Dynamical Amplification of Summer East Asian Heatwaves by Ural Blocking and Its Intensification Under Global Warming

Extreme heatwaves in East Asia have intensified in recent decades, yet the extent to which upstream Ural Blocking (UB) amplifies these events has not been fully quantified. Based on ERA5 reanalysis and CMIP6 outputs, this study systematically quantifies the amplification effect of UB on summer East Asian heatwaves and examines its changes under future climate warming, and the associated dynamical mechanisms are further investigated. The results show that the UB acts as a key dynamical amplifier of East Asian heatwaves. Under the UB-related conditions, the heatwave intensity, duration, accumulated area, and maximum 2m temperature (T2m) anomaly all increase significantly. Such conditions are regulated by negative anomalies in the meridional potential vorticity gradient (PVy) over the Ural region, which facilitate the eastward propagation of Rossby waves and strengthen energy transport to East Asia, thereby further amplifying heatwaves. Additionally, the UB-related amplification is projected to strengthen under future climate warming. Under the SSP585 scenario, the UB amplification effects are projected to increase by 36% in intensity, 57% in duration, 21% in accumulated area, and 67% in maximum T2m anomaly relative to the historical baseline. Future changes in the PVy and increased blocking frequency further strengthen the dynamical coupling between the UB and East Asian heatwaves, thereby exacerbating the risk of extreme heat across regions. in press