FPEC特集号論文
The Characteristics of Upslope Wind in the Shikoku Mountain Area
2005 年 60 巻 5 号 p. 729-732
詳細
2005 年 60 巻 5 号 p. 729-732
The development of an upslope wind during clear, calm daytimes is investigated in two kinds of valleys located in the Shikoku mountain area. The study consists of slope wind observations and vertical atmospheric soundings using a tethered balloon system. Observations were carried out during the summers of 2002 and 2003.
In the valley, which is wide and with gentle inclination, the upslope wind is controlled by the stable atmospheric layer. It is apparent that the upslope wind arises by means of two steps. In the first step, a weak upslope wind starts to blow gradually under the stable atmospheric layer soon after sunrise. The velocity is less than 1.0m/s. In the second step, the height of the stable layer becomes lower from the top and the synoptic wind entrained inside the valley and it accelerates upslope wind. The velocity of upslope wind becomes higher to reach the range of 0.8 to 2.2m/s and the wind direction approaches to that of the synoptic wind.
In the valley, which is narrow and with steep inclination, the upslope wind is affected constantly by the mountain and valley wind system. Because a stable atmospheric layer is not formed inside the steep valley, it seems difficult to develop a pure upslope wind system.
