Vertical wind disturbances in the troposphere and lower stratosphere observed by the MU radar

Abstract

First, it is shown through spectral and lag-correlation analyses that there are several common features in three observation periods when the VWDs appeared: large power in the vertical wind fluctuations exists below a height of ~20 km and is distributed largely at lower frequencies. Second, using eight sets of the MU radar data, the relationship between vertical wind activity and horizontal wind near the surface is examined in order to identify the source of the VWDs. The activity of the vertical wind is closely related to both direction and strength of the horizontal wind near the surface at Yonago (about 250 km west of Shigaraki). This indicates that the VWDs are due mainly to gravity waves generated by the effect of topography with heights of ~1000 m located between Yonago and Shigaraki. Finally, vertical momentum flux associated with the VWDs is examined. -from Author