The Impacts of Regime Shift in Summer Arctic Oscillation on Precipitation in East Asia

• Published in: Atmosphere
• Main Authors: Xuxin Zou, Li Yan, Jianjun Xu, Shaojun Zheng
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2024
• Subjects: Arctic Oscillation; East Asia; summer precipitation; regime shift; water vapor transport; wave activity flux; Meteorology. Climatology; QC851-999; Arctic; North Atlantic
• Online Access: https://doi.org/10.3390/atmos15030283; https://doaj.org/article/3d67a6ac8fd2435b923c15b64e30504c

Using multiple observational and reanalysis data, this paper investigates the impact of the interdecadal shift in summer Arctic Oscillation (AO) on precipitation in East Asia, by removing ENSO influences. The results indicate that the lower-layer activity center of summer AO in Atlantic shifted eastward after the mid-1980s. This regime shift of summer AO has a significant impact on precipitation in East Asia. Before the mid-1980s, the key regions in which precipitation was affected by AO in East Asia were northern East Asia and Northeastern China and adjacent regions. After the mid-1980s, the key regions in which precipitation was affected by AO in East Asia were central Inner Mongolia and Southern China. The mechanism of precipitation changes can be attributed to changes in atmospheric circulation and water vapor transport related to AO changes. After the mid-1980s, the influence of AO on geopotential height over northern East Asia weakened; meanwhile, the impact of AO on geopotential height over China increased. Consistent with the changes in atmospheric circulation, water vapor transport in East Asia also underwent interdecadal changes before and after the mid-1980s. The differences in atmospheric circulation and water vapor transport in East Asia can be traced back to the North Atlantic. Before the mid-1980s, wave activity flux related to summer AO tended to propagate in high latitudes and subtropics; after the mid-1980s, the wave activity flux changed in its subtropical path and propagated eastward from the North Atlantic through the Middle East to China, significantly affecting the summer precipitation in China.