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.