Satellite-Based Assessment of Meteorological and Agricultural Drought in Mainland Southeast Asia

Abstract

Satellite-based soil moisture products allow direct monitoring of agricultural drought, especially in regions with sparse ground-based observations. In this study, a soil moisture drought index only based on satellite soil moisture is developed and adopted to assess drought in Mainland Southeast Asia (MSA). We report here on an exceptionally severe Mainland Southeast Asia drought in 2016, which is believed to be strongly linked to the 2015-2016 super El Niño strongly. The event began in February 2016 and lasted until May 2016, with more than 50% of the study areas suffering from moderate drought or worse at peak period. We assess the evolution of agricultural droughts (defined as prolonged deficit in soil moisture) by placing it in the context of the forcing meteorological drought (prolonged deficit in precipitation). The drought assessment using satellite soil moisture is temporally consistent with precipitation-based metrics, but allows for better mapping of the spatial and temporal patterns of how a precipitation deficit may or may not lead to a soil moisture deficit. The specific advantages of a remote-sensing approach - wide-coverage without need for spatially-dense, ground-based climatological records, and sensitivity to otherwise unmeasured irrigation inputs - suggest further opportunity for drought monitoring in ungauged regions, particularly in agricultural contexts.