大气科学2025，Vol.49Issue(4)：1030-1045,16.DOI:10.3878/j.issn.1006-9895.2403.23106
梅雨期东亚副热带西风急流纬向振荡特征
Characteristics of Zonal Oscillation of the East Asian Subtropical Westerly Jet during the Mei-yu Period
摘要
Abstract
This study analyzes the zonal oscillation characteristics of the East Asian subtropical westerly jet and its relationship with the East Asian atmospheric circulation and precipitation during the Mei-yu period using the EAR5 daily reanalysis data and observational precipitation data at 2437 stations in China from 1979 to 2020.The results reveal two intensity and position variation types for the East Asian subtropical westerly jet during the Mei-yu period by comparing the 200 hPa regional mean zonal wind anomalies in an area(37°-47°N,100°-120°E)with a large standard deviation with the two jet stream centers over the western Pacific(37°-47°N,140°-160°E)and the Qinghai-Xizang Plateau(37°-47°N,80°-100°E).The jet stream center of the first type is located over the western Pacific in the early stage;subsequently,the intensity of the jet stream over the western Pacific weakens,and an enhanced jet stream center appears on the western side of the jet stream.Because the maximum zonal wind migrates rapidly westward,this type is called the rapid westward migration type.The second type of jet stream center is initially located over the Qinghai-Xizang Plateau,but it then strengthens steadily and moves eastward.As the maximum zonal wind exhibits a gradual eastward migration feature,it is referred to as the gradual eastward migration type.The analyses of circulation and precipitation corresponding to the two jet stream oscillation types indicate that with the rapid westward migration of the jet stream,the east ridge point of the South Asian High is located to the east,and the intensity of the western Pacific Subtropical High increased and moved westward;the circulation pattern in the middle and high latitudes is characterized as"two troughs and one ridge".Furthermore,as the meridional increase of 200 hPa divergence and the 700 hPa water vapor transport rises to the north,the position of the rain belt shifts from the south to the north.For the gradual eastward migration type,the east ridge point of the South Asian High is located to the west,and the intensity of the western Pacific Subtropical High decreased and contracted to the east;the circulation pattern in the middle and high latitudes is characterized as"two ridges and one trough",and the blocking highs occurred more frequently over the Okhotsk Sea region.Meanwhile,the upper-level divergence in the lower reaches of the Yangtze River weakens.In contrast,the upper-level divergence and lower-level water vapor transport strengthen in the upper reaches of the Yangtze River,forming an antiphase change in precipitation intensity between the upper and lower reaches of the Yangtze River.关键词
东亚副热带急流/纬向振荡/环流变化/降水分布Key words
East Asian subtropical jet/Zonal oscillation/Circulation evolution/Precipitation distribution分类
天文与地球科学引用本文复制引用
郑淇丹,张耀存..梅雨期东亚副热带西风急流纬向振荡特征[J].大气科学,2025,49(4):1030-1045,16.基金项目
国家自然科学基金项目41930969 National Natural Science Foundation of China(Grant 41930969) （Grant 41930969）
