Long-Term Mean Vertical Wind Observed by the Chung-Li VHF Radar

• Main Author: Jenn-Shyong Chen
• Format: Article
• Language: English
• Published: Chinese Geoscience Union 2006-01-01
• Series: Terrestrial, Atmospheric and Oceanic Sciences
• Subjects: Vertical wind bias; Chung-Li VHF radar; Jet stream; Gravity wave
• Online Access: http://tao.cgu.org.tw/images/attachments/v171p317.pdf

Plenty of observations using VHF/UHF radars worldwide have shown that long-term average vertical winds are downward in the middle troposphere and slightly upward in the lower stratosphere. The Chung-Li VHF radar (121.1°E, 24.9°N), however, hasn’t yet given any report on this issue; in this note we present such observations. Monthly averages show that in the wintertime (from November to February) the vertical velocities were biased to negative values below the jet-stream wind maximum and had magnitudes in excess of 0.5 m s-1 sometimes, which is larger than most other radar observations. In the warm period, however, the vertical velocities were mostly close to zero. In addition, wavelike structures in the profiles of vertical velocities were observed in the lower stratosphere and in the troposphere, respectively, in the wintertime and in two months of the warm period. Many of the vertical velocity profiles presented here are similar to previous observations made with other VHF radars.