UNDERSTANDING THE INFLUENCE OF LARGE GRADIENTS IN THE EXTRATROPICAL SEA-SURFACE TEMPERATURE FIELD ON THE TROPOSPHERIC CIRCULATION.UNTIL THE PAST DECADE THE PREVAILING VIEW OF EXTRATROPICAL ATMOSPHERE/OCEAN INTERACTION WAS THAT - TO FIRST ORDER - THE SURFACE WIND FIELD DRIVES LARGE-SCALE VARIABILITY IN THE SEA-SURFACE TEMPERATURE (SST) FIELD AND THAT THE FEEDBACKS FROM THE SST FIELD TO THE ATMOSPHERE ARE RELATIVELY WEAK. BUT OUR UNDERSTANDING OF EXTRATROPICAL ATMOSPHERE/OCEAN INTERACTION CHANGED DRAMATICALLY WITHTHE ADVENT OF HIGH SPATIAL RESOLUTION REMOTELY SENSED DATA WHICH IS CAPABLE OF RESOLVING LARGE HORIZONTAL GRADIENTS IN THE SST FIELD. ANALYSES BASED ON SUCH DATA HAVE REVEALED THAT ON SMALL SPATIAL SCALES THE SURFACE WIND FIELD DOES NOT DRIVE BUT RATHER IS DRIVEN BY THE SST FIELD. NUMERICAL AND OBSERVATIONAL ANALYSES REVEAL THAT OVER SELECT REGIONS OF THE GLOBE LARGE GRADIENTS IN THE SST FIELD HAVE A MARKED SIGNATURE IN THE FREE TROPOSPHERIC CIRCULATIONVIA CHANGES IN VERTICAL MOTION INDUCED WITHIN THE ATMOSPHERIC BOUNDARY LAYER. PREVIOUS STUDIES HAVE FOCUSED PRIMARILY ON THE IMPLICATIONS OF LARGE GRADIENTS IN THE SST FIELD FOR THE MEAN CLIMATE. THE PROPOSED WORK WILL EXAMINE PRIMARILY THE IMPLICATIONS OF LARGE GRADIENTS IN THE SST FIELD FOR CLIMATE VARIABILITY. IT WILL EXAMINE HOW WHY AND TO WHAT EXTENT LARGE GRADIENTS IN THE SST FIELD INFLUENCE THE LARGE-SCALE ATMOSPHERIC CIRCULATION ACROSS A RANGE OF SPATIAL AND TEMPORAL SCALES. AND IT WILL EXPLOIT A RANGE OF NUMERICAL MODELS AND OBSERVATIONAL ANALYSES WITH HIGH-SPATIAL RESOLUTION SST DATA TO DO SO. THE WORK WILL BRING TO THE NASA PHYSICAL OCEANOGRAPHY PROGRAM A FOCUS ON THE LINKAGES BETWEEN DYNAMIC VARIABILITY IN THE UPPER OCEAN AND THE CLIMATE SYSTEM. THE STATED PRIMARY SCIENTIFIC GOAL OF THE NASA PHYSICAL OCEANOGRAPHY PROGRAM IS "TOWARD UNDERSTANDING THE OCEAN'S ROLE IN CLIMATE VARIABILITYAND ITS PREDICTION" AND ONE OF THE TWO STATED THEMES FOR THE CURRENT CALL IS THE "EXPLOITATION OF SEA-SURFACE TEMPERATURE PRODUCTS". THE PROPOSED RESEARCH SPECIFICALLY ADDRESSES BOTH THEMES. THE PROPOSED WORK WILL: 1) EXAMINE IN DETAIL THE LINKAGES BETWEEN FINESCALE FEATURES IN THE SST FIELD SURFACE WIND STRESS AND VERTICAL MOTION IN THE FREE TROPOSPHERE. THE WORK WILL PROVIDE INDEPENDENTSUPPORT FOR PREVIOUS STUDIES OVER THE GULF STREAM AND KUROSHIO BUT WILL EXTEND THOSE ANALYSES TO OTHER KEY REGIONS OF THE EXTRATROPICAL NORTHERN HEMISPHERE AND SOUTHERN HEMISPHERE. 2) EXAMINE THE LINKAGES BETWEEN VARIABILITY IN FINE-SCALE FEATURES IN THE SST FIELDAND THE FREE TROPOSPHERIC CIRCULATION OVER ALL MAJOR WESTERN BOUNDARY CURRENTS AND EXAMINE TO WHAT EXTENT FINE-SCALE VARIABILITY IN THE SST FIELD PROJECTS ONTO THE ATMOSPHERIC CIRCULATION OVER OTHER (AND LESS HEAVILY INVESTIGATED) REGIONS OF THE WORLD-OCEAN. 3)EXAMINE TO WHAT EXTENT LARGE GRADIENTS IN THE SST FIELD DETERMINED THE AMPLITUDE AND LOCATION OF THE ATMOSPHERIC STORM TRACKS. THISWILL BE EXAMINED IN THE CONTEXT OF THE LONG-TERM MEAN AND INTERANNUAL VARIABILITY IN LARGE LOCAL GRADIENTS IN THE SST FIELD. 4) EXAMINE THE INFLUENCE OF FINE-SCALE VARIABILITY IN THE SST FIELD ON ATMOSPHERIC CLOUDINESS AND PRECIPITATION. 5) DEVELOP AND RUN NUMERICAL EXPERIMENTS THAT TEST HYPOTHESES MOTIVATED BY THE OBSERVATIONAL ANALYSES. THE PIS HAVE EXTENSIVE EXPERIENCE IN THE ANALYSES AND DIAGNOSES OF ATMOSPHERE/OCEAN INTERACTION AND LARGE-SCALE TROPOSPHERIC DYNAMICS IN BOTH OBSERVATIONS AND NUMERICAL MODELS. THE PIS WILL BRING TO THE NASA PHYSICAL OCEANOGRAPHY PROGRAM EXPERTISE IN THE DYNAMICAL PROCESSES THAT LINK SST VARIABILITY TO LARGE SCALE TROPOSPHERIC CLIMATE. THE FUNDING REQUEST WILL BE FOR ~330 K/YEAR FOR THREE YEARS AND WILL PROVIDE SUPPORT FOR 1 POSTDOC 1 RESEARCH SCIENTIST 1 GRADUATE STUDENT AND 3 MONTHS OF PI SALARY.