Features of Regional Compound Dry‐Hot Events over the Yangtze River Basin in Warm Season and Related Mechanisms

Abstract Based on daily station observations and ERA5 reanalysis data during warm seasons of 1961–2024, the characteristics of regional compound dry‐hot events (RCDHEs) and associated mechanisms over Yangtze River Basin (YRB) have been systematically explored. Results show more than 45% of the total occurrence days (OD) of compound dry‐hot events (CDHEs) over most YRB in warm season is contributed by the RCDHEs, which show distinct sub‐seasonal variations and concentrate in mid‐June to mid‐July. The coverage rate (CR), intensity and OD of RCDHEs all show significant increasing trends during 1961–2024, especially as the intensity and OD increase at much faster rates after 2000. Moreover, the occurrences of RCDHEs are mainly driven by two synoptic patterns named P1 and P2, respectively. The P1 (P2) pattern features that the intensified Western Pacific Subtropical High and South Asian High with southerly (northerly) location relative to the climatology move toward each other. Meanwhile, the intensity, CR and OD of RCDHEs under both P1 and P2 patterns all show increasing trends during 1961–2024, and the accelerated increasing rates of the intensity and OD after 2000 are mainly contributed by those under the P1 pattern. Mechanism analysis reveals that the decreased cloud cover and precipitation in southern (central‐eastern) YRB due to the subsidence induced by the abnormal high pressure under the P1 (P2) pattern enhance the surface net shortwave radiation and heating there, further leading to much higher occurrence probability of CDHEs in southern (central‐eastern) YRB during the RCDHEs under the P1 (P2) pattern.