| 摘要: |
| 本文根据青藏高原主体72个气象站日测资料建立的积雪序列分析了高原积雪对长江流域夏季降水的影响,高原冬春积雪异常与长江流域汛期特别是6、7月降水呈显著的正相关关系.青藏高原冬春多雪年,随后夏季多出现Ⅱ、Ⅲ类雨型,长江中游和下游鄱阳湖地区多偏涝;青藏高原冬春少雪年,随后夏季多出现Ⅰ、Ⅱ类雨型,长江下游鄱阳湖地区多偏旱,长江中游多正常偏旱.多(少)雪年东亚洲大陆上空的气温明显偏低(高),而大陆南部海洋上空的气温明显偏高(低),降低(增加)了陆海温差,延迟(促进)了东亚夏季风的到来,一定程度上减弱(加强)东亚季风的强度.多(少)雪随后夏季,由于南亚夏季风和东亚夏季风都明显减弱(增强),对流层中低层从孟加拉湾吹向中南半岛的西南风减弱(增强),我国大陆东部的南风也明显减弱(增强),西太副高偏南(北);青藏高原东南侧到中南半岛北部的上升运动较弱(强),长江中下游及其以东洋面上升运动较强(弱),长江中下游地区多(少)雨. |
| 关键词: 积雪 青藏高原 夏季降水 长江流域 |
| DOI：10.18307/2003.sup08 |
| 分类号: |
| 基金项目:中国科学院知识创新工程重要方向项目(ZKCX2-SW-210)资助 |
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| Influences of the Winter-Spring Snow from the Tibetan Plateau on the Summer Rainfall of the Yangtze River Basin |
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WEI Zhigang
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Cold and Arid Regions Environmental and Engineering Research Institute, CAS, Lanzhou 730000, P. R. China
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| Abstract: |
| In this paper, we analyze the influences of the winter-spring snow (WSS) on summer rainfall in the basin of the Yangtze River using the daily snow depths of 72 weather stations in Qinghai Province and the Tibet Autono-mous Region. The variations of the atmospheric circles of the anomalous Tibetan WSS years are investigated. The impact mechanism is researched by using NCAR/NCEP data. The most obvious area where the Plateau snow influences on summer precipitation in China is the Yangtze River Basin. Much (little) summer rain occurs in the Middle and lower reaches of the Yangtze River, the Ⅱ and Ⅲ (Ⅰ and Ⅱ) types of Chinese summer rain usually occur following the rich (little) winter-spring snow. The difference in air temperature over the Plateau between the rich and little WSS years occur mainly in March and April. In the rich (little) Tibetan WSS, the air temperature is low (high) over East Asia and high (low) over the ocean to the south part of East Asia in late spring and early summer especially in April and May. Hence, the air temperature difference between land and ocean is low (high). This retards (accelerates) the onset of the East Asian summer monsoon and makes it weak (strong) to a certain degree in the rich (little) snow year. In the spring and summer of the rich (little) Tibetan WSS year, the lower (higher) surface heat (mainly sensible heat) weakens (strengthens) the ascending motion over the Plateau and strengthens (weakens) the ascending motion over the middle and lower area of the Yangtze River and the west Pacific Ocean to the south of Japan. This restrains (accelerates) the West Pacific Ocean sub-tropical high from moving to the north. As a result, there is much (little) rain in the middle and lower area of the Yangtze River. |
| Key words: Snow Tibetan Plateau summer precipitation The Yangtze River Basin |
