Application of HYCOM in Eddy-Application of HYCOM in Eddy-Resolving Global Ocean Resolving Global Ocean

PredictionPrediction

Community Effort:Community Effort: NRL, Florida State, U. of Miami, GISS, NOAA/NCEP, NOAA/AOML, NOAA/PMEL, PSI,

FNMOC, NAVOCEANO, SHOM, LEGI, OPeNDAP, UNC, Rutgers, USF, Fugro-GEOS, Orbimage, Shell,

ExxonMobil Presented by Harley HurlburtPresented by Harley HurlburtNaval Research LaboratoryNaval Research Laboratory

Stennis Space Center, MS USAStennis Space Center, MS USA

International GODAE Steering Team MeetingInternational GODAE Steering Team MeetingSt. Johns, Newfoundland, Canada St. Johns, Newfoundland, Canada

7-9 August 20077-9 August 2007

Part of HYCOM/GODAE project sponsored by the National Ocean Partnership Program

Global Product Mid-Lat

Resolution

Vert. Coord.

Inputs Run By Actual or Target

Date

1/16 NLOM 7 km Layered

SSH, SST,

hydro, FNMOC

NOGAPS

Atmospheric

Forcing

NAVO OP 9/01-3/06

1/8 NCOM 1 15 km /z NAVO OP 2/06

1/32 NLOM 2 3.5 km Layered NAVO OP 3/06

1/12 HYCOM 3,5 7 km //z NAVO 2007

1/25 HYCOM 3.5 km //z NAVO 2011

Near Real-time demonstration

1/12 Atl. HYCOM 4,5 7 km //z NRL 2002

U.S. Navy Present and Planned Global Ocean Prediction Systems

OP = operational 1 High vertical resolution for mixed layer prediction. Assimilates SSH from NLOM via T and S synthetic profiles. Web page http://www.ocean.nrlssc.navy.mil/global_ncom2 Web page http://www.ocean.nrlssc.navy.mil/global_nlom3 Running in real time at NAVO. 4 Under the National Ocean Partnership Program (NOPP), 1/12 Atlantic HYCOM demo is running in near real-time. Includes the Mediterranean Sea. 5 Results at http://www.hycom.org (100Tb LAS server at FSU)

Results from Real-Time 1/12Results from Real-Time 1/12 Global Global HYCOM with NCODA Data AssimilationHYCOM with NCODA Data Assimilation

Sea Surface Height (SSH) in cm

NW Pacific SSH zoom on 12 Mar 2007 NAVOCEANO operational analysis of the Kuroshio front based on satellite AVHRR imagery is overlaid black segments are based on imagery > 4 days old

Global SSH on 23 Mar 2007Gray areas are ice covered

Sequential Incremental Update Cycle Analysis-Forecast-Analysis

MVOI - simultaneous analysis 5 ocean variables temperature, salinity, geopotential, velocity (u,v)

Ocean modelHYCOM

Ocean data QC

Ocean dataAnalysis3D MVOI &

Cooper-Haines

Ocean obs

SST: GAC/LAC MCSST, GOES, Ship, Buoy Profile: XBT, CTD, T & S profiling Floats (ARGO), Fixed Buoy, Drifting Buoy Altimeter SSHA SSM/I Sea Ice

Innovations

Increments

Forecast Fields Prediction Errors

First Guess

NRL Coupled Ocean Data Assimilation (NCODA)

NCODA Observation Locations

1/12º Global HYCOMSSH and surface drifters in the Kuroshio Region

1/12º Global HYCOMSSH and surface drifters in the Kuroshio Extension

WorldOcean Gulf Stream

Persian Gulf

EquatorialPacific Kuroshio Taiwan

1.0

0.9

0.8

0.7

1.0

0.9

0.8

0.7

0.6

Med

ian

SS

H a

no

mal

y co

rrel

atio

n

0 10 20 30 0 10 20 30 0 10 20 30

Forecast length (days)

Forecast Verification Statistics from 1/12Forecast Verification Statistics from 1/12 Global Global HYCOMHYCOM

16 Forecasts included in statistics* Operational forcing reverts toward climatology at the end

of the atmospheric forecast.

Atmospheric analysis forcing operational forcing* persistence

Nesting Strategy for Ocean Prediction

Global Regional Littoral Nearshore Near-term: through FY04 in R&D, FY04-FY08 operational, including transition 1/8 NCOM NCOM or SWAFS NCOM or SWAFS ADCIRC 15-16 km mid-lat resolution

4 - 8 km, larger regions

< 1 to 2 km res < 2 km resolution finite element

Mid-term: FY04 - FY08 in R&D, FY08 – FY12 operational, including transition 1/12 HYCOM HYCOM *NCOM or HYCOM ADCIRC 7 km mid-lat resolution

2 - 4 km, smaller regions

.5-1.5 km res < 1.5 km res

Long-term: FY09-FY12 in R&D, FY12 and beyond operational, including transition +1/25 HYCOM

Regional generally not needed

*NCOM or HYCOM ADCIRC

3 - 4 km mid-lat resolution

Not used 1km res 1 km res

*Hogan and Kindle CO-NESTS project will provide research results needed to make the

appropriate choice. An alternative model such as ROMS may also be considered. +1/25 HYCOM gives useful littoral resolution globally

Model Evaluation: Regional NCOMModel Evaluation: Regional NCOM

NCOM Regional (CCS) with SeaWifs

Chlorophyll

NCOM CCS

9 Km

J. Kindle (NRL)

Model Evaluation: Tide GaugesModel Evaluation: Tide Gauges

Global NCOM and HYCOM

Regional NCOM: Forced by NCOM and

HYCOM

Global HYCOM and NCOM nest represent Coastal Kelvin Wave Pulses More Accurately

J. Kindle (NRL)

Model CorrelationHYCOM .87NCOM .77

Boundaryvalues from CorrelationHYCOM .86NCOM .75

1Classes of Ocean Response to Atmospheric Forcing

Class Examples Implications 1. Strong, rapid (< a week), and direct

Surface waves, storm surges, and rapid variations within the upper mixed layer, beneath hurricanes, in coastal and equatorial upwelling, and often the onset of equatorial and coastal trapped waves

Forecasts are short range; limited by atmospheric predictive skill. Less sensitive to errors in the initial state; more sensitive to errors in forcing

2. Slower (weeks to months) and indirect

Mesoscale eddies, meandering currents, frontal locations, features related to flow instabilities on the mesoscale

Forecast skill up to a month or more; more sensitive to errors in the initial state; less sensitive to errors in forcing; ocean data assimilation is essential; variability statistics may be predicted via simulation

3. Slow (weeks to years) direct integrated response

El Nino; much of the tropical ocean circulation, gyres, persistent features associated with geometric and topographic constraints

Long range forecasts possible; sensitive only to errors in forcing on long time scales; nowcasting and forecasting feasible using ocean models with sparse ocean data

4. Free propagation of existing features (weeks to years)

Equatorial and coastal trapped waves, Rossby waves and stable isolated eddies generated under Classes 1, 2, and 3

Reduced sensitivity to onset mechanisms and extended forecast skill, weeks to years

1A 5th class includes tides and tsunamis that are (mostly) not in response to the atmosphere. Other classes are not considered here, e.g. most inertia-gravity waves and fine-scale flow instabilities that may result from atmospheric forcing. From Hurlburt et al. (2007); adapted from Hurlburt (1984).

Nested Shallow Water Forecasting Requirements To forecast Class 1 and Class 4 phenomena, a nested coastal

model needs the following more than ocean data assimilation - Accurate ocean model - Accurate atmospheric forcing - Accurate bottom topography - Accurate boundary conditions from a large scale model

o Outermost model with the finest resolution possible o Multiple nesting degrades accuracy

Memory of assimilated ocean data is quickly lost

- Adjoint valuable tool to maximize data impact - Ocean data is essential to evaluate and improve models