A Typhoon Observed with the MU Radar

Abstract

During the passage of Typhoon 8719 a 60-h continuous observation was made of the troposphere and the lower stratosphere with the MU (middle and upper atmosphere) radar. Height profiles of the wind velocity vector were measured every 2.5 min with a height resolution of 150 m. The typhoon struck Japan's main island on 17 October 1987, and passed within 100 km of the MU radar. A clear turning of the wind velocity associated with the typhoon was observed up to a height of around 18 km, while short-period wind fluctuations showed strong effects associated with the typhoon up to 24 km. Prominent waves with vertical wavelength of 2–4 km and apparent period of ∼10 h were found throughout the observation period. The vertical hodograph analysis revealed that these waves propagate both upward and downward from around the layer of a temperature inversion, suggesting the generation of these waves from that layer.