四会市灰霾天气的变化特征及影响因子

首先利用四会市气象局观测站1959—2012年的地面气象观测资料,对四会地区灰霾天气历史情况进行总结,由于2000年以前灰霾判别标准不统一,阈值偏低造成2000年以前灰霾天数记录偏少,故选择2000—2012年13年的灰霾变化特征、变化规律,及其影响因素进行分析。结果表明：2000年后四会地区的灰霾日数总体呈上升趋势,尤其是近5年来更加明显;灰霾天气具有明显的季节差异,呈现为冬季〉秋季〉春季〉夏季的特征;绝大多数霾天能见度在5~10 km,为轻微灰霾天气,2007年开始小于5 km的轻度或中度灰霾日数也逐渐增加;连续灰霾天气过程增多,尤其是最近3年,灰霾天气中连续灰霾日已超过1/2,灰霾天气持续时间最长达13 d;灰霾天气受气象要素的影响较显著,较小的风速、较大的相对湿度均有利于霾天气的出现;灰霾一定程度上会减少可记录日照长度;近年来大气污染的日益严重,汽车尾气、工业废气、粉尘等大量排放使污染物浓度增大,也可能是灰霾天气频发的一个原因。

Characteristics of the Variation of Hazy Weather in Sihui City and Associated Influencing Factors

Using the surface meteorological data observed at the Sihui station from 1959 to 2012,this paper summarizes the historical records of local hazy weather. Due to insufficient records of haze resulting from lower thresholds in discriminating haze prior to 2000,this work chooses the data from 2000 to 2012 to study the characteristics and patterns of haze variation and associated factors influencing them. The results are shown as follows. Generally,the number of hazy days has been increasing,more obviously in the past five years. The local hazy weather shows significant seasonal variation,which is most remarkable in winter,followed in turn by autumn,spring and summer. Most of the hazy days are light and have visibilities between5 and 10 km. The number of mild or moderate hazy days,marked with visibilities of less than 5 km,has been increasing gradually since 2007. There have been more processes of sustained hazy weather,especially over the past three years. More than half of the hazy weather is made up of sustained processes and the longest incidence of hazy weather can last as long as 13 d. Much subject to meteorological elements,the hazy weather is likely to occur if the wind speed is light and relative humidity is large. To some extent,the haze decreases the measurable duration of insolation. One of the possible triggers for the frequent occurrence of hazy weather is the increased concentration of pollutants as a result of increasingly serious air pollution that has caused large amount of emission of vehicle exhaust,industrial waste gases and dust.