摘要
为了研究合肥市能见度影响规律,为改善城市大气能见度提供科学依据,利用合肥市2013年1月—2015年12月的气象观测数据和颗粒物质量浓度数据,采用统计分析方法研究了合肥市大气能见度与相对湿度和PM_(2.5)质量浓度的定量关系,以及不同等级能见度下相对湿度和PM_(2.5)浓度的统计特征。结果表明,PM_(2.5)质量浓度与相对湿度共同影响合肥市大气能见度变化,较低相对湿度下(RH<60%),能见度降低主要受PM_(2.5)质量浓度升高的影响;较高湿度条件下(RH≥60%),能见度降低主要是由于相对湿度增加造成的大气粒子吸湿增长导致消光性能增大,且这种作用在污染程度较轻时更加突出。RH≥60%时,相对湿度每增加1%,平均能见度降低0.172 km;当RH≥90%时,平均能见度基本在5 km以下。PM_(2.5)质量浓度与能见度呈幂函数关系,40%≤RH<60%时,PM_(2.5)的影响作用最显著;PM_(2.5)质量浓度对能见度的影响阈值随相对湿度增加而减小,当PM_(2.5)质量浓度低于46μg?m^(-3)时,能见度随着PM_(2.5)质量浓度降低而迅速增大。随着相对湿度增加,或者PM_(2.5)质量浓度增加,低能见度出现频率呈上升趋势;高湿度、高细颗粒物浓度均可导致低能见度的出现。当前一日能见度低于7km,当日相对湿度大于75%,且PM_(2.5)质量浓度大于65μg?m^(-3),当日能见度超过75%的比例在5 km以下。当前一日PM_(2.5)质量浓度达到中度及以上污染,当日能见度随着相对湿度增加逐渐减小,RH≥80%时,能见度低于5 km的比例达到70%。
To understand the impacting factors of the visibility in Hefei,and provide scientific basis for the urban atmospheric visibility improvement,the hourly meteorological and environmental observations from January2013to December2015in Hefei city were used to investigate the relationships among atmospheric visibility,relative humidity(RH),and PM2.5mass concentration.The statistical relationships between RH and PM2.5were set up for different atmospheric visibility grades.It was found that atmospheric visibility in Hefei was jointly controlled by both RH and PM2.5.Under low RH conditions(RH<60%),the decrease in visibility was mainly ascribed to the increase of the PM2.5mass concentration.High RH and PM2.5mass concentration can significantly reduce the atmospheric visibility.Under high RH conditions(RH≥60%),due to the hygroscopic growth of the fine particulate can efficiently enhance light absorption and scattering,the visibility decreases more obvious in slight pollution.On average,the visibility was reduced by0.172km with1%increment of RH when RH≥60%.When RH≥90%,the average visibilities were mostly less than5km.The best fitting relationship between the PM2.5mass concentration and the visibility was a power function,and the effects of PM2.5on visibility were strongly significant when the RH is less than60%but larger than or equal40%.The PM2.5mass concentration threshold that influences the atmospheric visibility decreases with increasing RH.Particularly,decreases in the PM2.5mass concentration can lead to rapid increase in visibility when the PM2.5mass concentration was less than46μg?m-3.As the RH increases,or PM2.5mass concentration increases,the frequency of low visibility rises.High RH and large PM2.5mass concentration can significantly induce the occurring of lower atmospheric visibility.The factor of probability that visibility<5km in a day was greater than75%,when the visibility was below7km in its previous day and RH>75%with PM2.5>65μg?m-3in the day.When the PM2.5mass concentration reaches the moderately
作者
张浩
石春娥
吴必文
杨元建
ZHANG Hao;SHI Chune;WU Biwen;YANG Yuanjian(Anhui Institute of Meteorological Sciences, Key Laboratory of Atmospheric Science and Satellite Remote Sensing, Hefei 230031, China;Shouxian National Climatology Observatory, Shouxian 232200, China)
出处
《生态环境学报》
CSCD
北大核心
2017年第6期1001-1008,共8页
Ecology and Environmental Sciences
基金
安徽省省级环境保护科研项目(2015-002)
中国气象局气候变化专项(CCSF201726)
关键词
能见度
相对湿度
PM2.5质量浓度
定量关系
合肥
Visibility
Relative humidity
PM2.5 mass concentration
Quantified relationship
Hefei
