商丘雾变化的气候特征及天气分型

依据商丘市8个站1961~2004年雾资料,分析了大雾天气的分布和气候变化特征。结果表明:商丘市雾的地理分布是西部睢县至宁陵一带为多雾区,南部柘城至夏邑一带为少雾区。宁陵出现大雾最多,睢县次之,柘城雾日最少。年际变化总体呈上升趋势。月际变化呈“V”型特征,秋冬季雾最多,夏季最少。雾的日变化一般在下半夜到清晨日出前后形成,05:00~06:00最易生成大雾,雾消时间一般在06:00~12:00,日出后07:00~08:00雾最容易消散。最长连雾日一般出现在11至次年1月,而1月出现最长连雾日的次数最多。雾的持续时间3 h以下的短雾最多,12~24 h的最少,没有超过24 h的长雾,连雾时间最长为23.3 h。年最多雾日,宁陵最多为120 d,柘城最少只有32 d,其余各站在40~77 d之间。商丘市雾发生时的地面天气形势主要有大陆高压型、冷锋前暖区型、均压场型和(低压)倒槽型。

Climate Characteristics and Synoptic Patterns of Fog in Shangqiu

The distribution and the climate characteristics of fog in Shangqiu are analyzed by use of fog data from eight weather stations in Shangqiu from 1961 to 2004.The results indicate that fog days occurred more frequently in the west part such as Suixian and Ningilng than in the south part such as Zhecheng and Xiayi.There was an increasing annual tendency in foggy days and a V-shaped monthly variation feature with the maximum in fall and minimum in summer.The fogs occurred generally in early morning,and dissipated most likely at seven to eight o'clock after sunrise.The duration of fog was mostly less than 3 hours and there was no fog maintaining more than 24 hours.Based on the weather maps from 1999 to 2004,the surface synoptic patterns favorable for foggy days can be classified to four kinds: continental anticyclone,warm zone in front of cold front,uniform pressure field,and low pressure with an inverted trough.