Combining Altimeter-derived Currents With Aquarius Salinity To Study The Marine Freshwater Budget Gary Lagerloef Aquarius Principal Investigator Yi Chao (JPL) Project Scientist Fabrice Bonjean (ESR) John Gunn (ESR) Jonathan Lilly (ESR) OSTST Meeting March 2007 Hobart, Tasmania F. Ral Colomb SAC-D Principal Investigator OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Science and Measurement Objectives Aquarius space-based measurements will provide systematic global sampling. Aquarius global coverage Aquarius global coverage Global Sea Surface Salinity (SSS) Maps 150 km Spatial Resolution 0.2 psu Monthly Accuracy Three Year Baseline Mission Global Sea Surface Salinity (SSS) Maps 150 km Spatial Resolution 0.2 psu Monthly Accuracy Three Year Baseline Mission How are global precipitation, evaporation, and the cycling of water changing? How can climate variations induce changes in the global ocean circulation? How are global precipitation, evaporation, and the cycling of water changing? How can climate variations induce changes in the global ocean circulation? Big Questions Sparse in situ ship and buoy observations OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping 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 Mission Partnership OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission 390 km wide swath. 76 x 94 km96 x 156 km 84 x 120 km 3 beams Salinity Data Surface 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 2009 In Orbit Chec kout Aquarius Ground System Aquarius Ground 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 orbit 6pm ascending node Altitude 657 km OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Single Day Orbit Swath Pattern The orbit precesses to yield complete coverage in 7 days OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Aquarius Sampling in Labrador Sea OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Smoothing Effect of the Aquarius Footprint OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission 5 March 2007 The Purpose of this Talk To examine mean salt (SSS) advection and divergence Contrast with SST advection and divergence Trial balance with E-P net surface freshwater forcing US ~ S(E-P)/H OSCAR = Geostrophic + 15m OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission mean U,V components OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Argo mean SSS OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Argo mean SST OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Salinity and Temperature Divergences US psu year -1 UT C year -1 OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Pacific Zonal Averages Zonal SST advection dominates in the equatorial zone whereas meridional dominates in in mid latitudes Meridional SSS advection dominates in all latitudes Meridional Zonal Total (E-P)/H Meridional Zonal Total OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Net Freshwater Flux Precipitation (GPCP) & Evaporation (Lisan Yu, WHOI) H OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Net flux vs Salinity divergence S(E-P)/H psu year -1 US psu year -1 OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Surface forcing minus advection Latitudes of peak SSS divergence are shifted merdionally relative to peak E-P, causing zonal difference patterns. Meridional Zonal Total (E-P)/H OSTST Workshop March 2007, Hobart Tasmania G. Lagerloef, et al. Multi-Satellite & Operational Applications Salinity Mapping Satellite Mission Preliminary Conclusions Contrasts of heat and salt divergences in the equatorial Pacific: Meridional advection dominates SSS divergence Zonal advection dominates SST divergence Meridional advection dominates both heat and salt in mid-high latitudes 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 to each of these terms, and are partly the result of meridional offsets of the peak latitudes.