潍坊市灰霾天气特征及影响因素

Characteristics and Influencing Factors of Haze Weather in Weifang City

根据潍坊市国家环境空气质量监测点位和国家气象台站监测数据,对潍坊市2019年灰霾发生情况进行统计,并分析了灰霾天气与气象要素、环境空气质量的关系。结果表明:潍坊市2019年按小时计算的灰霾发生频率为22.4%。灰霾在冬季和秋季相对高发,发生次数占全年小时灰霾数的66.7%,发生比例为56.2%。从时间上看,灰霾发生频率呈正弦曲线分布,在早上06:00—07:00发生频率最高,17:00前后发生频率相对较低。灰霾发生时风速、温度与能见度呈正相关关系,相对湿度与能见度呈负相关关系。潍坊市灰霾现象主要发生在风速小于3 m/s、相对湿度大于30%时,当风速大于5 m/s、相对湿度小于10%时极少发生灰霾。PM_(2.5)是影响灰霾发生的主要污染因子,与能见度的相关系数最高。灰霾主要发生在48μg/m^(3)<PM_(2.5)质量浓度<239μg/m^(3)条件下,占灰霾总次数的84%;而当PM_(2.5)质量浓度>140μg/m^(3)时灰霾发生频率达到100%;灰霾天气统计期间潍坊市空气中PM_(2.5)与PM_(10)的质量浓度平均比值为0.52,其中,灰霾发生时比值为0.75,非灰霾时比值为0.43。随着灰霾程度的加重,PM_(2.5)/PM_(10)逐渐增大;当灰霾程度达到轻度及以上时,PM_(2.5)/PM_(10)大于全年平均值。

Based on the data of national ambient air quality and meteorological monitoring stations of Weifang City,the haze occurrence in Weifang in 2019 was statistically analyzed,and the relationship between haze weather and meteorological factors and ambient air quality was analyzed.The results showed that the hourly occurrence rate of haze in Weifang in 2019 was 22.4%.The haze was prone to occur in autumn and winter(66.7%of the total,occurrence rate 56.2%).In the view of occurrence time,the occurrence frequency of haze showed a sinusoidal distribution,with the highest occurrence frequency between 06:00 and 07:00 in the morning,and relatively low occurrence frequency around 17:00.Wind speed and temperature were positively correlated with visibility,while relative humidity was negatively correlated with visibility.The haze of Weifang mainly occurred when the wind speed was below 3 m/s and the relative humidity was above 30%.In contrast,when the wind speed was above 5.0 m/s and the relative humidity was below 10%,the haze rarely occurred.PM_(2.5)was the main pollution factor that affected the occurrence of haze and it had the highest correlation coefficient with visibility.The haze mainly occurred when the PM_(2.5)was between 48 and 239μg/m^(3),accounting for 84%of the total hours.Moreover,when the PM_(2.5)was above 140μg/m^(3),the occurrence rate of haze would reach 100%.During the haze statistics period,the average mass concentration ratio of PM_(2.5)to PM_(10)in Weifang was 0.52,in which the ratio during haze was 0.75 and that during non-haze was 0.43.With the increase of haze degree,PM_(2.5)/PM_(10)gradually increased.When the haze degree was mild or above,PM_(2.5)/PM_(10)was greater than the annual average.