Changes of Compound Droughts and Heatwaves Events and Their Driving Factors in the Jianghuai Region, China

ABSTRACT With the continuous warming of the global climate, the frequency of Compound Droughts and Heatwaves (CDHWs) is increasing across the world. The Jianghuai Region of China experiences frequent CDHWs, while research on CDHW events is relatively limited. This study upgrades the regional mechanistic understanding by moving beyond statistical analysis to a complete process‐chain perspective. We first analysed the spatiotemporal characteristics and influencing factors of CDHWs in the Jianghuai Region of China from 1961 to 2018. CDHWs were identified using the Standardised Precipitation Index (SPI) and daily maximum temperature and their frequency, duration and intensity were analysed with Empirical Orthogonal Function (EOF) analysis. And then the study systematically explored the occurrence mechanisms of CDHWs in the Jianghuai Region by analysing the impacts of water and energy characteristics, land‐atmosphere coupling, circulation patterns and sea surface temperature modes (mainly ENSO) on the CDHWs. The results are as follows: (1) The frequency of CDHWs showed a downward trend, while the intensity showed an upward trend. The first mode exhibited a uniform pattern across the region, while the second mode showed a dipole structure; (2) In the typical strong years, increased sensible heat flux, decreased latent heat flux and enhanced high‐pressure systems exacerbated drought and heat conditions in the region; (3) CSISM‐SLHF showed positive anomalies, indicating ‘moisture‐limited’ land‐atmosphere coupling in the typical strong years, while the land‐atmosphere coupling was ‘energy‐limited’ in the typical weak years; (4) Anomalously low sea surface temperatures in the eastern Pacific (i.e., La Niña events) significantly impacted CDHWs in the strong years. The dynamic mechanism involved the coupling of the Walker and Hadley circulations, which ultimately affected vertical motion and the WPSH in the Jianghuai Region. The findings established a process‐oriented predictive framework for CDHWs and provided a scientific basis for monitoring, early warning and adaptation strategies against such compound extremes in the Jianghuai Region.