Assessing the impacts of flash drought on terrestrial ecosystem based on satellite data

Drought within a short time, termed flash drought (FD), severely affects terrestrial ecosystems and water resources. Water use efficiency (WUE) is an essential parameter in understanding the relationship between the water and carbon cycles. However, little is known about the response of WUE to FDs in the Korea peninsula. Therefore, this study identified FD events in Korea using the evapotranspiration (ET) based Standardized Evaporative Stress Index (SESI) and rate of intensification (RI) using soil moisture at flux tower site. Results showed that FD events detected similar patterns in both SESI and RI. At the regional scale, we identified Korea FD frequency and duration via anomalies in SESI using MODerate Resolution Imaging Spectroradiometer (MODIS). Results showed that Korea suffered from 61.3% of FD events for 20 years. The regions with the most FD events were primarily found within the north and east, where the main landcover type is forest, and long FD events (over 30 days) were detected in the northeastern study region. In addition, the effects of FD events on WUE were different based on FD magnitude and landcover types. The changes in WUE response to moderate FD events were obviously driven by the GPP, and the WUE in cropland was observed the highest sensitivity to FD magnitude. To analyze FD impacts on cropland in detail, we focus on monitoring the crop response to FD using microwave remote sensing data such as Synthetic Aperture Radar (SAR) which will be helpful to detect FD effects on crops in a higher resolution.