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低频振荡对2015年春季云南东部降水异常的影响
陈艳, 张万诚, 陶云, 任菊章, 段长春
(云南省气象科学研究所)
The Influence of Low-frequency Oscillation on the Abnormal Precipitation over Eastern Yunnan in the Spring of 2015
CHEN Yan, ZHANG Wangcheng, TAO Yun, REN Juzhang, DUAN Changchun
(Yunnan Institute of Meteorological Sciences)
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投稿时间:2020-04-12    修订日期:2020-12-11
中文摘要: 以往的研究显示,厄尔尼诺是导致云南春季干旱的重要原因。2015年,在超强厄尔尼诺事件背景下,滇西大部春季降水偏少,雨季开始偏晚至特晚;然而,东部地区降水总体偏多,部分区域雨季开始偏早至特早,东西部形成了鲜明对比。利用云南省逐日观测降水、全球测站均一化逐日格点降水和NCEP/NCAR再分析资料,运用统计和动力诊断方法,研究了2015年春季10~30 d大气低频振荡特征及其对云南东部降水异常的影响。分析显示,3月中旬至4月下旬,100°E以东地区10~30 d大气低频振荡异常活跃,是造成云南东部地区降水偏多的重要原因。在低频振荡影响下,云南东部先后出现了3次明显的降水过程,每一次过程都与欧亚型波列上低频冷位相的南压密切相关。即当低频冷位相向南移动时,东亚副热带西风急流随之南压,当其入口区次级环流上升支移至云南上空,并与南下冷高压西南侧有利的回流水汽相互作用时即形成了降水。
Abstract:Previous literatures suggest that El Nin ?o is a dominant factor causing spring drought in Yunnan province. Under the background of super-strong El Ni?o event during 2015, the spring (March-May) precipitation in most parts of western Yunnan province is below normal, and the rainy season starts late to very late. However, the precipitation in eastern part is generally abundant, and the rainy seasons in some regions start early to very early, presenting a sharp contrast between the east and west. By using daily rain gauge precipitation of Yunnan province, the CPC (Climate Prediction Center, USA) Global Unified Gauge-Based Analysis of Daily Precipitation and NCEP/NCAR (National Centers for Environmental Prediction/ National Center for Atmospheric Research) reanalysis data, the influence of 10-30-day atmospheric oscillation on the spring abnormal precipitation over eastern Yunnan was studied through statistical and dynamical diagnosis methods. The analysis showed that the 10-30-day oscillation was active to the east of 100°E, from mid-March to late-April, which is a major reason for the abnormal abundant precipitation over eastern Yunnan. Three distinct precipitation processes in eastern Yunnan happened associated with the southward approaching of the low-frequency cold cell that embedded in the Eurasian pattern (EU) wave train from the mid- and high- latitudes of East Asia. Namely, when the upward branch of the secondary circulation around the subtropical westerly jet entrance interacted with the reflux vapor on the southwestern fringe of the cold high, the rainfall process was formed.
文章编号:202004120114     中图分类号:    文献标志码:
基金项目:国家自然科学基金(41790471,41965005,42075013)
引用文本:
陈艳,张万诚,陶云,任菊章,段长春,0.The Influence of Low-frequency Oscillation on the Abnormal Precipitation over Eastern Yunnan in the Spring of 2015[J].Meteor Mon,():-.
CHEN Yan,ZHANG Wangcheng,TAO Yun,REN Juzhang,DUAN Changchun,0.The Influence of Low-frequency Oscillation on the Abnormal Precipitation over Eastern Yunnan in the Spring of 2015[J].Meteor Mon,():-.