摘要
利用1961—2005年逐候资料对东亚副热带西风急流初夏至盛夏变化与江淮出梅的关系进行了分析。结果表明,多年平均7月初夏至盛夏急流中心由西太平洋地区西跳至青藏高原的同时我国东部地区急流北跳至37.5°N以北,比梅雨结束早1候;急流北跳使得我国东部高空强辐散中心北移至华北地区,江淮地区上空辐散显著减弱,上升运动减弱,从而使得江淮梅雨结束,雨带北移;而急流中心的西跳仅使得我国东部地区高空辐散中心减弱,降水减弱,有利于雨带北移。我国东部急流北跳与江淮地区梅雨结束时间显著正相关,在北跳偏早(晚)年份梅雨结束早(晚),长江中下游地区降水偏少(多),而急流中心西跳早晚对我国华北北部地区和淮河附近地区降水有较大影响。可见,我国东部急流北跳与梅雨结束关系密切,可作为梅雨结束的先期信号。
Based on the pentadly averaged datasets from 1961 to 2005 year, the relationship between the variations of the East Asian subtropical westerly jet （EASWJ） from early summer to midsummer and the withdrawal of Mei-Yu from the Jianghuai region are studied, with the results as follows ： （ 1 ） during the transforming process of the EASWJ from early summer to midsummer, the westward jump of the jet core from the western Pacific to the Qinghai-Tibet Plateau, and the northward jump of the jet to the area north of 37.5°N over eastern China took place simultaneously at early July on the multi-year average condition;and the jump time is usually one pentad earlier than the date of the withdrawal of Mei-Yu from the Jianghuai region. （2）the northward jump of the jet led to the northward movement of strong divergence center at upper level to North China, meanwhile to the weakening of the upper level divergence and surface precipitation over the Changjiang-Huaihe River Basin, thus the end of Mei-Yu and the northward shift of the rain belt; whereas the westward jump of the jet core is conducive to the northward movement of the rain belt. （3） the date of the northward jump of the jet over eastern China is remarkably positively correlated with the date of the withdrawal of Mei-Yu, viz. the withdrawal took placeearlier（ later）, the Mei-Yu ended earlier（later） and the precipitation of July in the middle-lower reaches of the Yangtze River was less （more） ; the date of the westward jump of the jet core is remarkably related to July anomalous precipitation in the northern of North China and the Huaihe River Basin. So the relationship between the northward jump of the jet over eastern China and the withdrawal of Mei-Yu is closer,and the former can be used as a precursor for the end of Mei-Yu.
出处
《大气科学学报》
CSCD
北大核心
2010年第1期74-81,共8页
Transactions of Atmospheric Sciences
基金
国家自然科学基金重点资助项目(40675041)
关键词
东亚副热带西风急流
初夏至盛夏变化特征
江淮出梅
East Asian subtropical westerly jet
variations of EASWJ from early summer to midsummer
withdrawal of Mei-Yu from the Jianghuai region
