Investigation of the Impacts of Drought Severity on Ecosystem Water-Use Efficiency and Drought Recovery across the Contiguous United States

Drought, as a prolonged period of moisture deficiency in land surface, affects terrestrial ecosystems from structural and functional perspectives, which leads to profound imbalances in the terrestrial carbon cycle. Ecosystem Water-Use Efficiency (WUE) plays an important role in carbon and water cycles, both of which are fundamental for ecosystem state, climate and the environment. Here, we present an assessment of the impacts of drought and its severity on WUE, Gross Primary Productivity (GPP), and Evapotranspiration (ET) across the Contiguous US (CONUS). GPP and ET datasets were retrieved from the moderate resolution imaging spectroradiometer (MODIS). Soil moisture simulations from land surface modeling are utilized to detect and characterize agricultural drought episodes. GPP as biome vitality indicator against drought stress, is used to investigate the ecosystems' required time to revert to pre-drought condition (drought recovery duration). Results show that WUE almost always tends to increase in response to severe (or worse) drought episodes while, ET is expected to decrease during severe (or worse) drought episodes. Lastly, a positive correlation is found between drought recovery duration, drought severity, and duration, meaning that a protracted drought recovery is more likely to happen following severe droughts with prolonged duration.