FUNDAMENTAL QUESTIONS REMAIN ABOUT THE MAINTENANCE AND PROPAGATION MECHANISMS FOR ORGANIZED CONVECTION IN THE TROPICS ON A VARIETY OF SCALES. THE PROPOSED WORK WILL CONTINUE OUR INVESTIGATIONS USING CYGNSS DATA INTO THE COUPLING BETWEEN WIND-DRIVEN SURFACE FLUXES AND TROPICAL CONVECTION. CYGNSS WIND SPEED AND SURFACE LATENT HEAT FLUX (LHF) OBSERVATIONS AND MODEL SENSITIVITY TESTS WILL BE USED TO INVESTIGATE THE IMPORTANCE OF LHF VARIABILITY FOR CONVECTION ON TIME AND SPACE SCALES RANGING FROM THE DIURNAL CYCLE AND MESOSCALE THROUGH INTRASEASONAL (IS). WE HYPOTHESIZE THAT WIND INDUCED LHF ARE AN IMPORTANT MAINTENANCE MECHANISM FOR CONVECTION ON THESE VARIOUS SCALES. IN PARTICULAR WE WILL: 1) USE CYGNSS WIND SPEED AND ASSOCIATED LHF RETRIEVALS COINCIDENT IMERG PRECIPITATION (P) ESTIMATES AND REANALYSIS FIELDS TO ASSESS THE IMPORTANCE OF LHF FOR MAINTAINING THE MJO AND SLOWING ITS PROPAGATION EXPANDING OUR PREVIOUS ANALYSIS WITH IMPROVED CYGNSS RETRIEVALS AND A LONGER DATA RECORD TO PROVIDE IMPROVED ACCURACY AND ROBUSTNESS. A PARTICULAR EMPHASIS WILL BE THE IMPORTANCE OF LHF FOR MAINTAINING MJO CONVECTION IN THE TIMOR AND ARAFURA SEAS THAT SUPPORTS EVENTS PROPAGATING THROUGH THE MC. WE HYPOTHESIZE THAT WIND-INDUCED FLUXES ARE AN IMPORTANT MAINTENANCE MECHANISM FOR THE MJO DURING BOREAL WINTER IN THE INDO-PACIFIC WARM POOL. 2) USE CYGNSS FIELDS AND COINCIDENT IMERG P TO ASSESS THE IMPORTANCE OF WIND INDUCED LHF FOR SUPPORTING BOREAL SUMMER IS CONVECTION IN THE EAST PACIFIC WARM POOL WHERE THE MJO IMPACTS EASTERLY WAVE (EW) AND TROPICAL CYCLONE (TC) ACTIVITY. GIVEN THE SHALLOWER CONVECTIVE DEPTHS IN THIS REGION LHF MAY BE COMPARABLY IMPORTANT TO RADIATIVE FLUX ANOMALIES FOR MAINTAINING IS CONVECTION THROUGH THE MOIST STATIC ENERGY BUDGET. GLOBAL (SP-CESM) AND REGIONAL (WRF) MODELING EXPERIMENTS IN WHICH IS LHF VARIABILITY IS DENIED WILL ASSESS ITS IMPORTANCE FOR IS CONVECTION. WE HYPOTHESIZE THAT WIND-INDUCED FLUXES ARE AN IMPORTANT MAINTENANCE MECHANISM FOR IS CONVECTION DURING BOREAL SUMMER IN EAST PACIFIC WARM POOL AND THAT DENYING IS LHF VARIABILITY IN MODELS PRODUCES MUCH WEAKER IS VARIABILITY. 3) ASSESS THE IMPORTANCE OF CYGNSS WIND SPEED AND LHF FOR SUPPORTING DIURNAL MESOSCALE CONVECTIVE EVENTS IN THE BIGHT OF PANAMA REGION THAT HAVE BEEN SHOWN TO PROPAGATE WESTWARD AND GROW UPSCALE INTO EWS AND SEED TC FORMATION. THE PERIOD OF THE OTREC FIELD CAMPAIGN DURING SUMMER AND FALL OF 2019 WILL BE A PARTICULAR FOCUS. FLUX DENIAL EXPERIMENTS WITH A REGIONAL CLOUD SYSTEM RESOLVING VERSION OF WRF WILL ASSESS THE IMPORTANCE OF FLUXES FOR SUPPORTING DIURNAL CONVECTIVE EVENTS AND SUBSEQUENT EW AND TC GROWTH. WE HYPOTHESIZE THAT EAST PACIFIC EW AND TC ACTIVITY IS SUPPRESSED WHEN LACK OF LHF SUPPORT WEAKENS DIURNAL CONVECTIVE SYSTEMS THAT PROPAGATE WESTWARD OUT OF THE PANAMA BIGHT. 4) USE CYGNSS OBSERVATIONS AND MODEL SENSITIVITY TESTS TO ASSESS THE IMPORTANCE OF WIND-DRIVEN FLUX VARIABILITY FOR SUPPORTING WEST PACIFIC MONSOON WIND BURSTS. DURING THE PISTON FIELD PROGRAM IN SUMMER OF 2018 PERSISTENT PERIODS OF STRONG WEST PACIFIC WESTERLY WIND ANOMALIES ENHANCED LHF AND ENHANCED P WITH TIMESCALES OF 10-20 DAYS WERE OBSERVED. WE HYPOTHESIZE THAT FEEDBACKS BETWEEN ENHANCED MONSOON WESTERLY FLOW SURFACE LHF AND P HELP TO MAINTAIN MONSOON WESTERLY WIND EVENTS ON 10-20-DAY TIMESCALES OVER THE WESTERN NORTH PACIFIC. THIS PROPOSAL ADDRESSES THE COUPLING AND FEEDBACK MECHANISMS BETWEEN WIND-DRIVEN SURFACE FLUXES AND TROPICAL CONVECTION IN GENERAL AND MESOSCALE CONVECTIVE SYSTEMS IN PARTICULAR AS STATED IN THE CYGNSS CALL. THE PIS HAVE EXTENSIVE EXPERIENCE IN THE OBSERVATIONAL ANALYSIS THEORETICAL UNDERSTANDING AND MODELING OF CONVECTION-FLUX COUPLING ON IS AND SHORTER TIMESCALES IN THE TROPICS INCLUDING AS PART OF THE CYGNSS SCIENCE TEAM. THE PROPOSED WORK WILL FUND SEVERAL MONTHS OF DR. EMILY RILEY DELLARIPA S SALARY SUPPORT FOR A GRADUATE STUDENT AND SUMMER SALARY SUPPORT FOR DR. ERIC MALONEY.