Causes of the 2022 Yangtze–Huaihe River basin drought: A comparative study with the 2020 flood

Abstract In summer 2022, the Yangtze–Huaihe River Basin (YHRB) experienced an extreme drought accompanied by persistent heatwaves. Previous studies have highlighted the influence of the Western Pacific subtropical high (WPSH). However, a similarly strong and westward‐extended WPSH also occurred in summer 2020, when the YHRB instead received excessive rainfall, implying that the WPSH anomaly alone cannot explain the 2022 precipitation deficit and heat extremes. We show that the 2022 drought was more directly linked to a robust mid‐to‐upper‐tropospheric continental anticyclone (heat dome) that exhibited pronounced intraseasonal variability yet persisted for nearly a month in August. Using the Multiscale Window Transform (MWT) and localized multiscale energetics diagnostics, we find that the heat dome was primarily maintained by enhanced Tibetan Plateau (TP) thermal forcing. The in‐phase relationship between intraseasonal temperature and meridional wind anomalies, acting on an intensified background temperature gradient associated with TP heating, favored baroclinic instability and enabled efficient transfer of available potential energy from the background (>64 days) to the intraseasonal window (16–64 days). The resulting barotropic high caused a severe precipitation deficit over the YHRB throughout August, intensifying the 2022 summer drought. Further analysis shows that spring–summer TP mid‐tropospheric temperature is strongly correlated with YHRB heatwave variability, and a linear baroclinic model reproduces the observed heat‐dome response to TP thermal forcing. Overall, our results highlight the critical role of TP thermal conditions in shaping YHRB drought and heatwave extremes.