THE CRUCIAL ROLES OF SEA SURFACE SALINITY (SSS) IN EARTH S CLIMATE SYSTEM AS AN INDICATOR OF GLOBAL WATER CYCLE CHANGE AND AN AGENT IN UPPER OCEAN MIXING/STABILITY OFTEN GOES UNSUNG. NASA S AQUARIUS AND SOIL MOISTURE ACTIVE PASSIVE (SMAP) SATELLITES ARGO ADVANCED COMPUTATIONAL MODELS AND FIELD CAMPAIGNS LIKE THE SALINITY PROCESSES IN THE UPPER OCEAN REGIONAL STUDY (SPURS-1) IN THE NORTH ATLANTIC AND SPURS-2 IN THE TROPICAL PACIFIC HAVE CHANGED THIS. IN RECENT DECADES HIGH-RAINFALL LOW-LATITUDE REGIONS HAVE FRESHENED WHILE DRY SUBTROPICAL ZONES SHOW INCREASED SSS. THIS SIGNALS AMPLIFICATION OF THE GLOBAL WATER CYCLE A SYMPTOM OF CLIMATE CHANGE. THE DYNAMICAL ROLE OF SSS IN AIR-SEA INTERACTIONS IS MORE COMPLEX. IT DEPENDS ON AND AFFECTS OCEAN HEAT CONTENT. HEAT AND SALT CONTROL SURFACE DENSITY AND SUBSURFACE STRATIFICATION WHICH CONSTRAIN THE SURFACE MIXED LAYER. THE LATTER INFLUENCES AIR-SEA FLUXES AND MOST OCEAN DYNAMICS. THERE IS SOME EVIDENCE THAT SSS VARIABILITY MAY EVEN INFLUENCE CLIMATE MODES SUCH AS THE EL NI O-SOUTHERN OSCILLATION (ENSO) AND NORTH ATLANTIC OSCILLATION (NAO) BUT MORE WORK IS NEEDED TO UNDERSTAND THESE INTERACTIONS UPPER OCEAN SALINITY BUDGETS HELP TO UNDERSTAND SSS VARIABILITY AND FEEDBACKS TO CLIMATE YET ANALOGOUS-BUT-METHODOLOGICALLYDIFFERENT STUDIES YIELD DIFFERENT RESULTS. ALL METHODS FOR ESTIMATING BUDGETS HAVE LIMITS AND TO OUR KNOWLEDGE NO COMPREHENSIVE STUDIES OF SOURCES OF SALINITY BUDGET ERROR HAVE BEEN DONE. WE WILL: 1) INVESTIGATE PROCESSES CONTROLLING SURFACE SALINITY PATTERNS AND VARIABILITY IN HIGH AND LOW SALINITY REGIMES. 2) EVALUATE SALINITY BUDGET SENSITIVITY TO DATASET OR MODEL CHOICE AND RELATED SOURCES OF ERROR SUCH AS SAMPLING / RESOLUTION THAT OBSCURES PROCESSES ON LARGE OR SMALL SPATIAL SCALES. 3) INVESTIGATE DYNAMICAL IMPACTS OF UPPER OCEAN SALINITY ON AIR-SEA INTERACTIONS THAT CHARACTERIZE IMPORTANT WEATHER AND CLIMATE PHENOMENA. WE WILL USE MULTIPLE NASA SUPPORTED SATELLITE IN SITU AND MODEL-BASED ASSIMILATION DATA PRODUCTS AND A VERY HIGH RESOLUTION GLOBAL MODEL TO STUDY SSS BUDGETS AND INVESTIGATE SOURCES OF BUDGET ERROR ON SUBMONTHLY INTRASEASONAL SEASONAL AND INTERANNUAL TIMESCALES IN THE (A) LOW SALINITY TROPICAL PACIFIC WHERE ENSO OCCURS AND SPURS-2 IS CONDUCTED; (B) HIGH SALINITY NORTH ATLANTIC WHERE THERE THE NAO OCCURS AND SPURS-1 TOOK PLACE. WE ALSO PROPOSE TO: 4) CREATE A TIME-EXTENDED HIGH-RESOLUTION GLOBAL SSS PRODUCT THAT IS MORE ACCURATE THAN THOSE CURRENTLY AVAILABLE BY BLENDING ALL AVAILABLE SATELLITE SSS DATA AND IN SITU OBSERVATIONS. THIS PRODUCT WILL COMBINE THE GLOBAL SPATIOTEMPORAL COVERAGE OF HIGH-RESOLUTION SATELLITE DATA AND THE ACCURACY OF IN SITU DATA AND COVER A LONGER TIME SPAN THAN IS CURRENTLY AVAILABLE FROM SSS SATELLITE DATASETS. IT WILL BE USED IN SUPPORT OF OBJECTIVES 1-3 AND MADE PUBLICLY AVAILABLE. TOPICS WE ADDRESS ARE ALSO AT THE HEART OF THE SPURS MISSIONS. WE WISH TO USE RESOURCES AT OUR TEAM S DISPOSAL EXPERTISE WITH SSS SATELLITE DATA ANALYSIS OF BUDGETS FROM STATE ESTIMATES AND MODELS AND ANALYSIS OF UPPER OCEAN CURRENTS TO PROVIDE COMPLEMENTARY ANALYSES AND BUDGET ERROR ESTIMATES OVER THE GEOGRAPHICAL REGIONS ENCOMPASSING THE SPURS SITES. OUR SPATIOTEMPORAL SCALES OF EMPHASIS OVERLAP WITH BUT ARE NOT IDENTICAL TO THOSE OF SPURS YET ARE COMPATIBLE WITH SPURS AND US CLIVAR INTEREST IN UNDERSTANDING THE OCEAN RESPONSE TO FRESHWATER FORCING DUE TO CLIMATE AND THE NATURE OF THE CASCADE OF SALINITY VARIANCE ON ALL SCALES. THIS WORK HAS CRUCIAL RAMIFICATIONS FOR UNDERSTANDING GLOBAL SSS PATTERNS THEIR ROLES IN THE GLOBAL WATER CYCLE AND CLIMATE DYNAMICS AND THUS FOR IMPROVING PREDICTION CAPABILITIES.