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Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System Gary Lagerloef Aquarius Principal Investigator AA/CPO Climate Observation Division 6th Annual System Review 3-5 September 2008 Silver Spring, MD

Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

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Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System. NOAA/CPO Climate Observation Division 6th Annual System Review 3-5 September 2008 Silver Spring, MD. Gary Lagerloef Aquarius Principal Investigator. AQUARIUS/SAC-D Science Workshop Puerto Madryn, Argentina, - PowerPoint PPT Presentation

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Page 1: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

Gary LagerloefAquarius Principal Investigator

NOAA/CPO Climate Observation Division 6th Annual System Review

3-5 September 2008Silver Spring, MD

Page 2: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 23-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Oceanography, Vol. 21, No. 1

AQUARIUS/SAC-D Science Workshop

Puerto Madryn, Argentina,

3-6 December 2008

Page 3: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 33-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

• Aquarius Salinity Microwave Instrument

• Launch Vehicle

• Service Platform and SAC-D Science Instruments

• Mission Operations & Ground System

International Partnership between United States – Argentina

Aquarius/SAC-D Observatory

Page 4: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 43-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

3 beams 390 km wide swath.

76 x 94 km 96 x 156 km

84 x 120 km

Salinity Data

150km, Monthly, 0.2 (pss)

Salinity Data

150km, Monthly, 0.2 (pss)

Surface ValidationSurface Validation

Mission Design and Sampling Strategy

Beams point toward the night side to avoid sun glint

Beams point toward the night side to avoid sun glint

Launch 22 May 2010

Launch 22 May 2010

In Orbit Checkout

AquariusGround System

AquariusGround System

• Global Coverage in 7 Days• 4 Repeat Cycles per Month

• Global Coverage in 7 Days• 4 Repeat Cycles per Month

Sun-synchronous exact repeat orbit6pm ascending nodeAltitude 657 km

Page 5: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 53-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Basin scale spatial resolution provided by the Aquarius footprint:

•Top: Snapshot of a 1/8 degree OGCM SSS field.

•Middle: The same field with a 150 km Gaussian filter applied to simulate the Aquarius spatial resolution, removing much of the eddy scale structure while preserving good spatial resolution of basin and gyre scale structures.

•Bottom: Mean annual SSS from World Ocean Atlas 2005.

Page 6: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 63-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

SSS 30-day Retrieval Simulation

Representing both ascending and descending at Aquarius 3 horn footprints

30 day mean Input SSS field

30 day men Retrieved SSS

field

Page 7: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 73-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

SSS Retrieval Simulation Mean and Standard Deviation Errors

Representing both ascending and descending of all 3 horns

30 day SSS retrieval bias

30 day SSS retrieval error

standard deviation

Note degradation in high latitudes,

especially southern ocean

Page 8: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 83-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Breakdown of Simulated Retrieval Errors by Latitude Band

Individual 5.6 second sample standard deviation error

Mean bias error

Zonal mean SST

<0.15 psu

While these simulator results look very promising, we a certain to have overlooked something…

Frank Wentz and Sab Kim, Remote Sensing Systems; Aquarius Algorithm Development Team

Page 9: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 93-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

U.S. CLIVAR Salinity Working Group Proposed Control Volume Experiment

Constrain the complete surface atmosphere/ocean hydrologic [seasonal] cycle based on observations

Test and improve coupled climate models

Alternative regimes

•evaporative subtropical gyre

•high precipitation tropical regime Oceanography, Vol. 21, 2007

Page 10: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 103-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Potential Process Study in 2011

Discussion group meeting at WHOI 9-10 July 2008: Ray Schmitt, Eric Lindstrom, Steve Riser, Arnold Gordon, Bill Large, Jim Carton, Fred Bingham, Gary Lagerloef, Lisan Yu, David Fratantoni

Air-Sea Freshwater Budget Study

Location advantages:•Weak horizontal divergence•Low precipitation 1D physics•Modest eddy activity•Source of water for northern tropical thermocline•Stable SSS for satellite Cal-Val•Warm SST (better for Aquarius accuracy)•Leverages other resources: RAPID/MOC sections, Pirata Array, ESTOC time series (Canary Islands)•Logistically tractable

26 N

Page 11: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 113-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Circulation

Convergence Zone and Weak Advection

Page 12: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 123-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

North Atlantic Salinity Maximum

Wes

terl

ies

Trad

e win

ds

Florida Straits

Water vapor to the Pacific across central america

Wind stress curl

Arnold. Gordon

Science Questions:

What processes maintain the salinity maximum?

Where does the excess salt go?

What processes give rise to temporal variability?

What is the larger impact on the shallow overturning circulation?

Page 13: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 133-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Aquarius and Integrated In Situ Observations

GOSUD

Integrated Satellite + in situ

Salinity Observing System

Integrated Satellite + in situ

Salinity Observing System

Surface ValidationSurface Validation

Page 14: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 143-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

U.S. CLIVAR Salinity Working Group Recommendations - 2007

• In response to limitations of the historical observing system we support the maintenance and expansion of the current in situ observing system, especially Argo and the Volunteer Observing Ship thermosalinographs.

• We recommend enhancements to the global observing system specifically directed towards improved estimation of sea surface salinity:– Expand the Argo instrument suite to include Surface Argo

Salinity Measurements (Upper 5-m sensor) to allow a more precise calibration of Aquarius. (Skin depth ~2 cm)

– Support development and testing of sea surface salinity sensors for deployment on the surface drifters of the Global Drifter Program.

Page 15: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 153-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

TAO Array SSS

TAO Buoy 2S 165E

Delcroix & McPhaden, JGR 2002)

0.2 psu

Page 16: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 163-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Applying TSG Data for Understanding Calibration

Provided by Gary Lagerloef and John Gunn

The RMS difference between satellite and in situ data comprises several terms:

εO is an error due to the spatial

offset between the satellite and in situ samples (~0.2 psu; likely to be the largest term).

εP is the difference error between a

point salinity measurement and the area average over the instantaneous satellite footprint

(log-normal distribution, median ~0.05 psu, extremes ~0.5).

εZ is the difference error between

the skin depth (~1-2 cm) salinity and in situ instrument measurement generally at 0.5 m to 5

m depth (can be >1 psu in rain).

εC is the in situ sensor calibration

error, usually very small (<0.05 psu)

The RMS difference between satellite and in situ data comprises several terms:

εO is an error due to the spatial

offset between the satellite and in situ samples (~0.2 psu; likely to be the largest term).

εP is the difference error between a

point salinity measurement and the area average over the instantaneous satellite footprint

(log-normal distribution, median ~0.05 psu, extremes ~0.5).

εZ is the difference error between

the skin depth (~1-2 cm) salinity and in situ instrument measurement generally at 0.5 m to 5

m depth (can be >1 psu in rain).

εC is the in situ sensor calibration

error, usually very small (<0.05 psu)

Page 17: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 173-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Argo Enhanced SSS Float Trials

Purpose: To obtain “skin” salinity and upper 5m gradient statistics

• Argo CTD nominally shuts off at ~5m

• Steve Riser and Gary Lagerloef are assembling experimental Argo floats each with a secondary CTD sensor to profile to the surface. The primary CTD will shut off at ~5 m per normal operations.

• Sea-Bird developed a specialized “Surface Temperature Salinity” (STS) sensor which is programmed to profile the upper ~30 m and is inter-calibrated with the primary CTD

• We deployed the first at the HOT site near Hawaii late summer 2007. 

• Others are being deployed in the equatorial Pacific in 2008, including one in the warm pool.

• Development of at least 20 are being funded by NASA during the next 2 years.

Page 18: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 183-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Drifters SSS: COSMOS 2005 Field Test, Bay of Biscay

Reverdin et al., JTech, 2007

Apr Jun Aug-Sep Dec9-month

drifts <~0.06

SVP Drifters

Ready for more

extensive SSS trials

Parallel effort at WHOI

Page 19: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 193-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Priorities for Aquarius SSS Cal/Val and Ocean Process Studies

50-100 SSS Drifters in the N. Atlantic Subtropical gyre by 2011.

~50 Enhanced STS Argo in high rainfall and high evaporation regimes.

~50 SSS Drifters in the Southern Ocean (large satellite error)

Page 20: Aquarius/SAC-D Salinity Satellite Mission and the Ocean Observing System

NOAA Climate Review 203-5 September 2008, Silver spring MD

G. Lagerloef, et al.Aquarius and Ocean Observations

Salinity Satellite Mission

Aquarius/SAC-D Science Team Announcements

• A process is underway between NASA and CONAE to coordinate the selection process to form a joint mission science team to support both Aquarius salinity and the other SAC-D science instruments and objectives.

• US submissions are mainly through NASA ROSES, "Ocean Salinity Science Team" . Proposals are due in 18 March 2009; Notices of Intent due 16 January 2009.

• The next Aquarius/SAC-D science workshop is in Puerto Madryn Argentina, 3-5 December 2008. Abstract deadline 10 October 2008

• Fall AGU Special Session OS24: Climatic Variability in the Marine Freshwater Cycle; Abstracts due 10 September 2008