Study of Local Climate in Mountainous District by Airborne MSS Thermal IR data: Development of Cold Air Lakes

Abstract

The authors investigated the distribution of the surface temperature of Unzen volcano and development of cold air lakes at Unzen hot-spring resort and in its vicinity, west of Mt.Fugendake of Shimabara peninsula, Nagasaki prefecture by airborne MSS thermal IR data obtained early morning on March 16, 1982.
Meteorological data obtained at Kinugasayama (846 m) and Unzendake (677m) meteorogical station showed temperrature inversion of the study area. Surface temperature of the summits and convex upward mountainsides was higher than that of the valley and basin floors and concave upward mountainsides. The result was confirmed by temperature inversion indicated by the meteorological data.
Cold air was produced mainly not only on the basin foor but also on the surface of the gentle concave upward and straight slopes of the mountain. Cold surfaces were also recognized on the valley plains and gentle slopes upstrem from barriers such as hills and narrow valley walls.
Surface temperature of the bare soil or thin vagetated surface was colder than that of vegetated or forested surfaces. Therefore, the forest makes no contribution to the production of the cold air of the mountain.