뇌우에 의한 돌풍사례 분석

Abstract

ABSTRACT

A study on the GUST with thunderstorm

In recent years, South Korea has often witnessed damages by gusts caused by thunderstorms in summer. The Korea Meteorological Administration defines that a gust happens when the maximum instantaneous wind velocity is 10m/s or more and draws up hourly observation reports. When a cumulonimbus develops due to an ascending current and reaches the height of 12∼16km, the temperature of the cloud top drops and a lightening happens, which causes a gust accompanied by a thunderstorm and further regional meteorological damage. It's difficult to predict a regional gust with the meso-scale prediction model at the administration. Thus this study set out to analyze the damage cases by a gust accompanied by a thunderstorm and to make a contribution to the prediction and understanding of a gust by a thunderstorm. A gust by a thunderstorm happens where potential equivalent temperature converges or is higher than the surrounding areas. The convergence area of potential equivalent temperature matches the track of thunderstorm cells. The Kimje gust took place where high potential equivalent temperature converged, and the Jangsu gust did as the area of high potential equivalent temperature approached. There should be a good amount of vapor supply with the moisture flux converging at the bottom layer in order to bring instability. In addition, it should collide into a dry and cold atmosphere at 700hPa. The moving track at the center of the low dew point spread corresponds to that of a gust.

That is, a gust by a thunderstorm moves along the areas where potential equivalent temperature is high on the ground and the regions containing lots of vapor. The time the power of a thunderstorm is maintained depends on the influx of hot and humid air by a warm flow according to the veering of wind directions and the influx of dry and cold air at 700hPa.