Fine Structure of Vertical Motion in the Stratiform Precipitation Region Observed by a YHF Doppler Radar Installed in Sumatra, Indonesia

摘要

Vertical motion W profiles in the stratiform precipitation region of mesoscale cloud clusters were investigated using wind data observed by VHP Doppler radar installed in western Sumatra Island (0.2 deg S, 100.32 deg E). A special mode for W observations was introduced in November 2003, and W data with high accuracy were obtained during most of the period, with fine resolutions of 3 min in time and 150 m in vertical direction. The typical fine structure of W within the nimbostratus in the stratiformprecipitation region was investigated by the case study of 6, 8, and 20 November 2003. In the later 2 or 3 h of the stratiform precipitation period, gentle upward motions with small time and height fluctuations were observed over a several-kilometer height range from the middle to upper troposphere. Values of W were weakly positive (0-40 cm s~(-1)) continuously, with little strong upward motion greater than 40 cm s~(-1)and downward motion.