CALIFORNIA EXPERIENCES HIGH SPATIAL-TEMPORAL VARIABILITY IN EVAPORATION. SPATIAL VARIATIONS ARE ASSOCIATED WITH THE NORTH-SOUTH GRADIENTS IN RAIN FALL THAT AFFECT THE TYPE OF NATIVE VEGETATION ITS LEAF AREA INDEX HOW ROOTS TAP GROUND WATER AND ITS PHYSIOLOGICAL RESPONSE TO SEASONAL DROUGHT. TEMPORALLY EVAPORATION OF NATIVE VEGETATION EXPERIENCES STRONG SEASONAL DYNAMICS IN EVAPORATION DUE TO THE WET COOL WINTERS AND THE HOT DRY SUMMERS. ACCURATE EVAPORATION PRODUCTS DERIVED FROM ECOSTRESS MUST CONSIDER SPATIAL AND SEASONAL CHANGES IN METEOROLOGY AND PLANT STRUCTURE AND FUNCTION. CONSEQUENTLY CALIFORNIA IS AN IDEAL YET CHALLENGING TEST CASE FOR APPLYING ECOSTRESS PRODUCTS. IN SHORT IF ECOSTRESS PRODUCTS WORK WELL ACROSS CALIFORNIA WE HAVE CONFIDENCE THEY WILL WORK WELL ACROSS MOST OTHER PORTIONS OF THE UNITED STATES. WE PROPOSE A PROJECT THAT WILL INVOLVE OPERATING A NETWORK OF AMERIFLUX SITES ACROSS AGRICULTURAL AND NATIVE VEGETATION OF CENTRAL CALIFORNIA THESE SITES INCLUDE AN OAK SAVANNA ANNUAL GRASSLAND CORN ALFALFA PASTURE AND RESTORED WETLANDS. AT THESE SITES WE WILL MAKE EDDY COVARIANCE MEASUREMENTS OF CARBON WATER AND ENERGY FLUXES MEASURE SITE CHARACTERISTIC METEOROLOGY AND SOIL CONDITIONS. WE WILL USE THESE DIRECT MEASUREMENTS OF EVAPORATION CARBON DIOXIDE FLUXES AND ENERGY EXCHANGE TO VALIDATE AND PARAMETERIZE ECOSTRESS PRODUCTS. WE WILL EVALUATE THE PERFORMANCE OF ECOSTRESS PRODUCTS WITH THE BIOPHYSICAL CANVEG AND BREATHING EARTH SYSTEM SIMULATOR (BESS) MODELS THESE MODELS COUPLE ENERGY BALANCE PHOTOSYNTHESIS AND STOMATAL CONDUCTANCE ALGORITHMS THAT ARE EVALUATED FOR THE SUN AND SHADE FRACTIONS OF THE CANOPY AND OPERATES WITH INPUTS FROM SATELLITE REMOTE SENSING INCLUDING MANY PRODUCTS FROM MODIS.