This study investigates the evolution of an extreme anomalous anticyclone (AA) event over Northeast Asia, which was one of the dominant circulation systems responsible for the catastrophic extreme precipitation event in July 2021 in Henan, and further explores the significant impact of this AA on surface temperatures beneath it. The results indicate that this AA event over Northeast Asia was unprecedented in terms of intensity and duration. The AA was very persistent and extremely strong for 10 consecutive days from 13 to 22 July 2021. This long-lived and unprecedented AA led to the persistence of warmer surface temperatures beyond the temporal span of the pronounced 500-hPa anticyclonic signature as the surface air temperatures over land in Northeast Asia remained extremely warm through 29 July 2021. Moreover, the sea surface temperatures in the Sea of Japan/East Sea were extremely high for 30 consecutive days from 13 July to 11 August 2021, persisting well after the weakening or departure of this AA. These results emphasize the extreme nature of this AA over Northeast Asia in July 2021 and its role in multiple extreme climate events, even over remote regions. Furthermore, possible reasons for this long-lasting AA are explored, and it is suggested to be a byproduct of a teleconnection pattern over extratropical Eurasia during the first half of its life cycle, and of the Pacific–Japan teleconnection pattern during the latter half.

本研究调查了东北亚极端异常反气旋（AA）事件的演变，该事件是造成2021年7月河南灾难性极端降水事件的主导环流系统之一，并进一步探讨了该AA对地表的重大影响其下方的温度。结果表明，此次东北亚防空事件的强度和持续时间是前所未有的。 2021 年 7 月 13 日至 22 日，连续 10 天的 AA 非常持久且极其强烈。这种持续时间长且史无前例的 AA 导致地表温度持续升高，超出了明显的 500 hPa 反气旋特征的时间跨度，因为地表空气到2021年7月29日，东北亚陆地气温仍然极端温暖。此外，2021年7月13日至8月11日，日本海/东海的海面温度连续30天极高，并且在减弱或离开后仍持续很长时间这个AA。这些结果强调了 2021 年 7 月东北亚上空这次 AA 的极端性质及其在多个极端气候事件中的作用，甚至在偏远地区也是如此。此外，还探讨了这种长期AA的可能原因，并认为它是其生命周期前半段温带欧亚大陆遥相关模式和后半期太平洋-日本遥相关模式的副产品。