Drought Monitoring and Evaluation by ESA CCI Soil Moisture Products Over the Yellow River Basin

The multisatellite-retrieved soil moisture (SM) products released by the Europe Space Agency's Climate Change Initiative (ESA CCI) program have been widely used in numerous fields, including drought monitoring. In this article, a cumulative distribution function is applied to match the simulated SM from the Variable Infiltration Capacity (VIC) model and fill in the missing records of ESA CCI SM. The weekly standard SM index (SSI) calculated from the ESA CCI SM dataset is utilized to monitor the agricultural drought over the Yellow River Basin (YRB) during 2000–2012. The performance of the ESA CCI SSI is compared with the Standard Precipitation Index (SPI), the Standard Precipitation Evapotranspiration Index (SPEI), the self-calibrating Palmer Drought Severity Index based on VIC model (VIC-scPDSI) and the anomalies of ESA CCI SM and Normalized Difference Vegetation Index (NDVI). The results show that the interpolated ESA CCI SM is significantly (p < 0.05) correlated with the observed SM, and more than 84% of the grids in the YRB display strong correlations with the global reanalysis SM. ESA CCI SSI presents a similar spatiotemporal pattern as VIC-scPDSI, while exhibiting a significantly delayed response to SPI and SPEI. The average residence time of drought reflected by ESA CCI SSI from short periods of extreme drought and long periods of less extreme drought are above 1 week and 3 weeks later than that represented by SPI and SPEI. Severe and extreme drought areas detected by ESA CCI SSI are generally larger than that captured by SPI, SPEI, and VIC-scPDSI.