Aquarius Satellite Salinity Measurements. Simon Yueh Post Launch Cal/Val team Lead Jet Propulsion Laboratory California Institute of Technology

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1 Aquarius Satellite Salinity Measurements Simon Yueh Post Launch Cal/Val team Lead Jet Propulsion Laboratory California Institute of Technology Aquarius/SACD Science Team Meeting Buenos Aires April 11-13, 2012

2 A Team Effort Gary Lagerloef (ESR) Hsun-Ying Kao (ESR) David Carey (ESR) David LeVine (GSFC) Jeff Piepmeier (GSFC) Emmanuel Dinnat (GSFC) Paolo de Matthaeis (GSFC) Liang Hong (GSFC) Cuneyt Utku (GSFC) Chris Ruf (U Mich) David Chen (U Mich) Doug Vandemark (UNH) Linwood Jones (UCF) Yazan Hejazin (UCF) Simon Yueh (JPL) Shannon Brown (JPL) Sid Misra (JPL) Greg Neumann (JPL) Adam Freedman (JPL) Alex Fore (JPL) Wendy Tang (JPL) Xiaolan Xu (JPL) Rajat Bindlish (USDA) Peter Hacker (NASA HQ) Yi Chao (RS Solutions) Frank Wentz (RSS) Kyle Hilburn (RSS) Thomas Meissner (RSS) Joel Scott (RSS) And others 2

Assembly (1 of 3) Sunshade Boom Aquarius (Sea Surface Salinity) L-band

3 Aquarius Instrument Active-Passive L-Band Sensing Feed Horn (1 of 3) 2.5-m Dia Reflector Bipod (1 of 3) Primary Structure OMT/Radiomete r Front-End Assembly (1 of 3) Sunshade Boom Aquarius (Sea Surface Salinity) L-band radiometer and scatteroemter Push-broom (single look) <0.1 K for radiometer <0.1 db for scatterometer 3

4 Pointing and Time Tag Assessment Radiometric Cal Bias Removal RFI Current Schedule for Post Launch CAL/VAL Requirement: No later than twelve (12) months after the end of the IOC period, the Aquarius Project shall deliver the first release of data products (containing at least six (6) months of data) to a NASA Distributed Active Archive Center (DAAC). OOCO (IOC): Ends in November 2011 Cal/Val phase begins at the end of OOCO with a duration of 12 months Milestones and meetings: Cal/val meetings: November 2011, March 2012 April 2012 Aquarius/SACD science team meeting Rain Filtering Model Functions Reprocessing Error Assessment Asc/Des Bias Sept Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept 4

5 Temperature (Deg C) Temperature (Deg C) Excellent Thermal Control The Aquarius electronics has been under excellent thermal control since turn on with the temperatures of front end within +/- 0.1 deg C. Aquarius CND Temperatures Temperature CND 1 CND 2 CND 3 Primary Structure Feed Horn (1 of 3) 2.5-m Dia Reflector OMT/Radiome ter Front-End Assembly (1 of 3) Sunshade :00: :00: :00:00 OMT Probe Temperatures UTC Time :00: :00:00 Daily Average Bipod (1 of 3) Boo m Aquarius OMT Probe Temperature OMT 1H OMT 1V OMT 2H OMT 2V OMT 3H OMT 3V Daily Average :00: :00: :00:00 UTC Time :00: :00:00 5

% Radiometer Frequency Interference Mitigation Built-in high data sampling rate with short accumulation and software threshold adjustment allow effective removal of most RFI over open ocean.

6 % Radiometer Frequency Interference Mitigation Built-in high data sampling rate with short accumulation and software threshold adjustment allow effective removal of most RFI over open ocean. H Pol TA and TF Histogram from Aug. 25, 2011 to Feb. 25, 2012 with < 0.1% Land and Ice TA TF K 6 C. Ruf and D. Chen, U. Michigan

Sigma0 - Model (db) Scatterometer Calibration Scatterometer calibration stability has been within 0.1 db since turn on. The differences of measured and model Sigma0 have been within 0.

7 Sigma0 - Model (db) Scatterometer Calibration Scatterometer calibration stability has been within 0.1 db since turn on. The differences of measured and model Sigma0 have been within 0.1 db There is a small ascending and descending difference, which seems to be converging. Scat Sigma0 - Model GSFC V1.2.3 Ocean Only (NCEP) day avg VV asc Beam 1 7 day avg VV asc Beam 2 7 day avg VV asc Beam 3 7 day avg VV des Beam 1 7 day avg VV des Beam 2 7 day avg VV des Beam 3 Sigma0 indicates the wind velocity variation oceans (e.g., Beam 2 VV) :00: :00: :00:00 UTC Time :00: :00:00 7

0VV 0VVm ) ( 0HH 0HHm ) Fpol( SSS, W, ) 2 2 2 2 2 T 2 T ( k p 0VV ) ( k p 0HH ) Standard deviation of scat speed SSMI speed <

8 Aquarius Scatterometer Wind has excellent accuracy Minimize cost function in salinity (SSS), wind speed, direction given Aquarius radiometer and scatterometer data (Yueh and Chaubell, TGRS, April 2012) ( I I ) ( Q U Qm U ) m m ( 0VV 0VVm ) ( 0HH 0HHm ) Fpol( SSS, W, ) T 2 T ( k p 0VV ) ( k p 0HH ) Standard deviation of scat speed SSMI speed < 2 for all speeds less than 15 m/s Scat Wind Speed Map Scat Wind Errors vs. SSMI 2D log histogram 2D log histogram 2D log histogram 8

9 Radiometer Calibration Radiometer calibration has been meeting the requirement with under 0.13 K changes in 7 days. A slow secular calibration drift in all channels detected by two techniques developed by the cal/val team prior to launch: vicarious calibration technique and modeled-measured TB. Beam 1V Beam 2V Beam 3V Beam 1H Beam 2H Beam 3H 9

ND(A) = (Ant+ND)-(Ant) Reference + ND CND = (Ant+CND)-(Ant) Antenna + ND Deflection

10 Radiometer Calibration Counts and Ratios CND Five calibration states: ND Deflections Antenna only (globally avg d) ND(R) = (Ref+ND)-(Ref) Reference only (Dicke load) ND(A) = (Ant+ND)-(Ant) Reference + ND CND = (Ant+CND)-(Ant) Antenna + ND Deflection ratios Antenna + CND Unitless Piepmeier, Microrad 2012 Remove downstream systematics 10

11 Blue = ND(R)/CND Green = ND(A)/ND(R) Aquarius Radiometer Deflection Ratio Features Four features: 1. Monotonic component (~0.5% to 1%) 2. Small variations 3. Variations (0.0005) 4. Monotonic component ( to 0.001) V-pol H-pol Piepmeier, 2012 UTC Day 11

12 Radiometer Calibration Instrument-based Deflection Ratio technique is effective in removing the slow calibration drift (blue curves) the residual effect (red curves) is under 0.2 psu Root causes are being assessed to improve the calibration accuracy. May exercise the vicarious calibration technique to remove the residual drift Beam 1V Beam 2V Beam 3V Beam 1H Beam 2H Beam 3H Piepmeier,

13 Improving Accuracy Accuracy is rapidly improving since the start of mission Detailed assessment by Kao and Lagerloef on day Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov 1.3 V psu 0.9 V1.2 DR V Projection 13

14 Emerging New Products Features of Aquarius enable the development of several emerging new products most are going through calibration and validation Ocean Surface Wind (Yueh et al.) Soil Moisture (Jackson and Bindlish) September 2011 Land Surface Freeze/Thaw (Xu et al.) Faraday Rotation Angle (Ionospheric Electron Content) Polar sea ice fraction (Freedman) 14

15 Summary of Current Cal/Val Assessment Aquarius instrument has been performing exceptionally well On-orbit thermal control meets the design requirement (0.1 deg c stability) Scatterometer calibration has been very stable Small residual ascending and descending bias is being examined Radiometer calibration meets the calibration requirement (0.13K within 7 days). Vicarious calibration and instrument-based calibration techniques are available to correct the observed calibration drift Being also investigated is a small ascending-descending bias There will be many other new science products. Aquarius surface salinity accuracy has been rapidly improving although there are a few challenges ahead for cal/val. 15

Aquarius/SAC-D Mission Mission Simulators - Gary Lagerloef 6 th Science Meeting; Seattle, WA, USA July 2010

Aquarius/SAC-D Mission Mission Simulators - Gary Lagerloef 6 th Science Meeting; Seattle, WA, USA Mission Design and Sampling Strategy Sun-synchronous exact repeat orbit 6pm ascending node Altitude 657