Abstract:

Based on wind speed observed data of 73 meteorological stations from 1961 to 2010 in Hebei Province，and combined monthly mean Northern Hemisphere circulation index data issued by National Climate Center and NCEP/NCAR monthly mean reanalysis data, the temporal and spatial distribution of surface wind speed and maximum prevailing wind direction frequency variation as well as the formation cause for wind speed decrease were discussed by using linear trend fitting method. The results show that, the maximum wind speed appeared in the northeast region of Hebei, the second largest wind speed appeared in the east coast and southeast area, and the smaller wind speed appeared in the middle region of Hebei Province. The annual mean wind speed presented descending trend from 1961 to 2010 with a rate of 0.212 m/s each decade. The days with wind speed less than 3.0 m/s increased, but windy days with wind speed greater than 8.0 m/s decreased , and when wind speed ranged from 3.0 to 8.0 m/s, there was no significant variation tendency for windy days. The maximum prevailing wind direction of representative stations was southwest or south, the southerly wind frequency increased by 0.54 day every year on average. The decrease of wind speed in Hebei was mainly related to circulation factors such as westerly index increase, and influence of the urbanization effect.

Key words: wind speed, temporal-spatial distribution, change tendency, formation cause

摘要：

利用1961～2010 年河北省73个地面气象站风观测资料，结合NCEP/NCAR（2.5°×2.5°）月平均再分析资料和国家气候中心下发的环流指数，采用线性趋势拟合方法，分析地面风速的空间分布以及风速和最大主风向风频的时间变化特征，并对风速减小的成因进行探讨。结果表明：空间上风速呈东北西南向带状分布，依次有大、小、大3个风速带。年平均风速呈减小趋势，减小速率为0.207 m·s-1/10 a；3.0 m/s以下的风速日数呈明显增加趋势，8.0 m/s以上的日数呈显著减小趋势，3.0～8.0 m/s风速的日数没有明显变化趋势。代表站最大主风向为偏南风，最大主风向风频平均每年增加0.54 d。风速的减小与1980年代以后影响我国的环流经向度减小、西风指数增加有关，也与城市化效应的影响有关。

关键词: 地面风, 时空分布, 变化特征, 成因探讨