| 藏北冬季降水异常的大尺度环流特征及影响因子 |
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| 引用本文： | 尼玛吉,柯宗建,陈丽娟,次仁央宗.藏北冬季降水异常的大尺度环流特征及影响因子[J].高原气象,2021,40(1):28-36. |
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| 作者姓名： | 尼玛吉 柯宗建 陈丽娟 次仁央宗 |
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| 作者单位： | 西藏自治区气候中心,西藏拉萨850001;国家气候中心中国气象局气候研究开放实验室,北京100081;国家气候中心中国气象局气候研究开放实验室,北京100081;国家气候中心中国气象局气候研究开放实验室,北京100081;南京信息T程大学气象灾害预报预警与评估协同创新中心,江苏南京210044 |
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| 基金项目： | 国家重点研发计划项目(2018YFC1505603);公益性行业(气象)科研专项(GYHY201306024);国家自然科学基金项目(41005051,41730964)。 |
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| 摘 要： | 利用西藏高原气象台站降水和积雪观测资料、NCEP/NCAR再分析资料和NOAA海温资料等,分析了藏北高原地区冬季降水异常的大尺度环流特征及影响因子。结果表明:藏北地区冬季降水存在2~4年周期性变化特征,其中3年的周期信号最强。降水偏多年,欧亚中高纬乌拉尔山至贝加尔湖附近500 hPa高度距平场呈现"西低东高"分布型,影响我国的冷空气路径偏西,西藏高原高度场偏低;高原上游中东急流偏强,高原南支绕流偏强,南支槽活跃。藏北地区冬季降水与同期中东急流的关系非常密切,相关系数达到0.61。进一步分析表明,冬季北极涛动正位相有利于冷空气路径偏西影响高原地区,高原上游中东急流偏强偏南,而赤道中东太平洋海温偏高也有利于中东急流呈偏强偏南的特征。北极涛动和ENSO位相的协同作用对藏北地区冬季降水的多寡起到重要的作用。
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| 关 键 词： | 藏北 冬季降水 中东急流 |
Large-Scale Circulation Characteristics and Influence Factors of Winter Precipitation Anomaly in the Northern Tibet |
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| Institution: | (Tibet Climate Center,Lhasa 850001,Tibet,China;Laboratory for Climate Studies,National Climate Center,CMA,Beijing 100081,China;Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China) |
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| Abstract: | Precipitation and snow cover data in weather observation site in Tibet,NCEP/NCAR reanalysis data and sea surface temperature data from NOAA are used to analyze the large-scale circulation and influence factors resulting in precipitation anomaly in winter in the Northern Tibet. Results show that there is a periodic variation with 2~4 years in winter precipitation in the Northern Tibet,and 3 years period is the strongest. In more rain years,a west-negative and east-positive spatial distribution of geopotential height anomaly at 500 hPa level is shown over the mid-high latitudes of the Eurasian continent from the Ural Mountains to the Lake Baikal nearby.The path of cold air influencing China shifts west. Geopotential height at 500 hPa level over the Tibetan Plateau shows negative anomaly. The Middle East jet stream(MEJS)is stronger than normal. The southern branch of westerly flow around the Tibetan Plateau is stronger than normal,and the southern branch trough is more active.Winter precipitation in the Northern Tibet is closely related to the strength of MEJS. The correlation coefficient between them is up to 0. 61. Further analysis shows that the phase of arctic oscillation(AO)has an impact on the path of cold air. Positive phase of AO is conducive to west path of cold air affecting the Tibetan Plateau. Meanwhile,The MEJS is stronger and southern than normal. In addition,warmer sea surface temperature in the central and eastern tropical Pacific is conducive to a stronger and southern MEJS. The synergetic effects of AO and ENSO phase play a key role in the precipitation anomaly in winter in the Northern Tibet. |
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| Keywords: | Northern Tibet precipitation in winter MEJS |
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