[M-IS11] Mountain Science

[MIS11-P03] Formation process of Cold-Air-Pool with thick layer in valleys with large elevation differences

*Hirokatsu Kaneko¹, Motoshi Nishimura², Akihiko SASAKI³, Koichi Sakakibara⁴, Keisuke Suzuki⁵ (1.Graduate School of Science and Technology, Shinshu University, 2.National Institute of Polar Research, 3.Kokushikan University, 4.Shinshu University, 5.Research Center for Mountain Environment, Shinshu University)

Keywords:Cold-Air-Pool, Mountain Meteorology, Mountain Science

In basins and valleys surrounded by mountains, radiative cooling causes cold air to accumulate at the valley floor, creating a cold air pool where the temperature at the valley floor is lower than the upper levels. In the Kamikochi region of the Northern Alps, narrow valleys with an elevation difference of more than 1500 m provide an ideal environment for the formation of Cold-Air-Pools. In this study, temperature loggers were installed at 14 points on the southern slope of Mt. Myojindake in Kamikochi, and temperatures were recorded hourly at 1550 to 2300 m on the same slope. From the observation results, hourly temperature-altitude vertical profiles were created, and the thickness of the Cold-Air-Pool layer was determined.
In the case of a thick Cold-Air-Pool layer, temperature inversions began after sunset at the bottom (valley floor) and top (mountainside) of the slope, and these inversions combined to make the Cold-Air-Pool layer thicker. This is influenced by the slope topography.