Can multiscalar meteorological drought indices detect soil moisture droughts? A study of Indian regions

Abstract

The present study aims to explore the potential of multiscalar meteorological drought indices in detecting soil moisture drought events. The standardized soil moisture index (SSMI), standardized precipitation index (SPI), standardized evapotranspiration index (SEI), standardized precipitation evapotranspiration index (SPEI) and multivariate moisture anomaly index (MMAI) were computed using long-term (1980–2015) MERRA-2 soil moisture, precipitation and/or evapotranspiration data products. The performances of the meteorological indices were evaluated based on a zone-wise and spatial correlation approach along with failure rate (FR) and false alarm rate (FAR) values. The spatial correlation was highest in SEI, followed by MMAI, in comparison to SPI and SPEI. FR and FAR values indicated that SEI is the best index for detecting soil moisture drought events, whereas MMAI outperformed the other indices in representing combined drought events, i.e. meteorological or/and soil moisture droughts. The outcome of the study may be useful in retrieving information about soil moisture drought over a region using only meteorological parameters.