Vertical wind disturbances in the afternoon of mid‐summer revealed by the MU radar

This paper reports a kind of vertical wind disturbances which appear daily in the afternoon of mid‐summer in the troposphere. A detailed analysis was made of wind data monitored by the MU radar (35°N, 136°E, Shigaraki, Shiga, Japan) for about five days in July 1987 as a typical example. The disturbances propagate upward up to (sometimes over) the tropopause level with a speed of 0.4–1.8 m s−1 as a packet. The timing of generation and propagation suggests that they are convective motions of cumulus clouds generated by solar heating on the ground. A map of cloud‐top height with high horizontal resolution of about 1 km provided by a satellite of NOAA‐9 supports this inference. The structures near the tropopause and spectral characteristics are shown.