新疆库尔勒地区秋季下平流层重力波特性

Gravity wave characteristics in the lower stratosphere over Korla,Xinjiang

利用2011年秋季无线电探空数据,采用矢端曲线法首次分析了新疆库尔勒地区下平流层重力波特征参量,得到36组准单色重力波的结果.结果统计显示:库尔勒秋季下平流层重力波垂直波长、水平波长平均值分别为2.8km和580km,固有频率平均值为1.74f.垂直传播方向以上传为主,约占78%,其中下传重力波水平波长较短,固有频率较高.水平传播方向以西北和东南为主,各占1/3,其中上传(下传)重力波水平传播方向以西北(东南)居多,这与热带低纬站点和其他中纬站点观测结果不同.与其他站点比较,库尔勒地区ω^/f最小,中高纬地区水平波长、垂直波长随纬度增加大致有减小的趋势,库尔勒地区偏离这一趋势,波长偏大.

The gravity wave parameters in the lower stratosphere over Korla are studied for the first time based on the high vertical resolution radiosonde data in the autumn of 2011.A total of 36 quasi-monochromatic gravity waves were extracted.The result shows that the mean values of vertical wavelengths,horizontal wavelengths and intrinsic frequencies are 2.8 km,580 km and 1.74 f respectively.GWs propagating upward in the vertical direction are with an occurrence of 78%.Compared with the upward propagating GWs,the horizontal wavelengths of downward propagating GWs are shorter,and intrinsic frequencies are higher.The mean horizontal propagation directions of the gravity waves were mainly northwest(upward)and southeast(downward),both accounting for 1/3,which is different from the results over low-latitude and other mid-latitude stations.The ratioω^/f is smallest over Korla compared with other sites.And there is a trend that horizontal(vertical)wavelength decreases with increasing latitude in mid and high latitudes,but the relatively longer wavelength over Korla deviates from this trend.