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东北冷涡活动的季节内振荡特征及其影响

ISSN号：1006-9895
期刊名称：大气科学
时间：0
页码：959-973
分类：P466[天文地球—大气科学及气象学]
作者机构：[1]南京信息工程大学,南京210044, [2]中国气象局中国气象科学研究院灾害天气国家重点实验室,北京100081
相关基金：国家重点基础研究发展计划项目（973）2012CB417205,国家公益性行业（气象）专项GYHY200906017,国家自然科学基金资助项目40921003,中国气象科学研究院基本科研业务费20102003
相关项目：东亚副热带季风变异机理

关键词：东北冷涡, 季节内振荡, 中国东部降水, northeast cold vortex, intraseasonal oscillation, precipitation over eastern China

中文摘要：

东北冷涡是造成我国东北地区低温冷害、持续性阴雨和突发性强对流的重要天气系统。利用1979～2009年NCEP／NCAR逐日再分析资料和中国气象科学研究院提供的中国区域高分辨率格点降水资料，定义了一个客观描述东北冷涡活动的指数（NEcvI），并基于该指数分析了东北冷涡活动的低频特征及其与相关环流和降水的关系。结果表明，东北冷涡活动具有显著的10 ～30天振荡周期。与东北冷涡活动相关的大气环流的10～30天振荡和我国东部夏季降水异常具有明显的锁相关系，对雨带的位置起着重要的调制作用，在东北冷涡及其相关低频环流由西北向东南的移动过程中，我国东部也经历一次由北至南的降水过程。本文还进一步讨论了东北冷涡的低频活动与中高纬大气环流遥相关型的关系。与东北冷涡相联系的低频环流是夏季低频欧亚（EU）型遥相关波列的一部分，低频欧亚型（EU型）与东亚／太平型（EAP型）遥相关波列在东亚地区交汇，并通过波列之间的相互作用影响东北冷涡低频系统的移向和移速，进而影响中国东部降水的位置与维持时间。因而前期ELI型和EAP型低频波列的发展情况可能预示着后期中国东部各个区域降水的演变。本文研究结果将为提高我国东部强降水的1～2周延伸期天气预报提供参考。

英文摘要：

The Northeast Cold Vortex （NECV） is a major synoptic system that causes chilling damage, sustained rainfall and sudden severe convective storms over Northeast China. By using the National Centers of Environmental Prediction-National Center for Atmospheric Research （NCEP-NCAR） reanalysis data and high resolution gridded precipitation data over China provided by the Chinese Academy of Meteorological Sciences, an objective index of the NECV （NECVI） is defmed, and then the characteristics of the northeast cold vortex activities on intraseasonal timescale and its relationship with the circulation and rainfall are investigated. Results show that the activities of the NECV exhibit remarkable 10-30-day oscillation. The 10-30-day oscillation of atmosphere circulation associated with the NECV activities obviously locks with the precipitation anomalies over eastern China, and modulates the locations of anomalous rain belts. The anomalous rain belts over eastern China shift from north to south along with the northwest-southeast movements of the NECV and associated low frequency circulation. Moreover, the relationship between the 10-30-day activities of the NECV and the atmospheric teleconnection patterns in mid-high latitudes is discussed. The low frequency circulation associated with the NECV is one part of the Eurasian （EU） pattern teleconection-like wave train in summer. The EU wave train converges with the East Asian-Pacific （EAP） pattern teleconnetion-like wave train in eastern Asia. The interaction between them affects the velocity and direction of low frequency system related with the NECV, and further determines the location and duration of precipitation over eastern China. Therefore, the preceding development of the low frequency wave trains of EU pattern and EAP pattern might indicate the following stage of rainfall over eastern China. This study will provide a reference for the 10-30-day extended-range weather forecast of severe precipitation over eastern China.

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