Global Flash Drought Monitoring Using Surface Soil Moisture
Overview
Research
Identity
Additional Document Info
View All
Overview
abstract
AbstractAbrupt onset and swift intensification characterize flash droughts. Global surface soil moisture (RS) from NASA's Soil Moisture Active Passive (SMAP) satellite can facilitate a nearrealtime assessment of emerging flash droughts at a 36km footprint. However, a robust flash drought monitoring using RS must account for the (a) short observation record of SMAP, (b) nonlinear geophysical controls over RS dynamics, and (c) emergent meteorological drivers of flash droughts. We propose a new method for nearrealtime characterization of droughts using Soil Moisture Stress (SMS, drought stress) and Relative Rate of Drydown (RRD, drought stress intensification rate)developed using SMAP RS (March 2015May 2021), footprintscale seasonal soil water retention parameters and landatmospheric coupling strength. SMS and RRD are nonlinearly combined to develop Flash Drought Stress Index (FDSI) to characterize emerging flash droughts (FDSI0.71 for moderate to high RRD and SMS). Globally, FDSI shows a high correlation with concurrent meteorological anomalies. A mechanistic evaluation of flash droughts is presented for the Northern Great Plains, Central South Africa, and Eastern Australia using FDSI, SMS, and RRD. About 5.6% of the earth's landmass experienced flash droughts of varying intensity and duration during 20152021 (FDSI0.71 for >30 consecutive days), majorly in global drylands. FDSI shows high skill in forecasting vegetation health with a lead of 02weeks, with exceptions in irrigated croplands and mixed forests. With readily available parameters, low data latency, and no dependence on model simulations, we provide a robust tool for global nearrealtime flash drought monitoring using SMAP.
