Evaluation of the Effectiveness of Downscaled Precipitation Data in Drought Monitoring

Satellite-based precipitation products (SPPs) are considered ideal sources for drought monitoring. However, the coarse spatial resolution of SPPs constrains their utility in drought analysis at the regional scale. Spatial downscaling techniques can further increase the spatial resolution of SPPs, thereby facilitating the acquisition of more detailed drought information. Nevertheless, there is a lack of evaluation of the effectiveness of downscaled precipitation data in drought monitoring in existing research works. In this article, based on the case study in Northeast China, the 10-km monthly Integrated MultisatellitE Retrievals for global precipitation measurement (GPM IMERG) precipitation data were downscaled to 1 km. Then, the 1-km Standardized Precipitation Index (SPI) at multiple temporal scales (i.e., 1, 3, 6, and 12 months) was calculated based on the downscaled precipitation data. A comprehensive evaluation was conducted to assess the effectiveness of downscaled precipitation data in drought monitoring. The results indicated that the SPI calculated from 1-km downscaled results can reproduce more detailed spatial distribution patterns of meteorological drought compared to the SPI derived from the 10-km original GPM. The correlation coefficients between the 1-km SPI and that from station data are above 0.88 for validations at both spatial and temporal dimensions. Moreover, it was found that the SPI is more suitable for monitoring droughts from medium to long-term periods (e.g., seasonal to half-year scales).