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ISSN 1006-9895

CN 11-1768/O4

青藏高原冬季积雪影响我国夏季降水的模拟研究
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“十一五” 国家科技支撑项目2007BAC03A01, 国家自然科学基金资助项目40805026、 40705033, 国家重点基础研究发展计划项目2007CB411505, 2008年JICA加密观测试验在数质预报中的应用研究2008Z006


Simulation of the Influence of Winter Snow Depth over the Tibetan Plateau on Summer Rainfall in China
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    摘要:

    利用区域气候模式 (NCC_RegCM1.0) 对青藏高原前冬积雪对次年夏季中国降水的影响进行了数值模拟研究, 所得结果与实际观测的积雪和降水的关系较为吻合, 即长江流域、 新疆地区夏季多雨, 华北和华南少雨, 这与我国最近二十年来维持的 “南涝北旱” 雨型较为一致。因此, 可以认为青藏高原冬季多雪, 是引起中国东部夏季降水出现 “南涝北旱” 的一个重要原因。本文揭示了青藏高原冬季积雪影响我国夏季降水的可能物理机制。青藏高原冬季多雪, 会导致青藏高原地面感热热源减弱, 这种热源的减弱在冬季导致冬季风偏强, 可以影响到我国华南、 西南及孟加拉湾地区。同时, 由于高原热源的减弱可持续到夏季, 成为东亚夏季风和南亚夏季风减弱的一个原因。在积雪初期, 地面反射通量的增加起了主要作用; 在积雪融化后, “湿土壤” 在延长高原积雪对天气气候的影响过程中起了重要作用。初期的反射通量增加减少了太阳辐射的吸收、 融雪时的融化吸热, 以及后期的湿土壤与大气的长期相互作用, 作为异常冷源, 减弱了春夏季高原热源, 是高原冬季积雪影响夏季风并进而影响我国夏季降水的主要机理。本文的模拟结果表明, 青藏高原冬季积雪的显著影响时效可以一直持续到6月份。

    Abstract:

    The influence of snow depth over the Tibetan Plateau (TP) in the preceding winter on rainfall in the following summer in China is simulated by the regional climate model (NCC_RegCM1.0). The simulation results are consistent with the relation of observed snow depth and rainfall, namely, more rainfall occurs in the Yangtze River valley, less rainfall in South China and North China. The results accord with the pattern of “southern flood and northern drought” in China in recent 20 years. So more snow in the TP in winter is one important reason causing “southern flood and northern drought” in summer in China.  The paper reveals the possible physical mechanism of the impact of winter snow over TP on summer rainfall in China. The more the snow over the TP, the weaker the sensible heat source is, which results in stronger winter monsoon in winter, and its effect can reach South China, Southwest China and the Bay of Bengal. At the same time, weaker heat source of the TP can last to summer, which is a reason for the weakening of East Asian and South Asian summer monsoon. In the early stage of snow, the increasing of surface reflected flux is dominant; after snow has melted, “Moist Soil” contributes to prolonging the influence process of snow on weather and climate. The reduction of absorbed solar radiation due to the increased reflected flux, the increase of absorbed heat as snow melts, and the long-term interaction between moist soil and atmosphere weaken the heat source of the TP, which are the main impacting mechanism of winter snow over the TP on monsoon and rainfall distribution in China. The simulation results show that the distinct effect time of snow over the TP can persist to June.

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朱玉祥,丁一汇,刘海文.青藏高原冬季积雪影响我国夏季降水的模拟研究.大气科学,2009,33(5):903~915 ZHU Yuxiang, DING Yihui, LIU Haiwen. Simulation of the Influence of Winter Snow Depth over the Tibetan Plateau on Summer Rainfall in China. Chinese Journal of Atmospheric Sciences (in Chinese),2009,33(5):903~915

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  • 在线发布日期: 2011-12-06
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