新疆地区25a地面风场特征分析

Analysis of Surface Wind Field Characteristics in the Last 25 Years in Xinjiang,China

地面风除了受大范围环流影响外,还受地形影响较大。新疆既有大的盆地,又有高山垭口,造就了特殊的新疆地面风场。利用新疆54个气象站1980—2004年,每日4个时次的地面风资料,分析了该地区地面风场的长期特征,并进行经验正交函数分解。研究表明,新疆长期地面风场北疆、东疆和南疆有显著差别,主要表现在风向的转变,即北疆总体表现为西北风,南疆表现为偏东风,东疆表现为由西北风向偏东风转换的反气旋性弯曲气流;新疆经向风的长期变化表现为南风距平加强,而纬向风则表现为东风距平加强;经向风在整个时间序列上有3～5a的短期变化,而纬向风在整个时间序列上有3～6a的短期变化,且都表现为随时间延续周期变长;经向风南风距平增大趋势的最大值发生在七角井,而北风距平增大趋势的最大值则在阿拉山口。纬向风西风距平增大趋势的最大值在七角井,东风距平增大趋势的最大值位于安德河;EOF分析表明,第一特征向量的贡献达到87.5%,而第一特征向量对应的时间系数的距平值以1987年和1999年为界,表现为"正负正"的趋势。

In addition to be impacted by large-scale atmosphere circulation,the surface wind is also influenced by regional terrain.In Xinjiang,there are large basins,big mountains and canyons,so surface wind field is special there.In this paper,based on Xinjiang surface wind field data from 1980 to 2004,long-term surface wind field characteristics of this region are analyzed,and the empirical orthogonal function decomposition to the data is made.Results show that there are significant differences between surface wind field in northern,eastern and southern Xinjiang,especially in wind direction changes： northwest wind for northern Xinjiang,east wind for southern Xinjiang,airflow conversion of anticyclonic from northwest wind to east wind for eastern Xinjiang.Analysis of long-term change of meridional wind in Xinjiang shows that the meridional wind is manifested in increase of southerly wind anomalies,while the zonal wind is manifested in weakening of westerly wind anomalies.Meridional wind change has 3—5 years short-term change cycle in the whole time series,and zonal wind change has 3—6 years cycle,and they all show a phenomenon of continuation of their cycles growth over the time lengthen.The maximum value of the meridional southerly wind anomalies occurs at Qijiaojing,while the maximum value of meridional northerly wind anomalies occurs at Alashankou.The maximum value of zonal wind westerly wind anomalies is also at Qijiaojing,while the maximum value of zonal easterly wind anomalies is at Andehe.EOF analysis shows that the variance contribution of the first mode is 87.5%,while the anomaly values of temporal coefficient of the first mode showed ＂positive-negative-positive＂ trend.