Characteristic Analysis on Mountain-Valley Wind in Deep Valley

Abstract

Taking the actual measured data and the simulating result from WRF(Weather Research & Forecasting)/CALMET numerical model, analysing the air flow field in the industrial park in some valley of northern Sichuan Province, it shows that the valley has the mountain-valley wind formed by the topographical thermodynamic effects, and the characters of mountain-valley wind change with season. In January in winter, the valley wind appears at 8:30 in the morning, and prevails after 2 hours transition. The wind strength (wind velocity, circulation height and thickness) is the strongest at about 14:00. The valley wind lasts about 7 hours, and then changes into the mountain wind at 17:30. After 3.5 hours, at 21:00, the mountain wind prevails and lasts 11.5 hours to 8:30 in the next morning. In July in summer, the valley wind appears at 6:30 in the morning. Through 1.5 hours transition, the valley wind prevails at 8:00 and becomes the strongest at 14:00. The valley wind lasts about 10.5 hours and begins to change into the mountain wind at 19:00 in 3 hours. From 22:00 to 6:30 in the next morning, the slope wind prevails and lasts about 8.5 hours. In winter, the thickness for valley wind is bout 100~300m with the average wind speed 1.5~4.0m/s and the thickness for mountain wind is 50~200m with average wind speed 1.5~3.0m/s and circulating sphere height 600~800m. In summer, the valley wind thickness is about 200~500m with average wind speed 2.0~7.0m/s and the mountain wind thickness is about 150~400m with average wind speed 1.5~5m/s and circulation layer height 600~800m. Since the orientation of mountains is different at the both sides of valley, the time and the strength for the mountains receiving the solar radiation are different, the regulation and the characters for mountain-valley wind appearing and disappearing are also different.