aquarius/sac-d salinity satellite mission and the ocean observing system gary lagerloef aquarius...
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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
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
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
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
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.
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
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
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
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
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
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
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?
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
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.
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
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)
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.
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
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)
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