科研之友
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摘要
Observations from a Doppler radar, a wind profiler, and a meteorological tower were used to study the evolution of two thin-line echoes that were observed in the radar reflectivity field over the Kanto Plain of Japan as Typhoon Higos (0221) passed in October 2002. Both thin-line echoes were accompanied by gusty winds and followed by cold airflows, and both passed the field site of the Meteorological Research Institute (MRI) in Tsukuba, Japan. Data from the MRI instrument array and from a surface observation network revealed that the first thin-line echo was Caused by a gust front, and the second thin-line echo was caused by a solitary wave. Although it was demonstrated that the first thin-line echo was due to a gust front, this gust front could not be categorized as a so-called thunderstorm gust front because it had no parent thunderstorm; rather, Doppler radar and wind profiler observations suggested that both relatively strong (similar to 4 m s(-1)) downdrafts and large momentum transported by the downdrafts from aloft (similar to 4 km) to lower levels produced and enhanced near-surface winds behind the gust front. In contrast, the solitary wave associated with the second thin-line echo likely developed as another gust front that generated from an outer rainband to the south of the typhoon center met a stable layer formed by the cold outflow behind the gust front associated with the first thin-line echo. The ducting mechanism that enabled the solitary wave to propagate was also revealed from the wind profiler and radiosonde measurements.
- 出版日期2009-2
- 单位中国气象科学研究院
