Global Warming Induces Significant Changes in the Fraction of Stored Precipitation in the Surface Soil

The fraction of stored precipitation (FSP) in surface soil is a new metric to characterize the synoptic-scale dynamics of wet soil moisture anomaly, the impact of which on the atmosphere differs from that of dry anomaly. Investigating the response of FSP to global warming is essential for understanding the land-atmosphere coupling and hydroclimate predictability in a changing climate. Here we use the Coupled Model Intercomparison Project phase 6 (CMIP6) models to project future changes in global FSP under two shared socioeconomic pathway (SSP) scenarios. The historical simulation based on Community Land Model version 5 (CLM5) during 1951-2014 suggests that 14.4% of the global land precipitation is remained in the surface soil within 3 days. The CLM5 simulated FSP applies to validate CMIP6 historical simulations in terms of global mean, spatial correlation and variability, and 5 among 12 CMIP6 models are finally selected to estimate FSP changes in a warming future. Compared with the FSP during the end of 20th century, it increases (decreases) significantly over 29% (16%) of the global land areas after 100 years in the business-as-usual scenario (SSP245). Global warming will increase FSP significantly over Amazon, most of Europe, western USA and Tibet Plateau, while the FSP decreases significantly over India and West Africa due to the increase of precipitation and soil moisture. The changes are more significant in the non-mitigation scenario (SSP585). The projected changes in FSP imply changes in regional flood risk and predictability in a warming future.