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利用RegCM3模式,通过计算青藏高原不同积雪、冻土年的气候状况,分析了高原地区不同积雪状况下土壤冻结差异对中国夏季降水的影响及其机理.结果表明:RegCM3模式能够较好的模拟不同积雪状态下高原土壤冻结差异对中国夏季降水的影响.多雪年当高原土壤冻结较厚时,在长江流域和西北地区中部降水偏多,东北地区、华北地区、华南地区、西南地区大部降水偏少;而少雪年冻结较厚时,东北地区、华北地区和西南地区南部、内蒙古西部和新疆西部降水偏多,长江流域、华南地区北部降水偏少.造成这种差异的原因可能是积雪融化和冻土解冻不同配置型对夏季高原土壤湿度的不同影响,加上相变过程吸收能量的差异.冻结较厚时,地表感热偏大,高原地区上升运动偏强,南亚高压和西太副高均偏强,850hPa水平风场差值在长江流域形成一条气流辐合带,导致长江流域降水偏多,而华北、华南地区降水偏少;而少雪年冻结较厚时土壤含水量偏高,加上吸收相变潜热,青藏高原地表感热偏低,南亚高压和西太副高均偏弱,长江以北有明显的北风距平,使得北方降水偏多,南方降水偏少.
RegCM3 model was used to analyze the effect of different soil freezing on the summer precipitation in China and its mechanism by calculating the climatic conditions in different years of snow cover and permafrost over the Qinghai-Tibet Plateau.The results show that the RegCM3 model is better Simulating the effect of plateau soil freezing difference on summer precipitation in China under different snow cover conditions.When the plateau soil freezing was thick in the snowy season, precipitation tends to be more in the middle reaches of the Yangtze River valley and the northwestern China than in the Northeast China, North China, South China and Southwest China In most of the cases, the precipitation is less than that in the northeastern China, the northern part of North China, the southwest part of Inner Mongolia, the western part of Inner Mongolia and the western part of Xinjiang, and the less precipitation in the northern part of the Yangtze River and South China. Which may be the different effects of different types of thawing on the soil moisture in the summer and the differences in the energy absorbed during the phase transition.When the soil was frozen, the sensible heat of the surface was large and the upward movement in the plateau was stronger. Both the high pressure and the West Pacific subtropical high are stronger and the difference of the wind field at 850 hPa forms a convergence zone of the airflow in the Yangtze River basin, resulting in precipitation partiality in the Yangtze River Basin , While the precipitation in North China and South China is less than normal. However, when the freezing years are relatively small, the soil moisture content is relatively high, and the latent heat of absorption is low, the surface sensible heat of the Qinghai-Tibet Plateau is low, the South Asia High and West Pacific subtropical are weak, There is obvious north wind anomaly to the north of the Yangtze River, leading to more precipitation in the north and less precipitation in the south.