Abstract
The Osaka Plain faces with the Ikoma and Kongo Mounts on the east and south. Our preceding study confirmed using 3 dimensional numerical simulations that nocturnal drainages break out on the west-facing slopes of the mounts and flow into the east part of the plain. Purposes of the present study are to examine their occurrence conditions and influences on nocturnal temperature distributions of the part by analyzing such observational data as the AMeDAS data. In addition, occurrence relationships between the nocturnal drainages of the east part and those of the north part and influences of the two on heatisland phenomena in the Osaka Plain are investigated. The result shows that the nocturnal drainages in the east part tend to occur in the condition that daily solar radiation is relatively large and both north-south and east-west components of geostrophic wind are about 5.0m/s.
