KY EPSCoR: FY21: NASA: RID Project: Assessing the Impacts of Physiological and Environmental controls on the Accuracy of WUE: Linking Field Observations, Satellite Imagery, and Land Surface Model - Match for 3200002377

Planet Earth has experienced rapid changes in climate in the past decades and is likely to undergo further changes in the coming years. Much concern has been raised regarding the extent to which such perturbation affects terrestrial ecosystem processes and the services they provide. Water use efficiency (WUE, the ratio of carbon assimilation to water loss) is a key physiological parameter linking carbon and water cycles. Understanding changes in WUE is thus critical to quantify the terrestrial ecosystem response to rising atmospheric CO2 concentration. In this study, we will evaluate and assess the impacts of evapotranspiration (ET) and gross primary production (GPP) on ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) WUE product using observed data from two eddy covariance (EC) flux towers in Kentucky. This work will provide validation for ECOSTRESS WUE and quantify the impacts of Moderate Resolution Imaging Spectroradiometer (MODIS) GPP error on the overall accuracy of ECOSTRESS WUE. Also, we will use the relationship between observed and satellite data to improve and calibrate a land surface model ET and WUE estimates. Insights gained from this study will highlight the ability of ECOSTRESS to detect daily and seasonal changes in vegetation WUE, which will be important in understanding the soil-vegetation-atmosphere interactions in a changing climate.