粤西沿海海雾天气气候特征及微物理结构研究

利用粤西12个测站2000-2010年常规气象资料及2010年3月湛江东海岛一次海雾过程观测数据，分析了粤西沿海海雾发生的天气气候特征以及湛江东海岛海雾的微物理特征。结果表明：粤西沿海年均雾日数呈西部（17．8d·a^-1）〉东部（7．7d·a^-2）〉中部（3．5d·a^-1）的特点；年际变化差异明显，除2008年外呈逐步升高趋势；年雾日数冬、春季多，夏、秋季少；一天中海雾大部分出现在02：00—08：00，这一时段雾生成的平均概率为50．8％；最多持续时间在1-3d内。海雾生成的综合气象条件主要为：气温15．025．0℃、3小时变压-3．5-2．5hPa、温度露点差0．0-2．0℃、多发风向为NNE-ESE或静风，风速≤7m·s^-1。成雾的天气形势可以分为高压型、低槽型、冷锋型、静止锋型和鞍型或均压场型5类。雾过程中各阶段能见度变化及雾滴谱分布差异较大，平均雾滴谱分布符合指数递减规律，谱型大体上呈“单峰”结构，整个滴谱明显偏向小滴一端，雾滴谱径主要出现在2～10μm。

Analysis on the Climatic and Microphysical Characteristics of Sea Fog over the Coast of West Guangdong

By using the surface observation data at 12 stations in the coast of West Guangdong from 2000 to 2010 and the sea fog observation data on Donghai Island in Zhanjiang during March 2010,the climatic and microphysical characteristics of coastal fog are statistically analyzed.Results show that the fog day number has a variation tendency in West Guangdong,i.e.western(17.8 d ? a^-1)>eastern(7.7 d ? a^-1 )> central (3.5 d ? a^-1 ).The annual change is significantly different and has a gradually rising trend during 2000—2010 except the 2008.There are more fog days in winter and spring,and less in summer and autumn. Generally most fog events in a certain day occur between 02:00 and 08:00 BT,and have an average probability of 50.8%.The duration of sea fog process is mostly between 1 and 3 days.The comprehensive weather conditions of fog generation mainly are that wind speed is≤7 m ? s^-1 and wind directions are NNE—ESE and calm wind,and the appropriate air temperature is between 15.0 and 25.0°C,and the 3 h pressure change is in an interval of—3.5—2.5 hPa,and depression of the dew point continuously approaches to 0.0—2.0°C.The synoptic situations favorable for the fog formation and development on the Leizhou Peninsula can be roughly divided into five classes;high pressure system,low trough system,cold front, stationary front,saddle type pressure field or isobaric field.The droplet size distribution is quite different during fog process.The average droplet size distribution is generally consistent with exponential distribution, and the type of the average droplet size distribution is similar to the "single peak" structure.Drops significantly bias the small end of the spectrum,and the droplet spectrum diameters mainly appear in 2 - 10μm.