Agricultural monitoring from the International Space Station: linking ECOSTRESS at different overpass times to actual field conditions

Driven by climate change, agroecosystems are expected to be facing more weather extremes including for many, exacerbated water scarcity in the coming years. In this context, monitoring crop-water stress through time and space is critical. The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) was launched in 2018 to capture heterogeneous patterns in crop-water dynamics with an unprecedented spatial, temporal, and spectral resolution. Previously, we showed that the Evaporative Stress Index (ESI) from ECOSTRESS varied substantially across the different times of day when observations were made (i.e., overpass time). Going beyond these findings, we further assessed the accuracy of the contrasting snapshots in ECOSTRESS ESI at the different overpass times. To that end, we decomposed the signal from ECOSTRESS and explored the link between ESI and other potential drivers. Our approach leveraged available crop mapping information from the global WorldCereal dataset and employed a multivariate linear regression model, which controlled for covariance and spatial autocorrelation. This analysis showed if (and when) ECOSTRESS best captured actual field conditions of crop health (or suboptimal productivity). Ultimately, our work provided new insights into the diurnal sampling provided by ECOSTRESS, its significance and limitations for future thermal infrared sensors in support of agricultural monitoring. This work was made possible by a fellowship from the National Academies of Sciences, Engineering, and Medicine (NASEM) U.S. National Committee for IIASA, with funds from the National Science Foundation (NSF Award OISE 1663864).