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

Recent studies have suggested 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). The results reveal that changes in the MP-EHEs are linked to descending atmospheric motion induced by a local high-pressure system over the MP region. Descending motion further results in decreased mid-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 results in a greater latent heat flux, triggering a local secondary circulation that reinforces the local high-pressure system over the MP region, thus serving to promote the occurrence of summer MP-EHEs. Additionally, model results from the linear baroclinic model (LBM) and CMIP6 further confirm that variations in summer TP-SM contribute to the occurrence of the MP-EHEs.