IN EASTERN BOUNDARY CURRENT SYSTEMS (EBCS) SEA SURFACE TEMPERATURE (SST) FRONTS ARE IMPORTANT FOR CIRCULATION DYNAMICS AND PROMOTING BIOLOGICAL ACTIVITY. PREVAILING EQUATORWARD WINDS DURING THE SUMMER RESULT IN OFFSHORE EKMAN TRANSPORT AND UPWELLING ALONG THE COAST WHERE SST FRONTS OFTEN FORM BETWEEN THE COLD UPWELLED WATER AND THE WARM OFFSHORE WATERS. LARGE-SCALE WIND PATTERNS UPWELLING AND SST ANOMALIES AND FRONTS IN EBCS VARY SPATIALLY SEASONALLY AND INTERANNUALLY. IN THE CALIFORNIA AND HUMBOLDT CURRENT SYSTEMS (CCS AND HCS RESPECTIVELY) INTERANNUAL VARIABILITY IN WIND PATTERNS COASTAL UPWELLING AND SST ANOMALIES HAVE BEEN LINKED TO THE EL NINO-SOUTHERN OSCILLATION (ENSO). DURING EL NINO DECREASES IN EQUATORWARD WINDS AND WARM TEMPERATURE ANOMALIES RESULTING FROM THE ADVECTION OF WARM WATER FROM THE EQUATOR OR BY DEEPENING OF THE THERMOCLINE DUE TO COASTAL KELVIN WAVES HAVE BEEN SHOWN TO FORCES CHANGES IN THE CCS AND IN THE HCS. THE ROLE THAT ENSO PLAYS IN SST FRONTAL VARIABILITY HOWEVER HAS NOT BEEN STUDIED. THIS PROJECT WILL EXTEND THE RESEARCH ON THE INFLUENCE OF ENSO ON OCEANIC AND ATMOSPHERIC CONDITIONS BY INVESTIGATING THE RESPONSE OF SST FRONTAL ACTIVITY TO EL NINO AND LA NINA IN THE CCS AND IN THE HCS. USING DAILY SATELLITE SST DATA SPANNING MULTIPLE DECADES SST FRONTS WILL BE DETECTED FROM SST GRADIENT MAPS USING AN EDGE-DETECTION ALGORITHM. THE SPATIAL AND TEMPORAL VARIABILITY OF SST FRONTS WILL BE COMPUTED AND COMPARED TO THE WIND AND SST ANOMALIES DURING NORMAL EL NINO AND LA NINA YEARS. POTENTIAL SPATIAL AND TEMPORAL LAGS BETWEEN THE ONSET OF ENSO EVENTS AND WIND FORCING SST ANOMALIES AND FRONTAL ACTIVITY WILL ALSO BE EXAMINED TO GAIN A MORE COMPLETE UNDERSTANDING OF THE OCEAN'S RESPONSE TO ENSO. SST FRONTAL ACTIVITY MAY ALSO BE INFLUENCED BY OTHER CLIMATIC EVENTS SUCH AS THE WARM "BLOB" THAT OCCURRED ALONG THE WEST COAST OF THE UNITED STATES FROM 2014 TO 2016. FURTHER ANALYSES USING OCEAN MODEL SIMULATIONS IN WHICH THE ENSO FORCING MECHANISMS ARE CONTROLLED IN EACH MODEL RUN WILL BE USED TO EXPLORE HOW THE FORCING MECHANISMS AND PROCESSES ASSOCIATED WITH EL NINO AND THE WARM "BLOB" IMPACT SST FRONTS IN THE CCS. THIS PROJECT WILL ADVANCE OUR UNDERSTANDING OF HOW PHYSICAL PROCESSES IN THE OCEAN ARE CONNECTED WITH CLIMATE VARIABILITY