Emerging Divergence Between Dry‐ and Humid‐Heat in China Under Weakening Temperature‐Humidity Coupling

This is the authors' abstract. We don't add key points for this paper.

Global warming has weakened the relationship between temperature and humidity, making dry‐ and humid‐heat increasingly distinct in China. Here, based on ERA5 hourly reanalysis data, the extreme dry‐ and humid‐heat events (EDHE/EHHE) at sub‐daily scale are first identified, and their spatiotemporal patterns as well as the associated underlying mechanisms across different climate regimes in China during 1961–2024 are investigated. Results indicate that both EDHE and EHHE exhibit an increasing trend, but with a greater magnitude for EHHE. Spatially, EDHE predominantly occurs in northern China, whereas EHHE mainly dominates southern China. These regional contrasts are closely linked to distinct circulation regimes and land‐atmosphere interactions. High‐frequency years of EDHE in both northern and southern China are accompanied by pronounced subsidence, which is maintained and reinforced by local land–atmosphere coupling (LAC) in both regions but considerably more strongly in southern China. During years with frequent EHHE, contrasting large‐scale environments are observed between the two regions: large‐scale circulation favors convective activities in northern China but tends to suppress convection in southern China. LAC may also contribute to EHHE in northern China, while its role in southern China remains uncertain and warrants further investigation. Overall, this study highlights pronounced regional differences in the mechanisms governing EDHE and EHHE, providing new insights into the processes driving compound heat extremes and offering guidance for improving their prediction under a warming climate.