Variations in Summer Extreme Heat Events in the Mongolian Plateau: Role of the Soil Moisture over the Inner Tibetan Plateau

Recent studies suggest that rapid warming over the Mongolian Plateau (MP) may intensify extreme heat events (EHEs). However, the characteristics and mechanisms driving summer EHEs over the MP (MP-EHEs) remain unclear. This study explores the interannual variations in summer MP-EHEs and their relationship with the summer soil moisture over the inner Tibetan Plateau (TP-SM). Results reveal that changes in the MP-EHEs are linked to a local high-pressure system over the MP region, inducing descending motion. Descending motion further results in decreased middle to low level cloud cover and increased shortwave radiation, thereby warming the surface, and triggering summer MP-EHEs. Further analysis indicates that increased TP-SM releases more latent heat flux, triggering local secondary circulation that reinforces the local high-pressure system over the MP region, promoting the occurrence of summer MP-EHEs. Additionally, model results from LBM and CMIP6 further confirm that variations in summer TP-SM contribute to the occurrence of the MP-EHEs.