张家口地区风特征分析

为了揭示张家口地区风向风速时空分布特征及主要变化趋势，为该地区合理利用风资源、减轻风灾提供参考，利用1960—2013年张家口地区14个气象站风速风向观测资料，借助数理统计、线性拟合、气候倾向率等方法，对该区域的风特征进行了统计分析。结果表明，张家口地区年均风速坝上地区为3.6~4.1m/s，大于坝下地区的1.8~3.0m/s。年均风速变化总体呈减小趋势，54年间坝上与坝下地区分别减小了2.21m/s与0.92m/s，最大减小幅度均出现在20世纪70年代。年均风速呈“春季大、夏季小”的分布类型，平均风速最大、最小值分别出现在4月和8月。年均风速冬季减小速率最大，夏季最小。风速日变化坝上地区13—15时、坝下地区15时左右达到最大，凌晨5—7时风速最小，一天中平均风速上午的增长率与午后的下降率，坝上地区均大于坝下地区。坝上四县年均大风日数为48.5天/县，坝下为31.8天/县，大风日高值时段发生在1963—1974年间，坝上与坝下地区大风日数分别以9.4d/10a与7.1d/10a的速率减少。张家口地区全年以NW、偏北和偏西风向为主，市区、各县春季和冬季主导风向一致，夏季和秋季主导风向一致；进入夏季，随着暖湿气流的增强，张家口市偏南和偏东风出现频率有所增加。

Characteristics Analysis of Wind in Zhangjiakou

In order to reveal the main characteristics of spatial-temporal distribution and change trend, and to provide the reference for rational utilization of resources and reduction of disaster in Zhangjiakou region, the wind observation data from the 14 ground meteorological stations in Zhangjiakou region nearly 54 years from 1960 to 2013 were statistically analyzed by mathematical statistics, linear fitting, climate trend rate method and so on. The results showed that: The annual average wind speed in of Zhangjiakou was 3.6-4.1 m/s, larger than that of 1.8-3 m/s in Baxia area . The annual average wind speed showed declining tendency,with the reduction of 2.21 m /s in Bashang area and 0.92 m / s in Baxia area during the 54 years. The maximum decrease appeared in 70"s of last century. The annual average wind speed showed the type of seasonal distribution of large, summer small", and the maximum and minimum of average wind velocity occurred respectively in April and August. The annual average wind speed decreased by the maximum rate in winter and the minimum in summer. The wind speed reached the maximum from 13:00 to 15:00 in Bashang area and about 15:00 in Baxia area and the smallest at 05:00- 07:00. The rate of growth and decline of wind speed in Bashang were greater than that in Baxia . The gale days reacded 48.5d/ County in Bashang and 31.8d/ County in Baxia. The peak occurred between 1963 and 1974 and were reducing at the tendency of 9.4 d /10 in Bashang and 7.1 d /10 a in Baxia. The prevalent winds were NW, N and W in Zhangjiakou region throughout the year, and the dominant wind is respectively consistent in spring and winter, in summer and autumn. In the summer, with the enhancement of warm air, the Southerly and Easterly wind increased .