武汉上空惯性重力波活动

利用武汉中心气象台(30.5°N,114.4°E)无线电探空仪在2001年1月到2003年12月之间的观测数据,研究了武汉上空1-9km和14-25km高度范围内惯性重力波参数的变化特征.数据分析结果表明,重力波活动存在明显的季节变化,冬季较频繁,夏季活动较弱,与急流强度的季节变化一致,这意味着重力波的激发与背景风密切相关.矢端曲线分析显示1-9km范围内能量向上传播和向下传播的波的比例大致相同,而14-25km范围内绝大部分波能量向上传播,这与最大急流强度的高度相对应;进一步分析表明,夏天14-25km范围内波几乎全向上传播,而冬天则有相当一部分波向下传播,这可能是反射引起的.重力波的本征频率集中在1-3倍的惯性频率之间,水平波长约数百公里;1-9 km范围内垂直波长集中在3-3.5 km,14-25 km高度内则集中在4.5-5.5 km.

Gravity Wave Activities in the Lower Atmosphere Over Wuhan, China

Radiosonde observations provided by Wuhan Center Station of Meteorology （30.5° N, 114.4° E） between January 2001 and December 2003 are used to study the spatial and temporal variations in gravity wave activities in the lower atmosphere over Wuhan, China. Time series of horizontal kinetic energy show an obvious seasonal variation with the maximum in winter when jet is strongest and the mimimum in summer when there doesn＇t exist the jet. Using a hodograph analysis, it is found that about 46.4% of the waves are propagating upward in the height range of 1-9 km, while roughly 73.8% of the waves are propagating upward in 14-25 km, in agreement with the assumption that gravity waves are generated by the jet stream near 11 km. Further examination reveals that within the height range of 14-25 km gravity waves are mostly propagating upward in summer while quite a portion of gravity waves propagate downward in winter, which might be caused by reflection. The intrinsic frequencies are mostly 1-3 times the inertial frequency. Horizontal wavelengths of several hundred kilometers are inferred. The vertical wave lengths are centered on 3-3.5 km during 1-9km, but 4.5-5.5km during 14-25km.