity for

penetrating heavy

precipitation has been

implemented via pulse

compression at both

frequencies, and a real-

time signal processor

has enabled more rapid

production of data

products. For this

season, Ku-band (VV)

and C-band (HH)

were collected to

augment existing high-

wind and low-wind

observations both with

and without

precipitation. When

possible flights were

also coordinated with

overpasses of ASCAT

remove



overpasses of ASCAT

and QuikSCAT. A

web-accessible data

repository has been

created for the

OVWST community to

access IWRAP data.

Data products

available include

reflectivity, NRCS, and

Doppler observations

in the instruments

native conical-scan

geometry, as well as

these products binned

by along-track location

and azimuth angle.

Companion aircraft

navigation data, flight-

level winds, and

surface wind and rain-

rate from the Stepped

Frequency Microwave

Radiometer (SFMR)

are also incorporated

with these data. An

overview of available

data sets and their

access are described.


Authors

Abstract


From El

Niño to

Atlantic

Niño:

pathways

as seen in

the

QuikScat

winds

Jackson School of

Geosciences, The

University of Texas at

Austin

Professor Rong Fu

Department of

Geological Sciences

1 University Station

C1100

Austin, TX 78712-

0254

USA

[email protected]

(Jackson

School of

Geosciences)

Contributed

Talk

Meteorology Although the influence of El Niño

on Atlantic Niños has been shown

empirically, the physical pathways

behind such empirical correlation are

still unclear, especially that links the

timing of El Niño influence to the

onset of Atlantic Niños. In this

presentation, we will show how El

Niño induced circulation change

work with seasonal migration of the

rainfall center over the South

America to influence surface winds

and ocean mixing layer over the

tropical Atlantic, and thus Atlantic

Niño using QuikScat winds, DT-

MSLA merged altimeter sea-level

high anomalies, TRMM and

PIRATA buoys.

remove



PIRATA buoys.


Authors

Abstract


From El

Niño to

Atlantic

Niño:

pathways

as seen in

the

QuikScat

winds

Jackson School of

Geosciences, The

University of Texas at

Austin

Professor Rong Fu

Department of

Geological Sciences

1 University Station

C1100

Austin, TX 78712-

0254

USA

[email protected]

(Jackson

School of

Geosciences)

Contributed

Talk

Meteorology Although the influence of El Niño

on Atlantic Niños has been shown

empirically, the physical pathways

behind such empirical correlation are

still unclear, especially that links the

timing of El Niño influence to the

onset of Atlantic Niños. In this

presentation, we will show how El

Niño induced circulation change

work with seasonal migration of the

rainfall center over the South

America to influence surface winds

and ocean mixing layer over the

tropical Atlantic, and thus Atlantic

Niño using QuikScat winds, DT-

MSLA merged altimeter sea-level

high anomalies, TRMM and

PIRATA buoys.

remove


Authors

Abstract


Intraseasonal

latent heat

flux based

on satellite

observations

University of Maryland

Dr. Semyon Grodsky

Computer and Space

Sci. Bldg., #2409

Department of

Atmospheric and

Oceanic Science

College Park, MD

20742

USA

[email protected]

Abderrahim

Bentamy

(IFREMER)

James A.

Carton

(UMD)

Rachel

Pinker

(UMD)

Contributed

Talk

Oceanography Weekly average satellite

based estimates of latent heat

flux (LHTFL) are used to

characterize spatial patterns and

temporal variability in the

intraseasonal band (periods

shorter than 3 months). The

strongest intraseasonal LHTFL is

observed at middle latitudes in

the regions of major SST fronts

where the standard deviation of

intraseasonal LHTFL is up to 50

Wm-2. Amplitude of

intraseasonal LHTFL decreases

at high latitudes and in the

regions of equatorial upwelling

reflecting the effect of decreased

SST. In middle latitudes the

intraseasonal variability of

LHTFL is forced by passing

storms and is locally amplified by

unstable air stratification over

warm SSTs. Although weaker in

amplitude but still significant

remove



intraseasonal variability is

observed in the tropical Indian

and Pacific Oceans due to the

eastward propagation of

Madden-Julian Oscillations. In

this tropical region the

intraseasonal LHTFL and

incoming solar radiation vary

out-of-phase, i.e. evaporation

enhances just below convective

clusters. Over much of the global

Ocean anomalous LHTFL

provides a negative feedback on

the underlying intraseasonal SST

anomaly, although there are

considerable geographical

variations. The feedback

exceeds 20 Wm-2/oC in the

regions around 20oS and 20oN,

but decreases at high latitudes

and in the eastern tropical Pacific

and Atlantic where the time

average LHTFL is weak.


Authors

Abstract


Evaluating

ocean

wind

products

for short-

range

forecast

analyses

of wind-

driven

surface

currents

Earth & Space

Research

Mr. John Gunn

Seattle, WA

USA

[email protected]

Kathleen

Dohan

(Earth &

Space

Research)

Gary S.E.

Lagerloef

(Earth &

Space

Research)

Fabrice

Bonjean

(Earth &

Space

Research)

Contributed

Talk

Other The main goal of our Ocean Vector

Wind project is to assess and implement

a methodology for the real-time estimate

and short-range prediction of high-

resolution ocean mixed-layer currents on

a 1-to-5 day basis. Earlier studies have

shown that eddy-viscosity

parameterizations of satellite-derived

wind-driven ageostrophic velocity

significantly contribute to the skill at

reproducing real currents. Atmospheric

forecast products will be used to calculate

the forecast wind-driven components.

The present study evaluates the accuracy

of the NCEP and ECMWF atmospheric

GCM re-analyses at measuring ocean

surface winds, through systematic

comparison with mooring wind data. An

Intercomparison between the atmospheric

re-analyses and the QuikScat gridded

fields are also carried out in order to

assess the spatial and temporal structure

differences in the products and the

remove



products transition from delayed-time

(QuikScat and later A-SCAT) to real-

time and forward (GCMs). Ultimately the

wind-driven current analysis and method

will be applied to the NOAA Ocean

Surface Current Analyses Real-time

system (OSCAR,

http://www.oscar.noaa.gov ) in order to

extend its capability to nowcast and

short-range forecast. On-going

developments of OSCAR are presented.

In particular a new high-resolution

OSCAR product will be released soon

and a QuikScat gridded field (1/3 degree)

evaluated as it is integrated into the

OSCAR system.


Authors

Abstract


Indian

Ocean

Intraseasonal

Sea Surface

Temperature

Variability

During

Boreal

Summer:

Madden-

Julian

Oscillation

Versus

Submonthly

Forcing and

Processes

University of Colorado at

Boulder

Dr. Weiqing Han

Dept. of Atmospheric and

Oceanic Sciences,

University of Colorado

UCB 311

Boulder, Co 80309

USA

[email protected]

Benet

Duncan

(NA)

Contributed

Talk

Oceanography Intraseasonal sea-surface

temperature (SST) variability in

the Indian Ocean during boreal

summer is investigated with a

series of experiments using the

HYbrid Coordinate Ocean

Model (HYCOM).

QuickSCAT winds and satellite

observed outgoing longwave

radiation (OLR) are used to

identify the wind and convection

patterns associated with

atmospheric intraseasonal

oscillations (ISOs). Effects of

the Madden-Julian Oscillation

(MJO; 30-90 days) and

submonthly ISOs are separately

examined. Similar to winter,

MJO forcing dominates

summertime SST variability,

even though submonthly forcing

is stronger. Wind plays a much

larger role in altering SSTs than

either shortwave fluxes or

precipitation. Different from

winter cases studied by Han et

al. (2007), the maximum

summertime SST variability

shifts to the Arabian Sea (AS)

and the Bay of Bengal (BOB),

when ISOs also shift to the

remove



when ISOs also shift to the

northern hemisphere. In the

BOB, surface heat fluxes due to

changes in wind speed have a

stronger influence on SST than

upwelling and advection induced

by wind stress, whereas in

winter the effects of wind speed

and stress are comparable. This

difference arises from the barrier

layer and thin surface mixed

layer in the BOB, which reduces

the effects of upwelling and

amplifies the effects of surface

heat fluxes. In the AS, surface

heat fluxes and entrainment

cooling caused by wind speed

have a larger effect on MJO-

scale SST than wind stress,

while the two have comparable

effects on submonthly SST. In

the equatorial region wind speed

and stress are equally important.


Authors

Abstract


The usage of

Scatterometer

data at

ECMWF

ECMWF

Dr. Hans Hersbach

ECMWF

Shinfield Park

RG2 9AX

United Kingdom

[email protected]

Dr.

P.E.A.M.

Janssen

(ECMWF)

Contributed

Talk

Other

science or

operations

At the European Centre for

Medium-Range Weather

Forecasts (ECMWF)

scatterometer winds have been

assimilated in the operational

integrated forecast and assimilation

system from 30 January 1996

onwards. The four-dimensional

variational assimilation system at

ECMWF allows for a dynamically

consistent use of observations. In

this way, information of

scatterometer surface winds is

propagated to the entire

troposphere. Currently, data is

used from the AMI scatterometer

on-board the European Remote

sensing Satellites ERS-2 (from

June 1996 onwards), the

SeaWinds instrument on-board

QuikSCAT (from January 2002

onwards), and from the ASCAT

instrument on the MetOp-A

platform (from June 2007

remove



platform (from June 2007

onwards). Thanks to the different

timing of ascending nodes of these

three satellites, most areas on the

globe are covered within a six-

hour period. Morning and

afternoon are captured by

QuikSCAT, while noon and

midnight are served by ASCAT

and ERS-2. Besides active

assimilation, the characteristics of

scatterometer data are routinely

monitored and inter compared. An

example of cross validation will be

given. A recent change in the

usage of QuikSCAT data, and the

recent construction of a C-band

geophysical model function for

equivalent neutral wind (called

CMOD5.N), will be presented.

Some preliminary results of

ongoing research regarding the

inclusion of the effects of ocean

currents and atmospheric stability

on the assimilation of

scatterometer data will be

discussed.



Near

Real-

Time

ASCAT

Wind

Vectors

at

NOAA

NOAA/NESDIS/STAR-

UCAR

Dr. Zorana Jelenak

NOAA Science Center

5200 Auth Road,

Room102

Camp Springs, MD

20746

USA

[email protected]

Paul Chang

(NOAA/NESDIS/STAR)

Seubson Soisuvarn

(NOAA/NESDIS/STAR)

Qi Zhu

(NOAA/NESDIS/STAR)

Jeffrey Augenbaum

(NOAA/NESDIS/OSDPD)

Gene Legg

(NOAA/NESDIS/OSDPD)

Stephen Frasier (University

of Massachusetts)

Tao Chu (University of

Massachusetts)

Contributed

Talk

New

products

NOAA and

EUMETSAT have a

partnership to

cooperate in providing

meteorological data

from their polar-

orbiting satellites.

NOAA and

EUMETSAT collect

and exchange

environmental data and

distribute it to users.

EUMETSAT operates

the METOP satellite

series, while NOAA

operates its Polar-

orbiting Operational

Environmental Satellites

(POES) which will be

succeeded by the

remove



succeeded by the

National Polar-orbiting

Operational

Environmental Satellite

System (NPOESS).

Working

collaboratively with

EUMETSAT and

KNMI, NOAA has

established the

infrastructure to

acquire, process, and

distribute ASCAT

products from the

EUMETSAT METOP

satellites. NOAA

commenced NRT

ASCAT processing in

a pre-operational mode

in February 2007.

Today ASCAT wind

products with two

different spatial

samplings, 25 and

12.5km, are produced

and distributed in near

real-time (NRT) to

NOAA’s operational

users. An overview of

the NOAA/NESDIS

NRT processing and

distribution of ASCAT

wind products will be

presented here. NOAA

is also participating in

ASCAT cal/val

campaigns. In support

of the ASCAT cal/val,

statistical comparisons

with QuikSCAT wind

vector retrievals, the

winds from the NWS

Global Data

Assimilation System

(GDAS), and with data

from deep ocean buoys

has been performed.

These analyses include

wind retrieval

performance



performance

comparisons in rain and

non-rain conditions and

as a function of various

satellite parameters

such as swath position.

NOAA is also

conducting field

experiments as part of

its ASCAT cal/val

effort. This field

campaign is in

cooperation with

EUMETSAT and

KNMI colleagues. The

Imaging Wind and Rain

Airborne Profiler

(IWRAP), an

advanced C-band and

Ku-band profiling radar

system developed and

built by the University

of Massachusetts, is

one of the core

instruments installed on

the NOAA P-3 aircraft

for this experiment.

Other instrumentation

includes GPS

dropsondes, which will

provide wind and

temperature profiles

through the

atmosphere, AXBTs

for sea surface

temperatures, the

Stepped Frequency

Microwave Radiometer

for surface wind speed

and rain rate estimates.



Improved

OVW

Retrievals

in

Extreme

Wind

Events

Central FL Remote

Sensing Lab

Dr. Linwood Jones

Univ. of Central FL

SEECS Box-162450

Orlando, FL 32816-

Pete

Laupattarakasem

(CFRSL)

Christopher C.

Hennon (Univ.

North Carolina -

Asheville)

Contributed

Talk

New

products

Due to the high surface winds

and associated heavy precipitation,

extreme wind events, such as

tropical cyclones, present a

daunting challenge to space-borne

Ku-band scatterometer

measurements of ocean vector

remove



Events Orlando, FL 32816-

2450

US

[email protected]

Asheville) measurements of ocean vector

winds. High rain rates attenuate the

ocean surface backscatter due to

surface winds and rain volume

scattering increases the sigma-0

measured by the scatterometer.

Thus, rain can either increase or

decrease the observed

backscattered power compared to

ocean measurements without rain;

and for both of these conditions,

wind retrievals that ignore rain are

significantly degraded. This paper

describes recent developments of

an improved ocean wind vector

retrieval algorithm that uses both

active and passive measurements

from QuikSCAT to infer

simultaneous wind vector and rain

rate measurements. Ocean

brightness temperature,

determined passively, is used to

model both the transmission and

scattering effects of rain, which are

used to correct the measured

sigma-0 at 12.5 km resolution.

Wind retrievals are performed

using an improved geophysical

model function (GMF) tuned with

high speed surface wind

measurements derived from

NOAA hurricane hunter aircraft

underflights. This algorithm results

in significant improvements in wind

vector measurements in hurricanes

and other extreme wind events and

better rain-flagging of severely rain

contaminated areas than does

NASA�s standard wind vector

product (L2B). The results from

this algorithm, known as Q-Winds,

are compared to an independent

surface wind analysis derived from

near-simultaneous NOAA aircraft

flights through several hurricanes

with multiple satellite passes.

Airborne sensors, that include the

Stepped Frequency Microwave

Radiometer, GPS

dropwindsondes and flight-level



dropwindsondes and flight-level

inertial navigation winds, are used

by the NOAA Hurricane Research

Division�s H*Wind Analysis

System to derive a reliable surface

wind field. Comparisons are

presented for H*Wind, Q-Winds

and the SeaWinds Projects new

L2B12.5 ocean vector winds

products.


Authors

Abstract


Wind stress

measurements

from the

QuikSCAT-

ADEOSS-II

tandem

mission and

the impact on

an ocean

model

Jet Propulsion

Laboratory

Dr. Tong Lee

4800 Oak Grove Drive

Pasadena

CA 91109

USA

[email protected]

Ou Wang

(Jet

Propulsion

Laboratory)

Wenqing

Tang (Jet

Propulsion

Laboratory)

W. Timothy

Liu (Jet

Propulsion

Laboratory)

Contributed

Talk

Oceanography We examine diurnal signals

captured by the SeaWinds

scatterometers during the

QuikSCAT-ADOESS-II

tandem mission during April-

October 2003) and their impact

on ocean model simulation. The

diurnal variability captured by

twice-daily scatterometer wind

from the tandem mission is

substantially larger than that

estimated by the NCEP

reanalysis product (even with a

6-hourly interval in the latter).

Consequently, the impact of

diurnal wind on model SST is

significantly larger with

scatterometer than with NCEP

winds because of stronger

vertical mixing caused by the

twice-daily scatterometer wind.

This is consistent with previous

studies that high-frequency

wind at the ocean�s inertial

frequencies enhances vertical

mixing through resonant inertial

oscillations. The weak vertical

mixing associated with daily

scatterometer winds causes

warm bias of SST (relative to

that resulting from twice-daily

scatterometer wind) and larger

deviation from observations.

The warm bias reaches several

�C in mid-latitude oceans

during summertime and can

accumulate with time. Heat flux

remove



accumulate with time. Heat flux

correction methods that attempt

to account for the feedback of

SST would propagate the error

in wind and vertical mixing to

the heat flux without correcting

the source of the error.

Because of this incorrect error

compensation, caution is

needed in the interpretation of

SST budget resulting from

ocean models and data

assimilation outputs based on

wind products that do not

adequately resolve diurnal

variability. Our findings highlight

the need to resolve diurnal wind

in future scatterometer missions.


Authors

Abstract


Oceanic

Origin of

Precipitation

Jump in the

Sahel

Jet Propulsion Laboratory

Dr. W Timothy Liu

MS 300-323, 4800 Oak

Grove Dr.

Pasadena, CA 91109

USA

[email protected]

Xiaosu Xie

(Jet

Propulsion

Laboratory)

Kristina

Katsaros

(Jet

Propulsion

Laboratory)

Contributed

Talk

Other

science or

operations

Observation from the

Tropical Rain Measuring

Mission confirms a rather abrupt

transition of rainfall at 8°N

latitude in the western Africa

between the Sahara and the

Gulf of Guinea. North of this

latitude, rainfall peaks in August,

and south of it, rainfall peaks in

June. There were postulations

on this precipitation jump

through data analysis and

numerical model, but no

satisfactory explanation of the

phase shift of the annual cycle is

evident. Using the moisture

transport integrated over the

depth of the atmosphere (IMT)

over ocean derived from

QuikSCAT data, we show that

the IMT comes onshore from

the Atlantic only around August

and lags those coming from the

Gulf of Guinea (GG), which

peaks in June, by two months.

The implication is that, the

onshore moisture transport by

the monsoon is confined to the

surface with off shore transport

remove



surface with off shore transport

aloft for most of the summer,

except for a summer months.

During the August, the on shore

transport extends far up in the

troposphere supplying moisture

and instability for heaviest

rainfall in the Sahel. The

anomalous wet season in 1999

is caused by the positive

(eastward) anomalies of IMT

from the Atlantic and the

anomalous dry summer of 2005

is associated with negative

(westward) anomalies of IMT

over the Atlantic. The

socioeconomic vulnerability of

the agricultural societies in the

Sahel region of West Africa to

the vagary of summer rainfall

has received world

recognizance. The recently

initiated international endeavor

of the African Monsoon

Multidicispline Analysis

underscores the fundamental

gaps in our knowledge of the

coupled atmosphere-ocean-land

system in this region and the

large systematic errors in

dynamical models used for

prediction. The results of this

study should made timely

fundamental advances in our

understanding the factors

controlling rainfall in the west

Africa.


Authors

Abstract


Surface

Wind/Stress

Structure

under

Hurricanes


Dr. W Timothy Liu

MS 300-323, 4800 Oak

Grove Dr.

Pasadena, CA 91109

USA

[email protected]

Wenqing

Tang (Jet

Propulsion

Laboratory)

Contributed

Talk

Other Surface Wind/Stress

Structure under Hurricanes

Wenqing Tang and W. Timothy

Liu Over eight years of

QuikSCAT scatterometer data

are used to study the wind-

stress relation and the

asymmetric pattern of the ocean

surface wind/stress fields under

hurricanes. QuikSCAT

remove



hurricanes. QuikSCAT

measurements collocated with

hurricanes are selected by

matching with available

operational best track

information globally. The

azimuthal distribution relative to

storm motion of the equivalent

neutral wind vectors,

backscatter, and precipitation

within 500 km distance from

hurricane centers are examined

and compared with available

operational wind products (e.g.

HWind from NOAA’s

Hurricane Research Division in

North Atlantic Ocean). Global

data are also separated

according to ocean basins and

hurricane intensity. The changes

of wind-stress asymmetry with

translation speed and ocean

basin are examined. Despite rain

contamination and the saturation

of backscatter under high wind,

we could still demonstrate the

impact of scatterometer

observations in understanding

organization of convections, air-

sea momentum-energy

exchange, and evolution and

intensification of a hurricane.

TitleContact

Information

Other

Authors

Abstract


Progress

in Ultra

High

Resolution

Wind and

Rain

Estimation

Brigham Young

University

Professor David

Long

459 Clyde

Building

Provo, UT

84602

USA

[email protected]

Contributed

Talk

New

products

Originally designed only for low resolution

wind retrieval, it has been demonstrated that

QuikSCAT observations can be used to

simultaneously estimate wind and rain at 25 km

resolution with reasonable accuracy. Coupled

with sigma-0 reconstruction techniques,

simultaneous wind/rain (SWR) estimation can also

be applied at an ultra-high resolution (UHR) of

2.5 km. The higher resolution minimizes beam-

filling effects and is more commensurate with the

small size of rain cells, but the oblique geometry,

inexact reconstruction, high noise level, and

computational requirements introduces

complications in UHR SWR retrieval.

Nevertheless, UHR SWR is surprisingly effective

remove



Nevertheless, UHR SWR is surprisingly effective

in detecting and mapping rain and improving wind

accuracy in the presence of rain. UHR SWR rain

estimates compare well with collocated TRMM-

PR rain values and provide an effective rain flag.

UHR SWR winds are improved over UHR wind-

only retrieval in regions of rain. In this

presentation, key tradeoffs and analysis results

are discussed, including model-based techniques.

The latter includes Bayesian models designed and

optimized for hurricane observation. A modified

wind/rain model function for use at UHR is

derived from collocated TRMM-PR, NCEP, and

QuikSCAT. A prototype UHR wind and rain

product that includes land contamination rejection

is described. Validation of UHR SWR winds and

rain is also discussed. A fundamental difficulty in

validating UHR wind and rain is the lack of

suitable comparison data. However, a fortuitous

occurrence of nearly simultaneous QuikSCAT

and Radarsat-1 ScanSAR passes over Hurricane

Katrina provides a unique opportunity for

validation. Using collocated H*winds and

NEXRAD rain observations, 1 km resolution

wind speed fields are derived from the Radarsat

sigma-0 images. Clearly observed high resolution

rain effects are described and the implications of

these observations on simultaneous wind/rain

retrieval are discussed.


Authors

Abstract


Quantifying

QuikSCAT

Value-Added

in Estimates of

the Surface

Wind Field

over the

Mediterranean

Sea on Ocean

Forecast

Timescales

NWRA, CoRA

Division

Dr. Ralph Milliff

3380 Mitchell Lane

Boulder, CO 80301

USA

[email protected]

Nadia

Pinardi

(INGV

Bologna)

Alessandro

Bonazzi

(INGV

Bologna)

Christopher

K. Wikle

(U.

Missouri)

Jeremiah

Brown

(Florida

State Univ)

Contributed

Talk

International

Collaboration

Sensitivity tests in a Bayesian

Hierarchical Model (BHM) to

estimate the surface vector wind

(SVW) process over the

Mediterranean Sea are used to

quantify the value of scatterometer

observations for basin-scale

ocean forecasts. Sensitivity

experiments focus on the relative

impacts of SVW data stage inputs

from QuikSCAT data and

ECMWF analyses and forecasts,

as well as sea-level pressure

inputs from ECMWF. Value

added is quantified in terms of

uncertainty measures of posterior

distributions for SVW fields on a

0.5 deg grid, over a 14-day

remove



0.5 deg grid, over a 14-day

(sequential) analysis period,

followed by a 10-day forecast

period. Posterior distributions for

BHM parameters and summary

fields (i.e. wind-stress curl) are

also examined as functions of the

data stage inputs. The approach is

designed to provide statements of

the form: ``SVW observations

from QuikSCAT reduce the

average uncertainty in SVW

estimates on 6-hourly timescales

by X%, over a 14d analysis

period, and they reduce the

uncertainty in SVW forecast

estimates by Y% over a

subsequent 10d forecast period

for which no QuikSCAT data are

available."


Authors

Abstract


Wind-driven

transport of

the

Apalachicola

River plume

as a

connectivity

mechanism

between

terrestrial

precipitation

variability

and offshore

oceanic

properties

The Florida State

University

Dr. Steve Morey

Center for Ocean -

Atmospheric

Prediction Studies

The Florida State

University

Tallahassee, FL

32306-2840

USA

[email protected]

Mark

Bourassa

(The Florida

State

University)

Dmitry

Dukhovskoy

(The Florida

State

University)

Contributed

Talk

Oceanography Satellite ocean color derived

estimates of monthly chlorophyll a

concentration over the northern

West Florida Shelf show high

interannual variability

concentrated near the coastline

and extending at least 150 km

offshore in a tongue-like pattern

from the Apalachicola River

during the late winter through

early spring. These anomalies are

consistent with interannual

variability in the flow rate of the

Apalachicola River, which is a

dominant nitrogen source to the

region. A series of numerical

model experiments are conducted

to explain the physical mechanism

responsible for connecting the

variability within the river plume,

which is traditionally thought to

follow the coastline, with the

offshore environment. Results

show no connectivity under

climatology surface wind forcing.

However, experiments forced by

wind fields derived from satellite

remove



wind fields derived from satellite

scatterometer data capturing

synoptic scale weather features

show intermittent episodes of

offshore transport of the

Apalachicola River plume across

the shelf under upwelling-

favorable winds. A series of these

offshore-directed plumes during

the winter – spring season alters

the monthly averaged

hydrographic and biochemical

properties offshore, with the

oceanic anomalies varying with

anomalous wet and dry

conditions over the region.


Authors

Abstract


Applications

of sea-level

pressure

retrieval from

scatterometer

winds

University of Washington

Dr. Jerome Patoux

408 ATG Building

Box 351640

Seattle, WA 98195-1640

U.S.A.

[email protected]

Ralph C.

Foster

(University

of

Washington)

Robert A.

Brown

(University

of

Washington)

Contributed

Talk

Meteorology Five applications of

sea-level pressure

retrieval from

scatterometer winds using

the University of

Washington Planetary

Boundary Layer

(UWPBL) model are

presented: 1. Global

statistics of the UWPBL

pressure fields reveal

seasonal and hemispheric

differences with the

European Centre for

Medium-range Weather

Forecasts (ECMWF)

sea-level pressure

analyses. 2. The

enhancement of ECMWF

surface analyses over the

Southern Ocean by

injection of scatterometer-

derived sea-level pressure

wavelet coefficients

produces pressure fields

containing ~1% more

energy, 5-10% more low

pressure centers, an

extension of ~14% of the

midlatitude cyclone

tracks, deeper cyclones,

remove



tracks, deeper cyclones,

and more short-lived

mesoscale cyclones. 3.

The momentum flux into

the Southern Ocean is

larger when calculated

from the scatterometer-

modified ECMWF

analyses than when

calculated from the

original ECMWF

analyses. 4. Global

statistics of the surface

winds calculated from

scatterometer-derived

sea-level pressure fields

using the UWPBL model

show that the UWPBL

winds are of comparable

quality with DIRTH winds

in non-rainy areas and of

better quality than DIRTH

winds in rainy areas, as

compared to buoys and

ECMWF analyses. 5.

Scatterometer winds from

different instruments

(ASCAT vs. QuikSCAT)

are compared via the sea-

level pressure fields

retrieved with the

UWPBL model.


Authors

Abstract


Analysis of

the ASCAT

wind

inversion

residual:

Towards an

improved

C-band

Geophysical

Model

Function

Unidad de Tecnologia

Marina - CSIC

Dr. Marcos Portabella

Pg. Maritim de la

Barceloneta 37-49,

08003 Barcelona

Spain

[email protected]

Ad Stoffelen

(Royal

Netherlands

Meteorological

Institute)

Maria

Belmonte

(KNMI)

Anton Verhoef

(KNMI)

Jeroen

Verspeek

(KNMI)

Jur Vogelzang

(KNMI)

Contributed

Talk


and definitions

The Advanced

Scatterometer

(ASCAT) instrument,

a real aperture

vertically polarised

C-band radar with

high radiometric

stability, was

launched onboard

EUMETSAT’s

MetOp in October

2006. Within the

EUMETSAT

Satellite Application

Facilities (SAF), the

remove



(KNMI) Facilities (SAF), the

Royal Netherlands

Meteorological

Institute (KNMI) has

the responsibility of

the ASCAT level 2

wind production.

During the successful

calibration and

validation phase, in

which the instrument

has been precisely

calibrated and

outperforming in

terms of retrieved

wind accuracy,

several aspects of the

level 2 processing

were reviewed,

notably the forward

modeling, the Quality

Control (QC) and

the wind retrieval.

Several authors have

shown that a proper

characterization of

the scatterometer

inversion residual or

Maximum Likelihood

Estimator (MLE) is

very useful for

improving level 2

processing.

Following previous

experience with the

European ERS

scatterometer, we

normalize the

ASCAT MLE and

look into its

properties as a QC

indicator and wind

retrieval parameter.

Furthermore, we

show that by looking

at the normalized

MLE magnitude and

sign, one can identify

certain deficiencies in

the Geophysical



the Geophysical

Model Function

(GMF). This analysis

sets the grounds for

an improved C-band

GMF, i.e., CMOD6.


Authors

Abstract


Cross-

Validating

QuikSCAT

and

ASCAT

JPL/Cal Tech



Laboratory

4800 Oak Grove Dr.

Pasadena, CA, 91109

USA

[email protected]

Svetla

Veleva

(JPL)

R. Scott

Dunbar

(JPL)

Bryan

Stiles

(JPL)

Contributed

Talk


and definitions

The ASCAT on

MetOp series of

scatterometers

promises to be a long-

term source for ocean

vector wind data and a

complement to

QuikSCAT and future

US scatterometer

missions, as

recommended by the

NRC Decadal

Review. We have now

had close to one year

of joint operation of

QuikSCAT and

ASCAT, and the joint

data set presents a

unique possibility to

assess the relative

performance of the

two instruments. This

talk presents the work

conducted at JPL to

cross-validate and

compare the two

instruments. In the first

part, we present our

assessment of the

measurement

resolution and error

characteristics of both

instruments. As a first

step, we use traditional

validation methods,

such as comparing

against independent

ground truth and

models, and data

comparisons of space-

time coincident

remove



time coincident

QuikSCAT/ASCAT

data. We complement

these studies by

examining the spectral

resolution

characteristics of each

instrument. This

technique allows us to

estimate the instrument

resolution and noise

characteristics. In the

second part, we

examine the

geographical

distribution of

climatological mean

differences between

the two instruments

(after correcting for

diurnal variability). We

find different responses

for winds estimated

using Ku and C-

bands. Some of these

differences are

associated with Sea

Surface Temperature

fronts, while others

have basin scale

signatures. We

examine potential

sources of these

differences, including

instrumental biases,

rain contamination,

model function biases,

estimation biases, and

different surface

responses to wind and

wind stress at Ku and

C-band.



Progress in

Designing the

Next-

Generation

Scatterometer

JPL/Cal Tech



Laboratory

Robert Gaston (JPL)

Zorana Jelenak

(NOAA/NESDIS/STAR)

Paul Chang

(NOAA/NESDIS/STAR)

Contributed

Talk

Plans for

post-

QSCAT

era

The National

Research

Council in its

NRC Decadal

Review

remove



Scatterometer Laboratory

4800 Oak Grove Dr.

Pasadena, CA, 91109

USA

[email protected]

(NOAA/NESDIS/STAR) Review

recommended

that an

enhanced

performance,

next-generation

scatterometer,

the Extended

Ocean Vector

WindsMission

(XOVWM), be

launched in the

2013 to 2016

time frame. The

XOVWM

mission was

assigned to

NOAA, who

tasked the Jet

Propulsion

Laboratory

(JPL, the

designers of

QuikSCAT) to

explore

possible

designs for

future

scatterometer

missions. JPL

conducted an

intensive design

study, which

resulted in a

publicly

available report

to NOAA

detailing the

design,

performance,

and cost of

scatterometer

systems which

would make

progress in

meeting the

NOAA users

requirements,

while providing

data for future



data for future

ocean vector

wind science

studies. The

design and

performance

capabilities of

XOVWM and

QuikSCAT

continuity

missions were

favorably

reviewed.

NOAA

requested that

partners be

sought to help

realize a

scatterometer

system with

enhanced

measurement

capabilities

along the lines

of XOVWM.

The JAXA

GCOM-W2

mission,

scheduled for

launch in 2016,

represents a

potential

opportunity to

fly a

scatterometer

with higher

capabilities than

QuikSCAT

together with

the

complementary

AMSR sensor,

a combination

that showed

significant

benefits in the

ADEOS-II

mission.

Currently,

NOAA,



NOAA,

JAXA, and

JPL are

exploring the

accommodation

possibilities for

a next

generation

scatterometer

sensor on the

GCOM-W2

mission. These

studies include

a redesign of

the

scatterometer

instrument to fit

within the

constraints of

GCOM-W2,

and new

simulation and

performance

studies. In this

talk, we will

review the

history of the

XOVWM

since the

Amsterdam

OVWST

meeting, and

present the

expected

performance of

the XOVWM

concept and the

scatterometer

being studied as

the potential

payload for the

GCOM-W2

mission. In a

complementary

talk, NOAA

will present the

assessment of

the XOVWM

instrument by

their user



their user

community.


Authors

Abstract


Hurricane

Force

Extratropical

Cyclones as

Observed

by

QuikSCAT

NOAA/NWS/NCEP Ocean

Prediction Center

Mr. Joseph Sienkiewicz

5200 Auth Road

Camp Springs, MD 20746

USA

[email protected]

Joan Von Ahn

(NWS Office

of Services)

Michael J.

Brennan

(National

Hurricane

Center)

Khalil A.

Ahmad

(IMSG)

Cadet Shea G.

Wwinterberger

(USCGA)

Contributed

Talk

Meteorology The NASA

QuikSCAT scatterometer

provides near global

coverage of ocean

surface vector winds each

day. The combined

coverage of the

QuikSCAT instrument

and high retrievable wind

range to 40 m s-1 or

more in non-raining

conditions has

revolutionized the high

seas warning and short-

term forecast process at

the NOAA Ocean

Prediction Center (OPC).

OPC forecasters

routinely see the wind

field of entire cyclones,

including winds of

hurricane force using the

QuikSCAT wind fields.

To date we have learned

that hurricane force winds

are much more common

than thought. There are

preferred areas and times

of year for increased

frequency. The onset of

extreme conditions most

often occurs during the

rapidly deepening phase

of the cyclone and the

conditions are short lived

on average less than 24

hours in duration. This

talk will first present an

updated climatology of

hurricane force

extratropical cyclones

over the North Pacific

and North Atlantic

Oceans for the years

2001-2008. Secondly,

remove



2001-2008. Secondly,

we will present a

diagnostic examination of

the evolution of several

hurricane force

extratropical cyclones

using high temporal and

horizontal resolution

output from the

workstation Weather

Research and Forecast

(WRF) numerical model.


Authors

Abstract


On the

Sensitivity

of

Numerical

Simulated

Mesoscale

Air-sea

Coupling


Dr. Qingtao Song

College of Oceanic and

Atmospheric Sciences

104 COAS Admin Bldg

Corvallis, Oregon 97331

United States

[email protected]

Dudley

Chelton

(Oregon

State

University)

Steve

Esbensen

(Oregon

State

University)

Contributed

Talk

Meteorology It is well established from

satellite observations of near-

surface winds and SST from

QuikSCAT and the Advanced

Microwave Scanning

Radiometer, as well as from

numerical model simulations, that

near-surface winds in the

atmosphere are modified in the

vicinity of oceanic fronts

throughout the World Ocean.

However, the response of the

wind stress produced from

operational Numerical Weather

Prediction (NWP) models is

only about half as large as is

observed in the satellite data.

This study presents an analysis

of the sensitivity of simulated air-

sea coupling between mesoscale

surface winds and small-scale

SST variability to the resolution

of the SST boundary condition,

grid resolution, horizontal

diffusion, and vertical mixing. A

series of simulations were made

with the Weather Research and

Forecasting (WRF) model for

the Agulhas Return Current

(ARC) region in the South

Indian Ocean. We show that the

resolution and accuracy of the

SST boundary forcing and the

accuracy of model

parameterizations of vertical

remove



parameterizations of vertical

mixing in the marine atmospheric

boundary layer (MABL) are the

leading order factors in

determining the accuracy of

model simulations of this

coupling. It is found that the

weak coupling of surface wind

speeds from the ECMWF

model to SST is likely

attributable primarily to the

weak response of vertical

turbulent mixing to SST-induced

stability in the parameterization

of boundary layer turbulence.

Further sensitivity studies with

the WRF model found that the

entire atmosphere adjusts to the

forcing associated with the SST

front, with the largest changes in

wind speed near the bottom of

the MABL and vertical

propagation of wave motions

induced by the SST front.



Use of

Scatterometer

Winds in

Marine

Forecasting

ImpactWeather

Ms. Michelle Stewart

Houston, TX

USA

[email protected]

Dorri A. Breher

(ImpactWeather)

Contributed

Talk

Other Marine forecasting

differs from terrestrial

forecasting in both the

focus of the forecast

and the type of data

used to make a

forecast. Mariners are

concerned with wind

speeds, wave heights,

swell heights and any

type of precipitation

that may reduce

visibility. While

individual in situ

observation locations

are often few and far

between on the ocean,

QuikSCAT and

ASCAT winds give a

forecaster a spatially

dense view of the

current wind field which

in turn provides the

remove



in turn provides the

forcing over the ocean

surface producing

current wind-waves that

will eventually decay

and propagate into

swell. Marine

forecasters are in the

unique position to have

a highly detailed

scatterometer derived

depiction of the wind

field, normally at twelve

hour intervals, so they

can easily distinguish

and track synoptic

events such as fronts,

high wind areas or

tropical cyclones.

Empirical formulas are

used to calculate wind

wave heights from the

scatterometer wind

speeds. The depiction

of the wind-wave height

field can then be used

with known

propagation and decay

rates to estimate the

swell height twelve or

twenty-four hours in the

future. While model

swell data is available,

the model swell is only

as accurate as its initial

wind forcing and the

swell estimation

technique can be more

accurate in situations

where the model winds

differ greatly from

observed winds, such

as in tropical cyclones

or strong frontal

passages. Forecasters

at ImpactWeather use a

gridded map program

to assimilate model

data, calculate wind-

wave height and



wave height and

estimate swell height.

This program is then

used to provide a visual

wind and significant

wave height forecast

over a geographic area

as well as specific site

forecasts for any

location within the

gridded domain.


Authors

Abstract


A Dual

Frequency

Scatterometry

Approach for

Obtaining

Wind Speeds

in Hurricanes


Dr. Bryan Stiles

4800 Oak Grove Dr.

United States

[email protected]

Svetla

Hristova-

Veleva (Jet

Propulsion

Laboratory)

R. Scott

Dunbar (Jet

Propulsion

Laboratory)

Samuel

Chan (Jet

Propulsion

Laboratory)

Daniel

Esteban-

Fernandez

(Jet

Propulsion

Laboratory)

Stephen L.

Durden (Jet

Propulsion

Laboratory)

Ernesto

Rodriguez

(Jet

Propulsion

Laboratory)

W. Lee

Poulsen (Jet

Propulsion

Laboratory)

Robert W.

Gaston (Jet

Propulsion

Laboratory)

Contributed

Talk

Other We describe a method for

retrieving winds from co-

located Ku and C band ocean

wind scatterometers. The

method utilizes an artificial

neural network technique in

order to optimize the weighting

of the information from the two

frequencies and to use the

extra degrees of freedom to

account for rain contamination

in the measurements. A high

fidelity scatterometer

simulation is used to evaluate

the efficacy of the technique

for retrieving hurricane force

winds in the presence of heavy

precipitation. Realistic

hurricane wind and

precipitation fields were

simulated for three Atlantic

hurricanes, Katrina and Rita in

2005 and Helene in 2006,

using the Weather Research

and Forecasting (WRF)

model. These fields were then

input into a radar simulation

previously used to evaluate the

XOVWM dual frequency

scatterometer mission concept.

The simulation produced high

resolution, dual frequency

normalized radar cross-section

(NRCS) measurements. The

simulated NRCS

measurements were binned

remove



Laboratory)

and Phil

Callahan

(Jet

Propulsion

Laboratory)

measurements were binned

into 5 km by 5 km wind cells.

Wind speeds in each cell were

estimated using an artificial

neural network technique. The

method was shown to retrieve

accurate winds up to 50 m/s

even in intense rain. The

simulated results were

validated by comparision to

real world observations at

each step in the process. The

WRF fields were compared to

real observations of the

simulated hurricanes, the

estimated impact of the

precipitation on the NRCS

measurements was compared

to TRMM observations, and

the radar simulation was used

in conjunction with the

QuikSCAT ground processing

software to simulate

QuikSCAT retrieved wind

fields for comparison with

actual QuikSCAT winds. At

each step in the process the

simulation qualitatively and

quantitatively mirrored the

observed data.


Authors

Abstract


HIGH-

RESOLUTION

ASCAT

SCATTEROMETER

WINDS NEAR THE

COAST

KNMI

Dr. Ad Stoffelen

Postbus 201

3730 AE de Bilt

The Netherlands

[email protected]

Anton

Verhoef

(KNMI)

Marcos

Portabella

(CMIMA)

Contributed

Talk

New

products

In many applications winds

near the coast and at high

resolution are required.

Therefore, KNMI develops

ASCAT scatterometer wind

products at higher resolution

and nearer to the coast.

EUMETSAT currently applies

spatial averaging kernels to

suppress noise in the

measurements, which, on the

other hand, prevent wind

retrieval in coastal regions due

to their spatial extent. By

replacing the Hamming filter

kernels (i.e., cosine weighting

function) with a simple box (i.e.,

remove



function) with a simple box (i.e.,

constant weighting function over

a limited radial distance), we

can produce 25-km sampled

winds which do provide sea-

surface wind information up to

just 25 km off the coastline.

Moreover, these boxes may be

optimally chosen such that they

are located close to the

coastline, but still not

contaminated by land, and

maximize the number of wind

observations at shorter distance

off the coast. Later on, these

different swath gridding and

spatial averaging strategies will

be applied to the 12.5-km

product and processing may be

sustained at even shorter

distances to the coast down to

15 km. Different spatial

averaging strategies may allow

more noise in the L1 data and

thus in the L2 retrieved winds.

To suppress this random noise

KNMI has developed spatial

filtering techniques, which

maintain small-scale

meteorologically-relevant

spatially-coherent structures in

the resulting scatterometer wind

fields. This filter, by the so-

called Multiple Solution

Scheme (MSS) and 2-

Dimensional Variational

Ambiguity Removal (2D-

VAR), will be illustrated. The

MSS collects additional

information from the

scatterometer wind inversion

step, i.e., information on the

probability of all possible

winds, as retrieved from the

input local backscatter

measurements. This wind

vector probability distribution at

the swath grid is subsequently

used as input to the 2DVAR,

which provides a



which provides a

meteorologically balanced and

spatially coherent wind field.

The method may also be

applied on single-look SAR

data.


Authors

Abstract


OVERVIEW OF

AND

DEVELOPMENTS

IN THE

EUMETSAT

WIND

PRODUCTS

KNMI

Dr. Ad Stoffelen

Postbus 201

3730 AE de Bilt

The Netherlands

[email protected]

Anton

Verhoef

(KNMI)

Jeroen

Verspeek

(KNMI)

Jur

Vogelzang

(KNMI)

Marcos

Portabella

(CMIMA)

Maria

Belmonte

(KNMI)

Contributed

Talk

International

Collaboration

KNMI will present the

Level 2 scatterometer wind

processing of the

EUMETSAT Ocean and Sea

Ice Satellite Application

Facility (OSI SAF), the

EUMETSAT Numerical

Weather Prediction SAF and

the EUMETSAT Advanced

Retransmission Service

(EARS). In the NWP SAF,

scatterometer wind

processing portable software

packages are being made

available freely. In the OSI

SAF, currently four different

wind products are available:

SeaWinds 100-km product

(operational status),

SeaWinds 25-km product

(operational status), ASCAT

25-km product (pre-

operational) that may all be

viewed at

www.knmi.nl/scatterometer.

The EARS ERS-2 25-km

regional product

(demonstration) is available

within one hour and may be

used for weather nowcasting.

Tests are now ongoing for

EARS ASCAT dataavailable

within 30 min. Buoy

validation and monitoring

against a NWP model

reference are being

implemented for all products.

In the next ASCAT release in

November 2008 ASCAT

winds will be presented as

10m neutral winds for the first

remove



10m neutral winds for the first

time. Other developments on

sea ice and a level 4

scatterometer hi-res surface

wind product for the

MyOcean consortium will be

discussed at the meeting

TitleContact

Information

Other

Authors

Abstract


Rain

Influences

on High

Wind

Speed

Backscatter

Hofstra University

Dr. David Weissman

Department of

Engineering

104 Weed Hall

Hempstead, New

York 11549

U.S.A.

[email protected]

Mark A

Bourassa

(COAPS)

Contributed

Talk

Other Changes in the sea surface roughness

from the combined effects of wind and

rain, on scales of tens of kilometers, are

being studied using the QuikSCAT and

ADEOS-II/Seawinds scatterometers and

simultaneous NEXRAD three-dimensional

measurements of rain. Of particular interest

are the conditions with Hurricanes Isabel,

Claudette and Dennis. These results show

the dependence of the sea surface radar

cross section, at Ku-band, as a function of

the rainrate, wind speed and relative

direction, and polarization. The higher wind

conditions lead to large and distinctly

different changes in roughness and

backscatter for the two polarizations. The

unique method of this study is that it

combines the satellite based Ku-band data

with high-resolution 3-D volumetric rain

measurements, from simultaneous

collocated NEXRAD data. The volumetric

scans of this high resolution S-Band radar

are used to model the 3-dimensional Ku-

band reflectivity of the volume of

precipitation that the scatterometer beam

passes through as it samples the sea

surface. Consideration was also given to

the choice of rain drop-size-distribution

and the associated Z-R relation used for

the NEXRAD application. The choice of a

convective rain model had an appreciable

effect on the correction to each measured

QuikSCAT NRCS cell for rain attenuation

and rain volume backscatter. The removal

of these effects leaves the total contribution

of the sea surface; both the wind driven

and rain-impact roughness terms

Comparisons between the new high wind

results with those at lower wind speeds

show that when the speed approaches and

remove



show that when the speed approaches and

exceeds the terminal velocity of raindrops

in low wind conditions (about 8 m/s for the

larger drops) the surface roughness

features are distorted from the symmetric

properties that exist in still-air. This is

probably due to an increase in the speed

with which the larger raindrops impact the

sea interface.


Authors

Abstract


Improving

Satellite Wind

Measurements

Remote Sensing

Systems

Frank Wentz

438 First St

Suite 200

Santa Rosa, CA 95401

USA

[email protected]

Contributed

Talk


and definitions

Wind measurements

from satellites are vital to

climate research and

weather prediction. A

variety of satellite sensors

provide estimates of the

wind over the oceans by

measuring the sea-surface

roughness. These sensors

include scatterometers,

polarimetric radiometers,

and conventional

radiometers, the latter of

which provide only wind

speed. In the pursuit of

providing the community

with better satellite wind

products from all these

sensors, we focused on a

number of calibration and

algorithmic issues. First,

we're developing a new

retrieval algorithm for

conventional radiometers

(i.e., SSMI and AMSR)

that will provide useful

wind speed measurements

in storms and hurricanes.

The existing wind

algorithms for satellite

microwave (MW)

radiometers perform very

poorly in the presence of

rain, typically giving

spuriously high winds.

Paradoxically, NOAA's

primary airborne sensor

for measuring tropical

remove



for measuring tropical

cyclone wind speed is also

a MW radiometer: the

Step Frequency

Microwave Radiometer

(SFMR). We will report

some preliminary results of

the retrieval storm winds.

The second activity is the

precise calibration and

optimum interpolation of

WindSat observations.

WindSat is the first fully

polarimetric radiometer in

space. For a number of

reasons, the calibration,

data handling, sampling,

and retrieval algorithms for

WindSat are more

complex than for previous

radiometers. These

complexities have

somewhat masked the true

capabilities of this sensor.

We will present a number

of advanced methods for

processing the WindSat

observations. Other

activities include

redevelopment of the

QuikScat geophysical

model function (GMF) and

cal/val for the European

scatterometer ASCAT.

Now that we have nearly a

decade of QuikScat

observations, it seems

prudent to review the

QuikScat GMF and make

improvements where

necessary. We investigate

whether the amplitude of

the harmonics continues to

increase with wind speed

or does the relationship

flatten out. We also

explore the effect of ocean

currents on the buoy

versus QuikScat

intercomparisons used in



intercomparisons used in

the original GMF

derivations.


Authors

Abstract


Proposal for

the Ocean

Surface

Vector

Wind Virtual

Constellation

NOAA Satellite &

Information Service

Dr. Stan Wilson

1335 East West

Highway

SSMC-I Room 8110

Silver Spring, MD

20910

USA

[email protected]

Hans

Bonekamp

(EUMETSAT)

B.S. Gohill

(ISRO)

Contributed

Talk

Other The Ocean Surface Vector Wind

(OSVW) Virtual Constellation will

utilize satellite scatterometry to

collect observations of ocean

surface vector winds over the global

ice-free oceans. Standard OSVW

products will be generated from

scatterometers on multiple satellites

and made freely available to the

international community within

sufficient time for inclusion in

operational analyses and forecasts,

as well as use in retrospective

research. The key space segment

capabilities will include the following

polar-orbiting OSVW satellite

missions in orbit and under

development – QuikSCAT,

ASCAT on the METOP series, and

the scatterometers on OceanSat-2

and the HY-2 series of satellites –

as well as planned and proposed

future missions such as CFOSAT.

(See the figure on the following

page.) In addition to the space

segment, collaboration as part of

this Constellation will include on-

orbit calibration, the validation of

derived products, the determination

of consensus derived products and

formats, expediting the delivery of

those products to operational

forecast centers, collaboration in the

operational utilization of those

products and assessment of their

impact, and shared use in research.

remove

TitleContact

Information

Other

Authors

Abstract


Deep

atmospheric

structure

anchored by

IPRC,

University of

Hawaii

Hiroki

Tokinaga

(Hokkaido

University)

Contributed

Talk

Meteorology Significant surface wind modulation by

sea surface temperature (SST) fronts has

been extensively documented from

QuikSCAT. While such SST frontal

remove



surface wind

convergence

near major

ocean fronts

Professor

Shang-Ping Xie

IPRC, SOEST,

University of

Hawaii

1680 East

West Road,

Honolulu, HI

96822

USA

[email protected]

Shoshiro

Minobe

(Tokyo

University

of Marine

Science and

Technology)

and Fumiaki

Kobashi

(Japan)

effects are often trapped in the

atmospheric boundary layer (ABL), our

recent studies show that they may extend

into as deep as the upper troposphere,

along the Gulf Stream in the North

Atlantic, the Kuroshio Extension and

subtropical countercurrent in the

Northwest Pacific. The Gulf Stream affects

the entire troposphere. In the ABL,

atmospheric pressure adjustments to sharp

SST gradients lead to surface wind

convergence that anchors a narrow

precipitation band along the Gulf Stream.

In this rain band, upward motions and

cloud formation extend into the upper

troposphere as corroborated by the

frequent occurrence of very cold cloud-top

temperatures. These mechanisms offer a

direct pathway by which the Gulf Stream

can affect the atmosphere both locally and

possibly in remote regions via planetary

wave propagation. Similarly, the Kuroshio

Extension anchors a surface convergence

zone, along which the cloud top is

significantly higher in altitude than the

surroundings. The North Pacific

subtropical countercurrent (STCC) is an

eastward current, against not only the

southeast trades as well as the westward

flow predicted by the Sverdrup theory.

Potential vorticity gradients of thermocline

water subducted in winter are considered

to cause this peculiar current. The

QuikSCAT climatology reveals that the

SST front of the STCC anchors a zonal

band of weakly positive curls in the midst

of prevailing negative curls. This band of

positive wind curls is associated with a

deep moist layer in the atmosphere and

frequent genesis of sub-synoptic cyclones,

possibly due to enhanced atmospheric

baroclinicity. The deep atmospheric

influence is most pronounced during April-

May when SST gradients are still strong

and SST on the warm flank of the STCC

front is high enough and conducive to

atmospheric convection.

Contact Other Abstract



TitleContact

Information

Other

Authors

Abstract


Introducing

the WHOI

OAFlux

global

0.25-

degree

ocean

vector

wind

analysis

(1987-

present)

Woods Hole

Oceanographic

Institution

Dr. Lisan Yu

Department of

Physical

Oceanography

Woods Hole

Oceanographic

Institution

Woods Hole,

MA 02543

USA

[email protected]

Contributed

Talk

Plans for

post-

QSCAT

era

A new global ocean surface vector wind analysis

with 0.25 degree resolution is now available for

20+ years from mid 1987 to present. The products

include 10-m surface wind (zonal and meridional

components and wind speed), wind stress, and

wind stress derivative (curl and divergence) fields,

and are developed by the Objectively Analyzed

air-sea Fluxes (OAFlux) project at WHOI. The

OAFlux surface wind products were constructed

not from a single data source, but from an objective

analysis of multiple passive and active microwave

sensors (SSM/I, NSCAT, QuikSCAT, AMSR-E)

and three atmospheric wind reanalyses. The

reanalyzed winds provided directional information

for passive microwave wind speed retrievals

whenever scatterometer measurements are lacking.

Validation of the datasets was made with 100+ in

situ buoy time series measurements. The OAFlux

surface wind products are developed in parallel

with the development of ocean evaporation, latent

and sensible heat fluxes, and radiative fluxes for

eventual establishment of a complete database for

global ocean surface forcing for the satellite era.

These consistent air-sea momentum, heat, and

freshwater products provide consistent global

patterns that facilitate the construction of the

correlations between various air-sea interaction

processes and of the teleconnection pattern

between weather and climate anomalies in one

region and those in another. All these studies will

lead to improved understanding of the ocean’s

feedback mechanisms to changes in air-sea

physical forcing on various timescales include

synoptic, seasonal, interannual, decadal and longer.

Results presented in this study will demonstrate the

use of OAFlux wind analysis in understanding air-

sea interactions during the tropical and mid-latitude

storm events.

remove


Authors

Abstract


Combined

Active and

Passive

Microwave

Remote

Sensing of

High

Jet Propulsion

Laboratory, California

Institute of Technology

Dr. Simon Yueh


Pasadena

Julian

Chaubell

(Jet

Propulsion

Laboratory)

Contributed

Talk

Other

science or

operations

To assess the capability of

combined active and passive remote

sensing for high ocean winds, we

analyzed the data from WindSAT,

ASCAT, and QuikSCAT for several

Atlantic Hurricanes in 2003-2008.

The WindSAT data from 20

remove



High

Ocean

Winds

Pasadena

California, 9109

USA

[email protected]

The WindSAT data from 20

hurricanes were collocated with the

NOAA HWind analyses. The

WindSat 6-GHz brightness

temperatures (TB) were less affected

by rain than the high frequency

channels, and were mostly far from

saturation near the hurricanes. The

differences between vertical and

horizontal polarizations were quite

significant, indicating the

characteristics of surface emissions,

rather than rain attenuation. The

excess surface emissivity at the C-

band frequency appears to be

consistent with the SFMR model

with about 0.5K-1K change in TB

for 1 m/s change in wind speed. For

ASCAT backscatter analysis, 30

revs of ASCAT data were

collocated with the HWind analyses.

The ASCAT data at 50-60 degree

incidence angles showed weak wind

speed response, about 1 dB change

from 30 m/s to 50 m/s. The

comparisons show that the ASCAT

backscatter levels are in good

agreement with the CMOD5 model

function for < 15 m/s, but can be

below the CMOD5 model by 1-2

dB for 15-50 m/s wind speeds.

From the analysis of microwave

propagation through rain, we

determined that the 1-2 dB

discrepancy is within the attenuation

range of precipitation near

hurricanes. It is suggested that the C-

band ASCAT backscatter, although

less sensitive to precipitation than

Ku-band, will still require rain

attenuation correction to reduce the

wind speed bias. We evaluate the

synergism of combining active and

passive data through the wind

retrievals using the QuikSCAT data

only and the addition of WindSAT

data. We find that including the

WindSAT polarimetric data in the

retrieval allows the reduction of wind

solution ambiguities, improvement in



solution ambiguities, improvement in

directional accuracy and

consequently improvement in wind

speed accuracy for high ocean

winds.



Preliminary

Evaluation

of ASCAT

Ocean

Surface

Vector

Wind

(OSVW)

Retrievals

at NOAA

Ocean

Prediction

Center

NOAA/NESDIS/StAR

Dr. Khalil Ahmad

NOAA Science Center

5200 Auth Road

Camp Spring, MD

20746

USA

[email protected]

Joseph Sienkiewicz

(NOAA/NWS)

Zorana Jelenak

(NOAA/NESDIS/StAR)

Paul Chang

(NOAA/NESDIS/StAR)

Either

Talk or

Poster

Other

science or

operations

The NOAA Ocean

Prediction Center is

responsible for issuing

marine forecasts and wind

warnings over the North

Atlantic and North Pacific

extratropical high seas,

including the offshore

waters of the continental

United States. High quality

OSVW data from

QuikSCAT have proven

to be an extremely useful

data source in OPC's

daily forecast and warning

operations. A new source

of OSVW data has

become available after the

recent launch of the

ASCAT instrument.

OSVW retrievals from

ASCAT are produced by

NOAA NESDIS, and are

being routinely viewed by

OPC forecasters on a

daily basis during the

course of their operational

shifts. In this presentation

we provide an overview

of the ASCAT

measurement

characteristics, and the

instrument spatial /

temporal coverage.

Further, we present an up

to date assessment of the

ASCAT retrievals in

support of OPC's analysis

and warning operations,

where we focus on the

utility of the ASCAT

OSVW data in detecting

remove



OSVW data in detecting

Hurricane Force (HF)

extratropical cyclones,

and estimating the wind

warning category. In this

activity, we utilize the

surface analysis charts

prepared by the OPC

forecasters to locate and

track all HF extratropical

cyclones observed over

both the North Atlantic

and North Pacific oceans

during the 2007/2008

hurricane season.

Hundreds of passes from

ASCAT and QuikSCAT

are examined, and wind

retrievals are compared to

the output of two

Numerical Weather

Prediction models, and

where available, to

conventional buoy / ship

observations. Results

indicate that ASCAT can

reliably retrieve low to

moderate surface wind

speeds in all weather

conditions. This

performance represents an

improvement over

QuikSCAT, which suffers

from an artificially rain

inflated retrievals in areas

of rain. However, for

higher wind speeds,

ASCAT retrievals are

found to have a low wind

speed bias, which

degrades ASCAT

capability in detecting

extratropical cyclones with

Hurricane Force

conditions.



Application of

satellite

NOAA/AOML J. Ardizzone

(NASA/GSFC)

Either

Talk or

Meteorology This talk will document the

development and validation of a

remove



satellite

surface wind

data to ocean

surface wind

analysis and

nwp

Dr. Robert Atlas

NOAA Atlantic

Oceanographic and

Meteorological

Laboratory

4301 Rickenbacker

Causeway

Miami, FL 33149

USA

[email protected]

(NASA/GSFC)

J.C. Jusem

(NASA/GSFC/)

R.N.Hoffman

(AER)

M.Leidner

(AER)

S. Majumdar

(Univ. of Miami)

S.Chen (Univ.

of Miami)

B-W. Shen

(NASA/GSFC)

Talk or

Poster

development and validation of a

new high resolution, cross-

calibrated, multi-platform

satellite surface wind data set

for both meteorological and

oceanographic applications,

recent Quikscat and ASCAT

data impact experiments, and

the use of Quikscat data in the

development of very high

resolution global atmosphe4ic

models.


Authors

Abstract


Metop-

B Orbit

Phasing

Proposal

EUMETSAT

Dr. Hans Bonekamp

Am Kavelleriesand 31

D-64297 Darmstadt

Germany

[email protected]

Bonekamp H

(EUMETSAT)

Wilson JJ

(EUMETSAT)

Figa-Saldana J

(EUMETSAT)

Anderson C

(EUMETSAT)

Either

Talk or

Poster

Other The definition of the Metop-B

launch and LEOP service requires

an early selection of the orbit

phasing between the METOP-A

and METOP-B satellites.

Analyses of the constraints,

requirements and preferences of

the system and of the various

instruments have been performed

for and presented to

EUMETSAT delegate bodies.

This has resulted in a consolidated

baseline proposal of 48.93min.

An overview of the constraints

and requirements and the impact

on ASCAT global coverage is

presented.

remove


Authors

Abstract


The impact

of

atmospheric

boundary

layer

stability on

the 2-6.5

day

variability of

the 10m

meridional

winds.

University of Washington

Department of Atmospheric

Sciences

Mr. Jimmy Booth

408 ATG Building, box

351640

Seattle WA 98195-1640

United States of America

[email protected]

LuAnne

Thompson

(UW-

Oceanography)

Kathie Kelly

(UW-APL)

Jerome Patoux

(UW-Atmos

Sci)

Suzanne

Dickinson

(UW-APL)

Either

Talk or

Poster

Meteorology To isolate baroclinic

wave activity, time filtering

is applied to the meridional

winds at 10 meters (m) and

850 millibars (mb) over the

Northern Hemisphere

Atlantic and Pacific

Oceans, and the Southern

Ocean. The standard

deviation of the time filtered

winds is calculated for the

winter months during the

QuikSCAT period using

remove



ECMWF winds. After

verifying that the ECMWF

model yields an adequate

representation of the

variability in the surface

winds for this time period,

ECMWF fields are used to

allow examination of

atmospheric fields away

from the surface. At 850

mb, the standard deviation

of meridional winds yields

the atmospheric storm

tracks. The spatial structure

can be reproduced using

other atmospheric variables

aloft, such as the 300 mb

height field. These patterns

capture the regions of large

baroclinic wave activity,

and correspond to the

regions of heavy

occurrence of midlatitude

storms. At 10 m, the

pattern differs from the

storm track aloft. The

standard deviation of the

time filtered 10m meridional

wind has a maximum south

of the maximum aloft.

These differences can be

explained by the

preferential mixing down of

momentum in regions in

which atmospheric

boundary layer (ABL)

instability is large. The

region of strong ABL

instability corresponds to

the region of the storm

track entrance. The mixing

down of strong winds

enhances the surface fluxes

in these regions, seeding the

storm tracks with warm

moist air.


Authors

Abstract




Calibration

and

validation

of ASCAT

backscatter

EUMETSAT

Ms. Julia Figa-Saldana

Am Kavalleriesand 31

64295 Darmstadt

Germany

[email protected]

C. Anderson

(EUMETSAT)

J. Wilson

(EUMETSAT)

H. Bonekamp

(EUMETSAT)

A. de Smet

(EUMETSAT)

C. Duff

(EUMETSAT)

Either

Talk or

Poster


and definitions

The Advanced

Scatterometer (ASCAT)

on METOP-A is real

aperture, vertical

polarisation, C band radar.

It has been designed with

the primary objective of

providing near surface

winds over the global

oceans in all weather

conditions. Winds are

retrieved using a model

from the primary

measurement of the radar,

the surface normalized

radar cross section

(sigma0), which is

provided over two swaths

of 550 km at both sides of

the satellite ground track,

at approximately 50 and

34 km resolution, on a 25

km and 12.5 km swath

grid spacing, respectively.

Three finely calibrated

ground transponders

located in Turkey provide

a means of sending to the

ASCAT point target

signals with a precisely

known cross section. As

the position of the

transponders is also very

precisely known, this

provides a fine sampling of

the antenna gain patterns of

all six beams. These data

are used to fit an antenna

gain model to achieve the

absolute calibration of the

radar. This paper describes

the calibration process and

the accuracy levels

achieved. ASCAT is a

successor instrument to the

Active Microwave

Instruments on ERS-1 and

2 and shares the same

beam geometry,

polarisation and almost the

remove



polarisation and almost the

same radar frequency.

Research using data from

ERS-1 and 2 has resulted

in a number of accurate

backscatter models for

ocean, sea ice and

rainforest regions of the

Earth. We describe how

these models are used with

ASCAT data to confirm

the calibration levels and to

monitor the instrument

stability in between

transponder calibration

campaigns.

TitleContact

Information

Other

Authors

Abstract


Wind

Vector

Retrievals

under Rain

with Passive

Microwave

Radiometers

Remote Sensing

Systems

Dr. Thomas Meissner

438 First Street,

Suite 200

Santa Rosa, CA

95401

USA

[email protected]

Frank

Wentz

(Remote

Sensing

Systems)

Either

Talk or

Poster

Plans for

post-

QSCAT

era

We have developed algorithms that

retrieve ocean surface wind speed and

direction under rain using brightness

temperature measurements from passive

microwave satellite radiometers. For accurate

radiometer retrievals of wind speeds in rain it

is essential to use brightness temperature

signals at different frequencies, whose

spectral signature makes it possible to find

channel combinations that are sufficiently

sensitive to wind speed but little or not

sensitive to rain. The wind speed retrieval

accuracy of an algorithm that uses C-band

frequencies and is trained for tropical

cyclones ranges from 2.5 m/s in light rain to

3.5 m/s in heavy rain. We have also trained

and tested a global algorithm, that is less

accurate but can be applied under all

conditions. Its estimated accuracy is between

2.5 m/s in light rain and 5.5 m/s in heavy rain.

The wind direction retrieval accuracy

degrades from about 10o in light rain to 25o

in moderate – heavy rain. We compare the

performance of wind vector retrievals under

rain from microwave radiometers with those

from scatterometers and discuss advantages

and shortcomings of both instruments. We

also analyze the wind induced sea surface

emissivity including its wind direction

dependence at high wind speeds up to 40

m/s, which are generally only present under

remove



m/s, which are generally only present under

rain.


Authors

Abstract


Improving ENSO

forecasts by

adding weather

regimes observed

from QuikSCAT in

oceans/atmosphere

climate models

Caltech/Jet Propulsion

lab

Dr. Claire Perigaud


Pasadena

CA91109-8099

USA

[email protected]

Joseph

Dureau

(Caltech-

JPL)

Serena Illig

(IRD-

LEGOS)

Christophe

Cassou

(CNRS-

CERFACS)

Either

Talk or

Poster

Oceanography Weather regimes are

determined from classifying

TRMM and QuikSCAT

data between 2000 and

2006. The regime

occurrence is first added to

the coupling of an Indian

Ocean/Tropical

Atmiosphere/Land model.

Because the Indian Ocean

resonates at the semi-annual

period and harmonics, the

weather-fed ocean gains

energy in the MJO range,

impacting the atmosphere all

around the Planet. Similarly

the addition of QuikSCAT

regimes to the coupling of an

ENSO model is efficient to

improve the forecasts of

seaonal-to-interannual

changes. However success

depends on the basin-wide

budgets of sea level in quasi-

Sverdrup balance with the

wind stress over the Indian

and Pacific oceans. Due to a

permanent basin-wide stress

torque in QuikSCAT that

differs from any other OVW

product, using QuikSCAT

for model initialization

systematically leads to

degradation of ENSO

forecasts. FSU ship winds

are the OVW data set which

best simulates the basin-

wide budgets. It performs

better than ECMWF or

NCEP because the latter

have unrealistically weak

meridional components.

Thus QuikSCAT and FSU

are needed for the

monitoring of local wind

remove



monitoring of local wind

bursts and large scale stress

respectively. Why is FSU

data set the best performer

at large scale? Do their

stress vectors contain

climate changes of swell that

need to be taken into

account in the forcing of

ocean models?


Authors

Abstract


Biweekly

Oceanic and

Atmospheric

Tropical

Instability

Waves: are

they forced?

coupled? or

resonant

with the

Moon?


lab

Dr. Claire Perigaud


Pasadena

CA91109-8099

USA

[email protected]

Either

Talk or

Poster

Oceanography Various Indian Ocean models

forced by different OVW products all

simulate tropical instability waves

(TIWs) in the [10-to-40 day] range.

Interestingly since QuikSCAT OVW

stress products are used to force

ocean models, the bi-weekly TIWs

became prominent, especially in the

Indian and Atlantic oceans. Indeed the

size of the Indian and Altnatic basins

favors the the bi-weekly period as

Yanai waves propagate at ~2m/s from

one side of the basin to the other in

one cycle at this period. Is the source

of biweekly instability in the ocean or

in the atmosphere? Ocean models

forced by QuikSCAT simulate cross-

equatorial currents lagging the wind

reversals. But it is hard to validate the

TIW phase simulated by ocean models

with independent observations. In

addition bi-weekly TIWs are observed

in the atmosphere too. These waves

can be self-generated by atmospheric

instabilities too, they occur in

convective regions over the warm pool

and Yanai waves propagate ten times

faster in the atmosphere than in the

ocean waves at this period. So

atmospheric TIWs reach the Indian

Ocean at times when one cannot

separate the phase of the bi-weekly

ocean signals from the atmosphere nor

at their interface. With a weaker

amplitude, we find that biweekly

oceanic TIWs are indeed present

throughout all the Pacific ocean too.

remove



throughout all the Pacific ocean too.

So, we examine if the source of

biweekly fluctuations in all 3 oceans

and atmosphere could be the migration

of the Moon North and South of the

equator in 14 days, and we analyze the

occurence of the QuikSCAT bi-

weekly cross-equatorial fluctuations as

a function of the Lunar Phase.


Authors

Abstract


Validation

of High

Resolution

Coastal

Winds


Dr. Barry Vanhoff

104 COAS Admin Bldg


Corvallis, OR 97331-5503

USA

[email protected]

Dr.

Michael

Freilich

(Oregon

State

University)

Either

Talk or

Poster


and definitions

Limited field data

and regional

atmospheric model

results suggest that

systematic wind

patterns with cross-

shore scales smaller

than 50 km are

prevalent in the

nearshore region near

mountainous coasts and

islands. Ekman pumping

from these small-scale

winds contributes

substantial forcing to the

coastal ocean. Current

high (12.5km)

resolution scatterometer

data products use a 20-

km land mask which

preclude their use for

investigating nearshore

wind patterns and the

connections between

coastal and larger-scale

ocean winds. Although

higher resolution

scatterometer wind

retrievals have been

produced, these

experimental data sets

have not been

rigorously validated – in

particular, their

coverage limitations

near land have not been

determined objectively,

and their accuracies in

remove



and their accuracies in

the coastal zone have

not been quantified.

This investigation will

validate a full-mission,

high-resolution 12.5km

scatterometer data

product generated at

OSU which uses a

refined wind retrieval

algorithms and a new

empirical land mask.

Analyses of backscatter

statistics from

QuikSCAT sigma0

slice measurements are

used to establish an

objective location- and

geometry-dependent

empirical land mask

(nominally < 20-km),

and winds have been

re-retrieved as

necessary to ensure

maximum nearshore

coverage while

excluding land-

contaminated

measurements.

Operational NDBC

buoys are used to

quantitatively

characterize the

accuracy of the high-

resolution vector wind

measurements in the

coastal zone.

TitleContact

Information

Other

Authors

Abstract


Status of

GCOM and

expectation

for

microwave

scatterometer

Earth Observation

Research Center /

JAXA

Dr. Keiji Imaoka

2-1-1 Sengen,

Tsukuba, Ibaraki

305-8505 Japan

Japan

[email protected]

Misako

Kachi

(Japan

Aerospace

Exploration

Agency)

Tamotsu

Igarashi

(Japan

Aerospace

Invited Other Japan Aerospace Exploration Agency

(JAXA) is pursuing the Global Change

Observation Mission (GCOM). GCOM

will consist of two series of medium size

satellites: GCOM-W (Water) and

GCOM-C (Climate). The mission will

take over the Advanced Earth Observing

Satellite-II (ADEOS-II) and develop into

the long-term observation. The

Advanced Microwave Scanning

remove



[email protected] Aerospace

Exploration

Agency)

Keizo

Nakagawa

(Japan

Aerospace

Exploration

Agency)

Naoto

Ebuchi

(Institute of

Low

Temperature

Science -

Hokkaido

University)

Taikan Oki

(Institute of

Industrial

Science -

The

University of

Tokyo)

Haruhisa

Shimoda

(Tokai

University

Research

and

Information

Center)

Advanced Microwave Scanning

Radiometer-2 (AMSR2) for the

GCOM-W1satellite, which is the first

satellite of GCOM, is now under

development. The second satellite of

GCOM will be GCOM-C1, which will

carry the Second-generation Global

Imager (SGLI). AMSR2 is being

developed based on the experience of

the AMSR for the EOS (AMSR-E),

which is currently in operation on the

EOS Aqua satellite. The instrument is a

dual-polarized total power microwave

radiometer system with six frequency

bands ranging from 7GHz to 89GHz.

Major changes in performance from

AMSR-E include the larger antenna

diameter of 2.0m for better spatial

resolution, additional 7.3GHz channels

for mitigating radio-frequency

interference, and improvements of

calibration system. The GCOM-W1

satellite system is now in Phase-C. We

expect a long-term continuity by leading

the AMSR2 to the current AMSR-E

observation that has been accumulating

six years of data records. Current target

launch year of GCOM-W1 is the

beginning of 2012. Although an important

science requirement for GCOM-W1 was

to install a microwave scatterometer

together with the radiometer for

observing various oceanic and weather

phenomena, it was not the case for the

GCOM-W1 satellite. JAXA and

Japanese science community began

discussing science requirements for

GCOM-W2, the second generation of

GCOM-W series. Installing a

scatterometer again an important

requirement for GCOM-W2. Many

synergy effects are expected covering not

only instrument-level advantages but also

scientific-level merits. At the meeting, we

will present the status of the GCOM

program and our expectation for installing

a microwave scatterometer on GCOM-

W2.




Authors

Abstract


NASA

Headquarters

Overview

NASA Headquarters

Dr. Eric Lindstrom

300 E Street SW

Washington, DC

20546

USA

[email protected]

Invited Other Overview of NASA Earth Science

Division activity as it relates to the

Ocean Vector Winds Science Team.

Status of Decadal Survey Mission

studies related to ocean vector winds.

Status of international collaborations on

OVW missions. Discuss timing and

scope of re-competition of OVWST in

2009.

remove


Authors

Abstract


Uncertainties

in OVW

stress

estimations

from

scatterometers

and

ocean/climate

consequences


lab

Dr. Claire Perigaud


Pasadena

CA91109-8099

USA

[email protected]

Abderrahim

Bentamy

(CERSAT)

Invited Oceanography We report difficulties that

oceanographers face when using

the stress vectors produced so far

from scatterometer data. First

month-to-multiyear averaged

planetary budgets of zonal and

meridional components issued

from collocated data are

compared. These budgets reveal

significant differences between

satellites. Using speeds and

direction for calibration/validation

can be misleading because of the

anisotropy of the large scale

climate circulations of both fluids.

Regardless of the drag formula

used to convert winds, the stress

vectors derived from

scatterometers systematically

contain basin-wide torques which

differ from all other estimates

derived from the atmosphere.

This is so because the latter does

not contain the signature of ocean

currents, swell and wind waves

like the satellites. The ocean

contribution to seasonal and

interannual changes of surface

winds is far from negligible

relative to those induced by the

atmosphere only. When we

estimate stress vectors after

having converted sigma0 into

wind speeds and directions, we

make systematice large scale curl

remove



make systematice large scale curl

errors that have significant impact

on the ocean circulation simulated

by climate models. So to monitor

oceans and climate from

scatterometers, we need Level

2B geophysical quantities other

than winds. Preliminary results

estimated in terms of ocean wind

work are presented.

<< [1] >>

Go back.



Documents

NASA Ocean Vector Wind Science Team Meeting · 2009-06-05 · NASA Ocean Vector Wind Science Team Meeting Click here to view a list of all the participants Click here to go back Displaying