气象学报2016，Vol.74Issue(2)：189-199,11.DOI:10.11676/qxxb2016.013
武汉大气能见度与 PM2.5浓度及相对湿度关系的非线性分析及能见度预报
Study on the nonlinear relationship among the visi-bility,PM2.5 concentration and relative humidity in Wuhan and the visibility prediction
摘要
Abstract
Hourly observations of visibility,relative humidity (RH ),and particulate mass concentration in Wuhan for the peri-od from September 2014 to March 2015 have been analyzed in this study to investigate the relationship among these variables. Nonlinear prediction of visibility in Wuhan is explored preliminarily.It is found that the frequent occurrence of haze in Wuhan is largely responsible for the severe reduction in visibility.The formation and accumulation of fine particulates are two impor-tant factors inducing haze and low visibility.Both the RH and the particulate mass concentration affect the variation of atmos-pheric visibility.High RH and large fine particulate mass concentration can significantly reduce the atmospheric visibility.Un-der wet conditions (RH ≥ 40%),the visibility deteriorates because the hygroscopic growth of the fine particulate can efficient-ly enhance light absorption and scattering.When the RH is higher than 90%,the visibility decreases linearly with the increase in RH .Averagely,the visibility decreases by 0.568 km as the RH increases by 1%.Under dry conditions (RH <40%),the increase in the PM2.5 concentration becomes a critical factor for the rapid decrease in visibility.In urban areas where fine partic-ulates in the atmosphere are primary pollutants,the visibility has a nonlinear relationship with RH.This is partly attributed to the influence of PM2.5 on the visibility and partly attributed to light scattering effects of hygroscopic particles.Results also indi-cate that there exists a nonlinear relationship between the PM2.5 concentration and the visibility,which can be described by a power function.The correlation between the PM2.5 concentration and the visibility is most significant when the RH is less than 90% but larger than 80%.The sensitivity threshold of PM2.5 concentration for the atmospheric visibility decreases with in-creasing RH .Under dry conditions,the visibility of 10 km corresponds to a PM2.5 concentration threshold of 70 μg/m3 , whereas the value is 18-55 μg/m3 under wet conditions.Decreases in the PM2.5 concentration can lead to significant improve-ment in visibility when the PM2.5 concentration is less than 40 μg/m3 .In addition,results of preliminary experimentshave shown that the visibility prediction model,which is developed based on the neural network method,performs well in prediction of visibility in Wuhan.The correlation coefficient between observations and predictions can be up to 0.86,and the Root Mean Square Error (RMSE)is 1.9 km.The TS score is 0.92 for the visibility that is less than 10 km.These results indicate that the model has a crucial skill for haze prediction.关键词
武汉/能见度/PM2.5/相对湿度/非线性Key words
Wuhan/Visibility/PM2.5/Relative humidity/Nonlinear relationship分类
天文与地球科学引用本文复制引用
白永清,祁海霞,刘琳,陈城,林春泽,李武阶..武汉大气能见度与 PM2.5浓度及相对湿度关系的非线性分析及能见度预报[J].气象学报,2016,74(2):189-199,11.基金项目
资助课题湖北省气象局科技发展基金项目（2015Y04）、2014年湖北省财政业务建设项目、2015年湖北省山洪地质灾害防治气象保障工程。 （）
