Aquarius Sea Surface Salinity satellite mission validation using

Aquarius Sea Surface Salinity satellite mission validation using near real-time, in-situ oceanographic data John T. Gunn, AVDS Manager Earth & Space Research 1910 Fairview Ave. E. , Suite 210 Seattle, WA 98102 Ph: 206 -726 -0501; Email: gunn@esr. org 1 st Joint GOSUD/SAMOS Workshop Boulder, Colorado 2 -4 May, 2006

Salinity Satellite Mission International Partnership Mission • Aquarius Salinity Microwave Instrument • Service Platform and SAC-D Science Instruments • Launch Vehicle • Mission Operations & Ground System 2 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission Single Day Orbit Swath Pattern The orbit precesses to yield complete coverage in 7 days 3 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Mission Design and Sampling Strategy Salinity Satellite Mission Sun-synchronous exact repeat orbit 6 pm ascending node Altitude 657 km • Global Coverage in 7 Days • 4 Repeat Cycles per Month Beams point toward the night side to avoid sun glint In Orbit Check out Surface Validation 3 beams 390 km wide swath. 76 x 94 km 96 x 156 km Aquarius Ground System 84 x 120 km Launch March 2009 Salinity Data 4 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission The Aquarius Validation Data Segment (AVDS) will collect and process surface measurements for the Aquarius data processing • Liaison with observers • Daily data acquisition • Quality control/editing • Uniform data format AVDS Deliver surface calibration data to Aquarius and SMOS Data Processing Centers 5 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

AVDS In-situ Data Sources Salinity Satellite Mission Validation Data Sampling Parameters Platform Quantity Type Distribution Min Depth Latency Argo Buoys ~300/day Profile float Ocean-wide 5 m 1 day TAO/Triton 1 36 of 68 With salinity Mooring Tropical Pac 1 m 1 day PIRATA 15 Mooring Tropical Atl 1 m 1 day GDP buoys 2 Sfc Salinity 50 to 300 Surface drifter Ocean-wide 0. 5 m 2 mos Shipboard Thermosalinograph varies Hull-mounted Ocean-wide 5 m 2 days GTSPP varies CTD profile Ocean-wide 1 m TBD 1 Funding 2 Funding for additional sensors and 50 additional buoys planned for FY 07 for 50 buoys with near surface S sensors in FY 07 ramping up to 300 in FY 09 6 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission In-situ data GTSPP Via ftp daily AVDS ADPS ESR GSFC Va lid at ion da ta USERS 7 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission AVDS-ADPS Interaction AVDS provides: -Position (latitude, longitude) -Time -Acceptable deltas for position and time -Format is ASCII -Other identifying information (TBD) ADPS returns: All Aquarius data collected within position and time windows -Format is ASCII -Include brightness Temp (TB), derived salinity, position, time of Level 2 data (along track) -Other identifying information (TBD) 8 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

User Community Products Salinity Satellite Mission AVDS will provide the following to the surface salinity user community: • Tabular collection of in-situ and Aquarius SSS data for matched pairs • Description of statistical selection process by in-situ data type • Access to match-up criteria, in-situ data and edited, tabular coincident measurements via data servers, as shown below. AVDS In-situ data base Position, time Window for matchup Edited, tabulated Coincident meas. 9 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission • Exchange formats between AVDS and ADPS will use an established • system developed for the Sea. Wifs system The existing format structure will require only slight modifications to adapt to the Aquarius validation requirements 10 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission Surface Current Data validation ESR Satellite derived surface currents with validation using GDP buoys www. oscar. noaa. gov www. esr. org 11 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission • • • Desired Validation Database Attributes Searchable in time and space Reasonable level of Quality Control Format with comfortable ease-of-use Source Traceability and documentation (metadata) Internet access to data in near real-time (< 1 week delay) Two examples follow; GOSUD thermosalinograph underway data and ARGO profiling buoys data 12 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission • • • GOSUD Data Distribution 2006 Data is stored by year and ship 2006 data as of end of April 2006 Distribution somewhat constant in time (~5 -6 K point per week) Some outliers in position Cruise tracks repeated (limited mid-Pacific coverage) 13 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission • • ARGO Data Distribution Data is stored in daily files Two consecutive days in April Number of data points drops but distribution in time is similar Duplicate points exist for April 24 th data (can affect statistics) 14 of 15 GOSUD/SAMOS: John Gunn 4 May 2006

Salinity Satellite Mission Conclusions • Access and ease of use for global data bases are significantly • • • improved over the last few years Aquarius will require access to validation in near real-time mode. As such, initial QC is very important Idiosyncrasies of various validation data sets will require careful evaluation in their application to satellite fields Delayed mode data (high QC level) will be important for re-analysis efforts but are probably delayed too long for use in validating initial data distribution 15 of 15 GOSUD/SAMOS: John Gunn 4 May 2006