OUTBREAK MECHANISM IDENTIFICATION OF LINE-SHAPED CONVECTIVE SYSTEMS USING LES FOCUSED ON POTENTIAL TEMPERATURE FLUCTUATION BY MOUNTAIN WAVES

Abstract

 Recent years, there is a lot of disasters from line-shaped convective systems. The mechanism of outbreaks has not been clarified, and it is difficult to predict it. Necessity and contingency factors were rarely discussed separate. In this study, numerical experiments were conducted using LES(Large-eddy-simulation), which can exactly calculate turbulence and evaluate necessity and contingency in the presence of contingency, in order to distinguish each factor and to elucidate the detailed mechanism of oubreak. The result indicates that mountain waves caused by the topography of Awaji Island form a low-temperature region in the southern part of Mt. Rokko, contributing to the rise of other warm air masses. In addition, an ensemble experiment with random noise in the initial value of potential temperature suggested the existence of an influence of contingency factors on occurrence.