[A-AS08] Multiple scale structure and their interactions in Asian monsoon system

[AAS08-P03] Environmental conditions of atmospheric fronts appearing in the rainy season in Japan

*Maki Miyamoto¹, Tomohito J. Yamada¹ (1.Hokkaido University)

Keywords:identifying fronts, weather map, density interface

In the mid-latitudes, much rainfall is brought by atmospheric fronts. They are defined as a density interface, mainly due to a large horizontal gradient of temperature. In western Japan, they are characterized by a discontinuity of water vapor associated with the southwesterly flow such as Asian monsoon.Torrential rainfall following fronts causes serious damages over those regions in the rainy season. To clarify a mechanism of rainfall induced by fronts, identifying fronts in meteorological fields is a significant issue. There are two approaches for extracting fronts; one is using meteorological elements such as temperature and the other is manual detection by forecasters. We should examine those methods for detecting fronts because a discontinuity of density couldn’t be directly observed. In this study, we made a gridded dataset of fronts by extracting them using RGB values from weather maps published by Japan Meteorological Agency from June to October, 1978 to 2020. It would be utilized to reveal a structure of atmospheric fronts and distribution of rainfall around fronts.