Comparative assessment of gridded soil moisture data products (2000–2019) for drought detection: A study over Indian region

The soil moisture drought is an intermediate event between meteorological and agricultural droughts. The information on soil moisture droughts provides an indication about the resilience of the agricultural systems. In the present study, a comparative assessment of the monthly soil moisture gridded data products of Modern Era Retrospective analysis for Research and Applications, i.e., MERRA-2 (0.5° × 0.5°), Climate Prediction Center, i.e., CPC (0.5° × 0.5°), Global Land Data Assimilation System, i.e., GLDAS (0.25° × 0.25°), and European Space Agency Climate Change Initiative, i.e., ESA CCI (0.25° × 0.25°) during 2000 to 2019 was carried out in terms of drought occurrence and severity. The long-term soil moisture information was transformed into standardized soil moisture index (SSMI) using nonparametric distribution, followed by computation of drought duration and magnitude using thresholding approach. The long-term trends of drought parameters, i.e., duration and magnitude, were extracted using Mann–Kendall test and Sen’s Slope method, respectively. It was interesting to note that irrespective of zones, the SSMI derived from MERRA-2 and CPC have maximum coherence in terms of both pattern and intensity, followed by GLDAS. The trends of drought duration and magnitude differ based on the data products; however, frequent droughts were observed over parts of peninsular India and Indo-Gangetic plains irrespective of data products. The increased drought duration and magnitude were found over major parts of central and peninsular India, western parts of north-eastern India and eastern parts of north-western India.