Long-term climatological SM2RAIN dataset for drought monitoring

Drought is a natural disaster that has serious economic, social and environmental impacts. Drought monitoring is one of the components of drought risk management. The main requirement of drought monitoring is to have a reliable and accurate long-term rainfall dataset. SM2RAIN datasets are among the available rainfall products that estimate rainfall from satellite soil moisture observations. The high performance of SM2RAIN products has been shown in several studies over different regions of the globe. The aims here are as follow: 1) to develop the long-term climatological SM2RAIN datasets that cover the period of 1998-2020 at 0.25° spatial and monthly temporal resolution on the global scale. This dataset is designed by merging two rainfall SM2RAIN products including SM2RAIN-CCI (1998-2015) and SM2RAIN-ASCAT (2007-2020). For this purpose, the quantile mapping method is applied to remove the bias between these two products and match the monthly values. In the QM method, a correction factor is calculated during the overlap period (2007-2015) as a reference period and then applied to for the entire study period, 2) to analyses of drought based on standardized precipitation index on the global scale. In addition, the analysis is compared with drought analysis of other ground observations and reanalysis rainfall products such as the Global Precipitation Climatology Project (GPCP) and ERA5. The results show that the developed SM2RAIN-based rainfall product has the potential to improve global drought monitoring by capturing the drought events accurately.