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| 青藏高原大气热源和冬春积雪与中国东部降水的年代际变化关系 | |
| 引用本文： | 朱玉祥,丁一汇,徐怀刚.青藏高原大气热源和冬春积雪与中国东部降水的年代际变化关系[J].气象学报,2007,65(6):946-958. |
| 作者姓名： | 朱玉祥 丁一汇 徐怀刚 |
| 作者单位： | 1. 中国气象科学研究院,北京,100081;南京信息工程大学,江苏,南京,210044;中国气象局培训中心,北京,100081 2. 国家气候中心,北京,100081 3. 中国气象局培训中心,北京,100081 |
| 基金项目： | 国家科技攻关计划;国家自然科学基金 |
| 摘 要： | 利用NCEP 1950—2004年逐日再分析资料,采用倒算法,对青藏高原大气热源的长期变化进行了计算,结果发现,青藏高原及附近地区上空大气春夏季热源在过去50年里,尤其是最近20年,表现为持续减弱的趋势。而1960—2004年青藏高原50站的冬春雪深却出现了增加,尤其是春季雪深在1977年出现了由少到多的突变。用SVD方法对高原积雪和高原大气热源关系的分析表明,二者存在非常显著的反相关关系,即高原冬春积雪偏多,高原大气春夏季热源偏弱。高原大气春夏季热源和中国160站降水的SVD分析表明,高原大气春夏季热源和夏季长江中下游降水呈反相关,与华南和华北降水呈正相关;而高原冬春积雪和中国160站降水的SVD分析显示,高原冬春积雪和夏季长江流域降水呈显著正相关,与华南和华北降水呈反相关。在年代际尺度上,青藏高原大气热源和冬春积雪与中国东部降水型的年代际变化(南涝北旱)有很好的相关。最后讨论了青藏高原大气热源影响中国东部降水的机制。青藏高原春夏季热源减弱,使得海陆热力差异减小,致使东亚夏季风强度减弱,输送到华北的水汽减少,而到达长江流域的水汽却增加;同时,高原热源减弱,使得副热带高压偏西,夏季雨带在长江流域维持更长时间。导致近20年来长江流域降水偏多,华北偏少,形成"南涝北旱"雨型。高原冬春积雪的增加,降低了地表温度,减弱了地面热源,并进而使得青藏高原及附近地区大气热源减弱。 |
| 关 键 词： | 高原热源 季风 高原积雪 南涝北旱 |
| 收稿时间： | 2006/3/28 0:00:00 |
| 修稿时间： | 2006年3月28日 |
THE DECADAL RELATIONSHIP BETWEEN ATMOSPHERIC HEAT SOURCE OF WINTER AND SPRING SNOW OVER TIBETAN PLATEAU AND RAINFALL IN EAST CHINA |
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| Zhu Yuxiang,Ding Yihui and Xu Huaigang.THE DECADAL RELATIONSHIP BETWEEN ATMOSPHERIC HEAT SOURCE OF WINTER AND SPRING SNOW OVER TIBETAN PLATEAU AND RAINFALL IN EAST CHINA[J].Acta Meteorologica Sinica,2007,65(6):946-958. | |
| Authors: | Zhu Yuxiang Ding Yihui and Xu Huaigang |
| Abstract: | By adopting reverse computation method,the calculation and analysis from NCEP/NCAR daily reanalysis data from 1960 to 2004 show that,atmospheric heat sources over Tibetan Plateau(TP) and its neighboring areas take on a persistent downtrend in spring and summer during the foregone 50 years,especially latest 20 years.While snow depth at 50 stations over TP in winter and spring represents an increase,especially the snow depth in spring exhibits a sharp increase after the late 1970s.A close negative correlation exists between snow cover and atmospheric heat source over TP and its neighboring areas by SVD method,namely if there is more snow on TP,then weaker atmospheric heat source over TP.The SVD analysis between atmospheric heat source over TP in spring and summer and rainfall at 160 stations indicates that,the former has negative correlation with precipitation in the middle and lower Yangtze River,and has positive correlation with South China and North China;Also from the results of SVD analysis,atmospheric heat source over TP in winter and spring and rainfall at the same 160 stations indicates that,the former has marked positive correlation with precipitation in the middle and lower Yangtze River,and reversed correlation in South China and North China.In the decadal years scale,the atmospheric heat source and winter and spring snow over TP has close correlation with decadal precipitation pattern shift(southern flood and northern drought) in East China.In the end of the article,it is discussed the mechanism how atmospheric heat source over Tibetan Plateau influence rainfall in East China.The weakening of atmospheric heat source over TP in winter and spring can reduce the heat difference between ocean and continent,leading to weaker East Asian summer monsoon,which brings less water vapor to North China and more water vapor to Yangtze River valley;Simultaneously the weakening of atmospheric heat source over TP render the position of subtropical high more westward and rainbelt to last more time,which cause more rainfall in Yangtze River valley and less rainfall in North China,namely southern flood and northern drought in latest 20 years.The increasing of snow over TP brings about the weakening of atmospheric heat source over TP.Possible physical mechanism is as follows.In the early stage of snow,surface reflectivity is dominant.After snow melts,"Moist Soil" contributes to the prolonged influence process of snow on weather and climate.The reduction of absorbing solar radiation due to the increased reflectivity,the more needing heat when snow melts,and the long-term interaction between moist soil and atmosphere change the heat source of the TP,which is the main influencing mechanism of snow on atmospheric heat source over TP. |
| Keywords: | Tibetan Plateau heat source Monsoon Southern flood and northern drought Snow simulation Tibetan Plateau snow |
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