连云港市沿海大雾多发期的特征分析

Analysis on Characteristics of Multiple Period of Coastal Fog in Lianyungang

利用1973～2003年大雾气象资料,分析了连云港市沿海大雾的气候特征及大雾多发期的特征。结果表明,连云港市沿海大雾存在明显的年际和年代际变化,大雾呈现逐年增长趋势,且20世纪70年代大雾最少,90年代最多;大雾月变化呈双峰曲线,主要集中在3～6月和11月～次年1月;一天中大雾多发生20:00～次日08:00,其中以04:00～08:00发生频率最高,消散时间主要集中在12:00以前,其中以08:00～10:00最多;大雾持续的时间有长有短,大多数大雾都在8 h以内散尽消失,其中大雾持续2 h的比例最高;从连续性特征看,无论哪个多发期,持续2 d的连续性大雾最多,3 d次之;不同季节出现大雾时的风向风速也有所不同,11月～次年1月大雾时的风速90%以上均在3 m/s以下,风向以静风最多,占30.3%,其次是第3象限风向(SSW-W);而3～6月份,大雾时的风速明显偏大,且第1象限风向(NNE-E)最多,占52.2%。

The meteorological data of heavy fog from 1973 to 2003 was used to analyze the climate characteristics of Lianyungang coastal fog and the characteristics of multiple period of fog.The results indicated that there was obvious interannual and interdecadal changes of Lianyungang coastal fog,moreover,heavy fog showed increasing trend,heavy fog of 1970s was the least,1990s was the most;monthly variation of heavy fog presented bimodal curve and mainly concentrated in March-June and November-January of the following year.The fog occurred frequently from 20：00 to 08：00 of the following day,of which 04：00-08：00 was the highest frequency period,dissipation period were mainly concentrated before 12：00,especially during 08：00-10：00.The duration of heavy fog were long or short,most heavy fog disappeared within 2 h.Seen from the characteristics of continuity,among all multiple periods,the continuation of 2 d was the most,followed by 3 d.The wind direction and speed of different seasons were also different at the time of heavy fog,moreover,more than 90% of wind speed was less than 3 m/s during December-January of the following year at the time of heavy fog,calm wind occupied 30.3% at most,followed by the third quadrant wind（SSW-W）;however,during March-June,the wind speed was distinctly bigger,and the first quadrant wind（NNE-E）occupied 52.2% at most.