UNDERSTANDING PLANT WATER USE AND CARBON UPTAKE IS CRITICAL FOR ASSESSING ECOSYSTEM PRODUCTIVITY AGRICULTURAL PRODUCTION AND MANAGEMENT PRACTICES HYDROLOGIC CYCLE CARBON DYNAMICS AND FEEDBACKS TO THE CLIMATE SYSTEM. DIURNAL CYCLES OF EVAPOTRANSPIRATION (ET) WATER STRESS AND CARBON UPTAKE ARE OF SIGNIFICANT SCIENTIFIC IMPORTANCE FOR BETTER UNDERSTANDING PLANT WATER USE AND THE REGULATION OF WATER STRESS ON PLANT CARBON UPTAKE. SUB-DAILY (E.G. HOURLY) DATA OF ET WATER STRESS AND GPP ARE ESSENTIAL FOR UNDERSTANDING THE DIURNAL PATTERNS OF PLANT WATER USE AND CARBON UPTAKE. THE ECOSYSTEM SPACEBORNE THERMAL RADIOMETER EXPERIMENT ON SPACE STATION (ECOSTRESS) CAN TO SOME EXTENT CAPTURE THE TRAJECTORY OF THE DAILY ET CYCLING AS PLANTS OPEN AND CLOSE THEIR STOMATA OVER THE COURSE OF A DAY WITH ITS DIURNAL SAMPLING AND PROVIDES A GREAT OPPORTUNITY TO ASSESS DIURNAL CYCLES OF PLANT WATER USE. THE OVERARCHING GOAL OF THE PROPOSED PROJECT IS TO UNDERSTAND THE DIURNAL CYCLES OF PLANT WATER USE AND CARBON UPTAKE USING EXISTING AND NEW DATA PRODUCTS BASED ON ECOSTRESS MODIS AND FLUXNET.