太湖的风效应

WIND EFFECT OF TATHU LAKE

本文分析了太湖湖区风的特征;论述了气流流经湖面后发生的加速现象并估算了加速数值;用滤去大尺度流场的方法,定量的计算了湖陆风向频率和湖陆风速。

The wind characteristics of Taihu Lake region are analyzed. The annual and monthly mean wind speed is 0.5-0.6m/sec greater on lake than that on lake shores, The wind at Dongshan and Xishan( Islands ) , is l,2-1.3m/sec greater than that over the land 10 km and more far from the shore . The acceleration of air-cufrent blowing from land surface to lake surface is est imated.This is one of the wind effects of Taihu Lake. The acceleration value averages 0.2m/sec on Sw and NE lake shores, 0.4m/sec on SE and NW lake shores. Land-lake breeze is another kind of lake wind effect. The wind direction frequency and wind speed of land-lake breeze are estimated quantitatively by using a method of eliminating the influences on air-flow field of large-scale and local environment of small-scale. The duration of lake breeze roughly is 7-9h. The times of the land-lake breeze alternation are at 9-10 and 17-18 o'clock on SE/NW lake shores, at 10-11 and 18-19 o'clock on SW/NE lake shores. The land-lake breeze has the largest wind direction frequency of annual mean 18-21% on SW/NE lake shores, 10-11% on SE/NW lake shores. On an annual average, the largest lake breeze is 1.06 m/sec at 14 o'clock and the land breeze is only≤0.58 m/sec. The angles between the annual mean wind direction of land-lake breeze and their normal line of the lake shores usually are less than 30°.