Temporal And Spatial Patterns And Influencing Factors Of Air Quality In Urban Agglomeration Of The Yangtze River Delta

In recent years,accompanied by the continuous improvement of China's modernization,air quality problem has gradually become one of the social hot issues.The news words such as‘surrounded by haze',‘PM_2.5.5 exceeding the standard',‘APEC blue'and‘parade blue'have become commonplace.Polluted air causes great inconvenience to transportation,health and life.In response to the issue of air quality control,the State Council issued the"Ten Articles of Atmosphere"to strengthen the prevention and control of atmospheric In the second half of 2013.Many scholars at home and abroad have combined their discipline advantages to conduct research on related air quality assessments,analysis,and predictions.This has become a hot issue.To solve the problem of air quality pollution,it is necessary to grasp the dynamics of air quality in real time,conduct comprehensive assessment and management of air conditions,enventually control air quality pollution,and achieve sustainable environmental development.By extracting the spatial distribution data of urban agglomeration in the YRD,according to the State Council's latest plan in 2016,the current study area were divided into‘a core area and five metropolitan areas'.With the aid of mathematical statistics,self-organizing feature mapping network models and GIS analysis,the difference of air quality in a wide range of urban agglomerations were obtained.A comparative analysis of the air quality of the Yangtze River Delta urban agglomeration is conducted from spatial-temporal perspectives,mainly based on quantitative analysis of the meteorological and social development factors.During the period of atmospheric treatment,the temporal and spatial distribution of air quality in the Yangtze River Delta urban agglomeration in 2014-2016 was detailed to provide a scientific basis for the prevention and control of air pollution in the region.The main results show that:?1?First of all,the‘one core and five metropolitan areas'of the Yangtze River Delta have different levels of pollution from the overall characteristics.In three years,the Ningbo metropolitan areas have the least number of air pollution days,followed by the metropolitan areas of Shanghai and Hangzhou,followed by the metropolitan area of Suzhou,Wuxi,and Suzhou.The Nanjing City and Hefei metropolitan circles have the largest number of pollution days.The similarity is that mild air pollution days accounts for a large proportion.Nitrogen dioxide,sulfur dioxide,and carbon monoxide have less rate of exceeding the standard.Particulate matter and ozone pollution become mainstream.From November to March,pollutants are mainly PM_2.5;from April to September,ozone is the main pollutant.?2?Secondly,in terms of time distribution,AQI decreased year by year and showed a seasonal variation:the best in summer and the worst in winter.The spatial gradient of AQI significantly changed in the spring,autumn and winter,showing a distribution pattern in which AQI was high in the north area and low in the south,while the AQI in summer had little change in the spatial gradient,and the spatial variation was not obvious.The status is:Ningbo metropolitan area?better?>Shanghai,Hangzhou metropolitan area?better?>Suzhou,Wuxi and Changzhou metropolitan area?better?>Nanjing metropolitan area and Hefei metropolitan area.And through the establishment of self-organizing feature mapping neural network SOFM clustering model,the effect is good.The clustering results are consistent with the above sort of metropolitan circle.?3?In the end,based on the results of the spatial and temporal distribution of"one core and five metropolitan areas",a multi-factor principal component regression,stepwise regression and partial correlation analysis methods were used to deeply analyze the influencing factors of the air quality in the study area.Thus quantitatively and qualitatively express AQI and meteorological factors such as air pressure and temperature.The relationship between meteorological elements and AQI was found to be highest in Ningbo and lowest in Nanjing.Six major factors were selected among social development factors.The proportion of second industry in GDP is most relevant to AQI and the population and population density have the least influence.And topographic distribution factors are also related to air quality.