贵州省雾的气候特征研究

利用1961—2004年贵州省84个观测站的天气现象和能见度资料以及9个代表站的地温、气温和相对湿度资料较全面地分析了贵州省雾的空间、时间分布特征。分析表明贵州省雾的空间分布并不具有很强的规律性,全省年平均雾日数为29.9天,在60天以上的地区比较分散,主要分布在东部、西部边缘及中部地势较高处,年平均雾日数大于100天的有3个站,以毕节地区的大方县为全省之最,有170天。贵州省雾的时间分布具有明显的季节和日变化。尽管每月都有雾出现,但主要集中在冬半年(10月至次年2月),雾最少时段在5—7月,一天当中早08时发生雾的频率最高;雾的年际变化分析表明贵州省84站平均雾日数呈明显减少趋势,平均每年减少0.06日。进一步对贵州省9个代表站的气象条件进行初步的统计分析,显示冬季最低气温的逐年升高,年平均每日地温与气温之差、日最高气温与最低气温之差的降低以及年平均相对湿度的减少是造成年平均雾日数呈减少趋势的原因。

Climatology of Fog in Guizhou Province

The observed daily meteorological phenomena and visibility of 84 stations from 1961 to 2004 are used to study the special and temporal character of fog climatology in Guizhou Province. Also daily ground and air temperature, relative humidity of 9 selected sample stations are also included. The mean annual geographical distribution of fog frequency in Guizhou is randomly. The average annual fog frequency is 29.9 days. The stations with more than 60 mean annual fog day frequency scatter in the east, west and central area of Guizhou with relatively high altitude. There are 3 stations whose annual fog frequencies exceed 100 days. The highest fog frequency of Guizhou is 170 days in Dafang county of Bijie. The seasonal and diurnal variations of fog occurrence are obviously. Although fog may occur in each season, but most of fog occur in cold season (from October to February) and less from May to July. On the diurnal time scale, fog events occur mainly on 0800 of local time. The mean annual fog frequency show a decreasing trend with a rate of 0.06 day per year. Further statistical study based on meteorological data show that the decrease of mean fog occurrence might be caused by several climate changed issues: a rising trend of the mean daily lowest temperature in winter, a decreasing trends in the difference between ground and surface air temperature,the annual mean difference between higest and lowest surface air temperature,and the annual mean surface relative humidity.