Century‐long variations of growing‐season compound dry–hot extremes and their links with large‐scale climate patterns in China

In the context of global warming, the increasing frequency of compound dry–hot extremes pose varying degrees of threats to the natural environment and human society. However, due to the lack of long‐term and high‐accuracy meteorological observations, the characteristics and drivers of compound dry–hot extremes over a century‐long period is still poorly investigated in China. Here we characterize the spatiotemporal variations of growing‐season (May–September) compound dry–hot events (CDHEs) over China using Standardized Dry and Hot Index (SDHI) calculated by monthly temperature and precipitation during 1901–2017. The influences of precipitation and temperature extremes, as well as large‐scale climate indices (i.e., El Niño–Southern Oscillation Index [ENSO], Atlantic Multidecadal Oscillation [AMO], North Atlantic Oscillation [NAO], Pacific Decadal Oscillation [PDO] and North Pacific [NP]) on CDHEs were then explored using the relative contribution analysis, Pearson correlation analysis and cross‐wavelet spectrum analysis. Our findings reveal a significant increase in the occurrence of different severity levels of CDHEs in China with their spatial extent gradually increase, practically since the end of the 20th century. Due to the exacerbation of drought conditions in China since the mid‐20th century, the regions where the Standardized Precipitation Index (SPI) has a more prominent contribution to the SDHI have gradually expanded, predominantly in the eastern, northern and northwestern parts of China. The significant influence of large‐scale climate indices, particularly ENSO and AMO, on the occurrence of compound dry–hot extremes in China is noteworthy, as these indices control the variability of precipitation and temperature, respectively. The study findings demonstrate that AMO exhibits a more significant correlation with SDHI in all subregions of China, while ENSO exhibits marginally stronger periodic coherence with SDHI than the other indices. This study offers valuable insights and references for unravelling long‐term development process of and the underlying influence mechanisms of significant climate patterns on the growing‐season CDHEs in China. The occurrence and spatial extent of different level compound dry–hot extremes increased significantly in China over a century‐long period. All five large‐scale climate patterns consistently exhibit periodic coherence with SDHI, where ENSO exhibits stronger periodic coherence than the others.