17:15 〜 19:15
[AAS03-P02] 日本の北部と南部で発生する集中豪雨時の湿潤不安定性：2023年7月の事例解析
キーワード：メソ気象学、メソ降水系、集中豪雨、梅雨、環境条件
The environmental conditions for the generation of heavy rainfall during the Baiu season in Japan are characterized with an abundant content of water vapor, nearly saturated humidity, and nearly moist-adiabatic lapse rate. Naka and Takemi (2023, SOLA, hereafter NT23) indicated that the presence of moist absolutely unstable layers (MAULs) explains the occurrence of Baiu-season heavy rainfall events that occurred in Japan in recent years. This study further investigates the environmental properties of heavy rainfall events that occur in contrasting geographical regions in Japan: northern Kyushu (southern Japan) and Tohoku (northern Japan). Heavy rainfall events that occurred in July 2023 are chosen for the present analysis. The environmental conditions in Tohoku are very similar to those found by NT23. The case in Tohoku accompanies the presence of thick MAUL, which well correlates with the precipitation amount. On the other hand, in Kyushu, the characteristics of environmental conditions near the precipitation area are largely different from the cases examined in NT23. The July 2023 case in KYN indicates that there is substantially no presence of MAUL.
The case in Kyushu indicated that the amount of CAPE is significantly larger than that in Tohoku, and much larger than the climatology in Kyushu. This suggests that an important factor affecting the heavy precipitation in Kyushu can be attributed not to MAUL but to CAPE. CAPE for air parcels originated at elevated heights as well as the ground level demonstrates that non-zero CAPE exists deeply from the ground to an altitude above the boundary layer. It is considered that the difference in environmental conditions between the Kyushu and Tohoku regions is resulted from the difference in humidity and instability. The present analysis suggests that there will be different types of precipitation mechanisms: MAUL-driven and convective instability-driven.
The case in Kyushu indicated that the amount of CAPE is significantly larger than that in Tohoku, and much larger than the climatology in Kyushu. This suggests that an important factor affecting the heavy precipitation in Kyushu can be attributed not to MAUL but to CAPE. CAPE for air parcels originated at elevated heights as well as the ground level demonstrates that non-zero CAPE exists deeply from the ground to an altitude above the boundary layer. It is considered that the difference in environmental conditions between the Kyushu and Tohoku regions is resulted from the difference in humidity and instability. The present analysis suggests that there will be different types of precipitation mechanisms: MAUL-driven and convective instability-driven.