摘要
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.
In this paper,the impact and mechanism of snow cover and frozen soil in the Tibetan Plateau on the summer precipitation in China was simulated by using the RegCM3 model.It is revealed that the RegCM3 model can well simulate the impact of frozen depth of soil under different snow cover in the Tibetan Plateau on the summer precipitation in China.Different allocation of melting snow cover and thawing frozen soil in the Tibetan Plateau will result in difference in soil humidity,and then in the processes of phase change and energy absorbed by snow cover and frozen soil.Melting snow cover and thawing frozen soil will cause the surface sensible heat of deep frozen soil higher than that of thin frozen soil in abundant snow years,and then the ascending motion is stronger and the South Asia high and West Pacific Subtropical high both is enhanced.A convergence band will form in the Yangtze River valley,so the summer precipitation of deep frozen soil years is more than that of thin frozen soil years in the Yangtze River valley and central Northwest China,but less in Northeast China,North China,South China,and most Southwest China.When the snow cover is little,the water content of soil is depended on ice content,so the soil humidity of deep frozen soil will be higher than that of thin frozen soil.Therefore,the surface sensible heat in the Tibetan Plateau is weak in deep frozen soil years and the ascending motion is weak too.Both the South Asia high and West Pacific Subtropical high is weak,which will result in the summer precipitation of deep frozen soil year more than that of thin frozen soil years in Northeast China,North China,southern Southwest China,western Inner Mongolia and Xinjiang,but less in the Yangtze River valley and north of South China.
出处
《冰川冻土》
CSCD
北大核心
2011年第2期254-260,共7页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(40705031)
国家重点基础研究发展计划(973计划)项目(2007CB411505)
国家公益性行业专项(GYHY200806005)资助
关键词
高原
积雪
冻土
夏季降水
Tibetan Plateau
snow cover
frozen soil
summer precipitation
