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. 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 approachwide-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.

A potential role of heat‐moisture couplings in the range expansion of Striga asiatica

“…We defined a heat‐moisture coupling event as an occurrence where the LST is ≥25°C and the RZSM percentile is ≥70. These cutoffs were chosen to ensure a temperature that allows for successful seed pre‐conditioning and germination (Aflakpui et al., 1998 ; Babiker et al., 2001 ; Matusova et al., 2004 ), as well as a soil‐moisture level in the approximate upper tercile, which is generally considered wet soil (Li et al., 2022 ; Tian & Zhang, 2023 ). Any instances with missing values were excluded during the cleaning process.…”

“…These cutoffs were chosen to ensure a temperature that allows for successful seed pre-conditioning and germination (Aflakpui et al, 1998;Babiker et al, 2001;Matusova et al, 2004), as well as a soil-moisture level in the approximate upper tercile, which is generally considered wet soil (Li et al, 2022;Tian & Zhang, 2023).…”

Evaluation of Several Satellite-Based Soil Moisture Products in the Continental US

“…Satellite-based soil moisture products could monitor drought and assess its evolution, which is essential to regions that lack stations [18]. Soil moisture could be converted into a drought index, which is used to classify and quantify the drought degree [19].…”