The Aquarius/SAC-D Satellite Mission

1. The Aquarius/SAC-D Satellite Mission South Atlantic Workshop Buenos Aires 7-10 May 2007 Gary Lagerloef Aquarius Principal Investigator F. Raúl Colomb SAC-D Principal Investigator

2. Mission Partnership International Partnership between United States – Argentina • Service Platform and SAC-D Science Instruments • Mission Operations & Ground System • Aquarius Salinity Microwave Instrument • Launch Vehicle

3. NASA’s Mission Objective A Critical Climate Parameter Missing from the Present Satellite Observing Network Aquarius will yield an unprecedented view of ocean’s role in climate and weather Investigate the links between the global water cycle, ocean circulation and climate Make global, space-based measurements of Sea Surface Salinity (SSS) with high accuracy Observe and model seasonal and year-to-year variations of SSS , and how these relate to changes in the water cycle and ocean circulation A Key to Studying the Global Hydrologic Cycle and Global Change Aquarius Mission is About Understanding the Interactions Between the Global Water Cycle, Ocean Circulation and Climate Through the Measurement of SSS

4. CONAE’s Mission Objective SAC-D Science Mission is About Conducting Local Measurements Over Argentina Understanding ocean circulation, global water cycle and climate interaction Monitoring environmental changes, natural hazards and sea ice Monitoring atmospheric parameters Studying effect of cosmic radiation on electronic devices and characteristics of space debris Validate technology for future CONAE missions The SAC-D Science Mission is About Conducting Local Measurements Over Argentina and Contributing to Global Investigations of the Atmosphere, the Oceans and the Effects of Human and Natural Processes on the Environment as Defined in the Strategic Plan of the Argentine National Space Program

5. Instruments + S/P  Observatory Aquarius/SAC-D Observatory Microwave Radiometer MWR Satélite de Aplicaciones Científicas-D Service Platform SAC-D S/P New InfraRed Sensor Technology NIRST Mass: 1675 Kg Power:1443 W Oper. Life: 5 yrs Aquarius (primary instrument) High Sensitivity Camera HSC Data Collection System CARMEN-1 (ICARE-NG & SODAD) Technology Demonstration Package Radio Occultation Sounder for the Atmosphere DCS TDP ROSA

6. Instrument Objectives Specifications Resolution Owner Aquarius Understanding ocean circulation, global water cycle and climate interaction. Soil Measures over Argentina Integrated L-band radiometers (1.413Ghz) and scatterometer (1.26Ghz) Three beams: 76 x 94, 84 x 120, 96 x 156 km NASA MWR Precipitation rate, winds peed, sea ice concentration, water vapour, clouds 23.8 and 36.5 GHz H and V pol. Bandwidth: 0.5 and 1 GHz Swath:380 km 54 km CONAE NIRST Hot spots events, sea surface temperature measurement 3.8, 10.85 and 11.85  Swath: 180 km Tilt: +/-30 deg. 350 meters CONAE HSC Urban lights, electric storms, Polar regions, snow cover 450-900 nm swath: greater than 700 km 200-300 meters CONAE DCS Data Collection System 401.55 Mhz uplink 2 contacts per day with 200 platforms CONAE ROSA Atmospheric properties GPS Occultation Techniques Horiz: 300 km Vert: 300 m ASI Carmen 1 ICARE and SODAD I: Effect of cosmic radiation on electronic devices S: distribution of microparticles and space debris I: three fully depleted Si and Si/Li detectors S: four SMOS sensors I: 256 channels S: Sensitivity 5 μmpart at 10 km/sec CNES TDP Position, velocity and time determination Inertial angular velocity GPS receiver Inertial reference unit 20 m, 1 m/sec, .2µsec ARW: 8* 10-3 deg/sqrt h CONAE Level 1 Science Objectives

7. Sensitivity vs Radiometer Frequency Tb=εT ε = f(S, T, Freq, Incidence) 1400-1427 MHzProtected Band Aquarius Instrument Primary Objective: • Understand Ocean Circulation; Global water cycle and climate interaction • Measure global SSS from space (0.2 psu rms on 150x150 km scale over ice free oceans, monthly) Instrument Description & Measurement Technique: • Sea surface brightness temperature measured by stable polarimetric radiometers operating at 1.413 GHz. Salinity is derived by measuring brightness temperature at L-Band • Coincident sea surface backscattering cross-section measured by stable polarimetric scatterometer operating at 1.26 GHz. Roughness is the largest correction and is measured with the integrated L-band Scatterometer • Uses Deployable offset parabolic monolithic 2.5m reflector with three feedhorns provides three beams in a push-broom configuration • Revisit: 7 day repeat cycle • Mass: 400 kg; Power: 450 W • Operational Life: 3 years Data Products: • Derived Geo-located SSS • Time spaced averaged SSS maps 3 Beams, 390 km swath, full coverage between adjacent orbit tracks. 76 x 94 km 96 x 156 km 84 x 120 km

8. MWR Instrument Primary Objective: • Microwave Radiometer (MWR) measure surface brightness temperature in the frequency range sensitive to geophysical parameters over the ocean to contribute to climate and hydrological forecasting for the La Plata basin, Patagonia and Antarctica • MWR data complements Aquarius SSS measurements by providing 8 overlapping beams Instrument Description & Measurement Technique: • Two continuously operating radiometers at 23.8 GHz (K band; V-pol) and at 36.5 GHz (Ka band, polarimetric H & V) over land and sea (with 8 feeds per frequency) • 390 km Swath width (coincident with Aquarius) • Resolution of 50 km (across-track) • Coverage: Global Wind Speed Precipitation

9. Land use Index Simple land index derived from SSMIS 22V, 37V, 37H. Low resolution. Courtesy F. Wentz

10. Science Measurement Perspective Sun-synchronous exact repeat orbit 6pm ascending node Altitude 657 km; 98 deg inclination Earth viewing & Nadir pointing instruments Global Coverage in 7 Days 4 Repeat Cycles per Month Beams point toward the night side to avoid sun glint Surface Validation Ground System & Data Processing Launch 2010 Data to Community

11. Orbit and Swath

12. Smoothing Effect of the Aquarius Footprint

13. 5 March 2007 Science Goal: Net Freshwater Budget • Examine mean salt (SSS) advection and divergence • Trial balance with E-P net surface freshwater forcing U·∇S ~ S(E-P)/H OSCAR = Geostrophic + Ekman @ 15m

14. 2005-2006 Argo mean SSS

15. H Net Freshwater Flux Precipitation (GPCP) & Evaporation (Lisan Yu, WHOI)

16. Net flux vs Salinity divergence S(E-P)/H psu · year-1 U·∇S psu · year-1

17. Meridional Zonal Total (E-P)/H Surface forcing minus advection • Preliminary findings: • Global SSS divergence patterns are of the same magnitude as E-P forcing, and thus SSS advection has a predominant role in the net surface freshwater budget. • Differences between SSS divergence and (E-P)/H are of similar magnitude and are partly the result of meridional offsets of the peak latitudes.

18. Education & Public Engagement Education and Public Outreach will increase awareness and understanding of how the earth functions as a system – and technology’s role in enabling development of the knowledge – through Informal and Formal Education and Professional Development activities. http://www.conae.gov.ar/elespacioyud/ambitoeduc.html http://aquarius.gsfc.nasa.gov/education.html

19. 2010 A Space Odyssey