Distribution Characteristics Of Air Quality Index And Its Relationship With Meteorological Factors In 31 Provincial Capitals In China

Objective:With the sustained and rapid growth of urban economy in our country,the city scale expands unceasingly,urban haze weather has been appeared frequently with a wide range,the problem of city’s air pollution has became China’s environment problems that attracts the most attention currently.The increasingly serious problem of air pollution have the increasingly enormous threat to the resources,environment,residents’ s health.In our country,air pollution is not a problem in a city,it is a national problem.under the background of the transformation of air pollution,PM10、SO2、NO2 for the necessary parameters calculated by the API is not be able to accurately characterize the actual situation of China’s air pollution.So,the state environmental protection department has launched a new index in 2013-air quality index(AQI)used to represent the air quality situation,In addition,the fine particulate matter(PM2.5),which has a significant impact on atmospheric visibility and human health,is incorporated into the routine monitoring of pollutants.This paper aims to study the distribution characteristics and changing trend of air pollution in provincial capital cities by using a new quantitative index of air quality—AQI.Correlation analysis is used to study the relationship between AQI and meteorological factors.Finally,the objective of the study is to reflect the situation of environmental air quality in China,At the same time,it also provides a scientific basis for formulating policies,laws and regulations to prevent and control air pollution.Methods: Air quality index(AQI)data are from the People’s Republic of China environmental protection department data center(http://datacenter.mep.gov.cn/index)including daily air quality index(AQI),the primary pollutants and air quality level.Meteorological data are from the web site(https://rp5.ru/ China weather_)and the daily meteorological data published in the website,the weather data from meteorological stations provided by the meteorological data of international free exchange system.Time is on January 1,2014 to December 31,2016,we choice all the provincial capital citiesapartfrom Hong Kong,Macao,Taiwan in our country,a total of 31 cities.Classify thecollected AQI and meteorological databy the Excel;Using professional software Arc GIS draw statistical map;Correlation analysis between AQI and meteorological factors by SPSS’s two variable correlation analysis,The correlation coefficient more than zero is for positive correlation and less than zero is for negative correlation,and P<0.05 is significant.Inthe last,According to the results of statistical analysis,we describes the spatial and temporal distribution characteristics of AQI in 31 provincial capitals and its correlation with meteorological factors.Results: 1 AQI in north was higher than the south city,the AQI obviously decreased from north to south,and until Haikou,the AQI was the lowest;AQI high value area were mainly distributed in the north plain area.From 2014 to 2016,the annual AQI value was 98±25、91±22、88±22 respectively,showing a clear downward trend.China’s capital city air quality index(AQI)as a turning point in summer,the winter to summer AQI presented slash state,AQI increased after the summer,and rose to the highest until the winter,so,the highest AQI value was in winter and the lowest was insummer.But except for Lasa,The highest AQI was spring in Lasa,The change of AQI was not obvious in other seasons.it also was found that there was no significant difference of AQI value in Guangzhou,the highest AQI value in winter and no significant difference in spring,summer and autumnin Beijing.2 The top five cities of the proportion of pollution days in 31 provincial city were Jinan(65%)、Zhengzhou(59%)、Wuhan(53%)、Beijing(50%)、Shijiazhuang(49%),The lower five cities of the proportion of pollution days were Haikou(2%),Kunming(2%),Fuzhou(4%),Lasa(7%),Guiyang(8%);From 2014 to 2016,the proportion of pollution days were 35%,29% and 28%,respectively.The number of annual pollution days decreased year by year and the air quality improved;On the whole,the proportion of pollution days in northern cities(19%)was greater than the southern city(11%),Air quality in northern cities was worse than that in the south.3 PM2.5 was primary pollutants in most of the capital cities in our country in pollution days,the second pollutant was PM10,ozone(8ho3).The primary pollutant was PM10 in Lanzhou,Huhehaote,Lasa,the second pollutant was PM2.5,PM2.5,ozone(8ho3)respectively.PM2.5 was the primary pollutant on fall and winter and all year of seven areas in China;In the spring,PM10 was the primary pollutant in the northwestern region;In the summer,ozone(8ho3)was the primary pollutant in seven areas of our country.4 The average monthly temperature and the monthly AQI in seven regions(northeast,northwest,north China,central China,east China,southwest,south China)negatively correlated,the correlation coefficient were-0.740、-0.853、-0.684、-0.752、-0.653、-0.701and-0.599 respectively.The average monthly humidity and the monthly AQI in four areas(central China,southwest,south China,east China)negatively correlated,the correlation coefficient were-0.526、-0.519、-0.559and-0.553 respectively.The average monthly wind speed and the monthly AQI in two areas(North China,east China)negatively correlated,The correlation coefficient were-0.384、-0.451 respectively.Conclusion: Air pollution in our country as a whole show the seasonal feature of higherin winter and lowerin summer obviously,and the space feature of higherin north and lowerin south obviously;the top five of 31 capital cities of air pollution days ratio are Ji’nan city(65%),Zhengzhou(59%),Wuhan(53%),Beijing(50%),Shijiazhuang(49%)respectively;the lowest five of 31 capital cities of air pollution days ratio are Haikou(2%),Kunming(2%)Fuzhou,(4%),Lhasa(7%),Guiyang(8%)respectively;2014 to 2016 pollution days ratio are 35%,29%,28%,the average annual pollution days decreased year by year,the air quality has improved;the north cities of air pollution days ratio(19%)is greater than the south City(11%),the air quality of north cities are better than southern;PM2.5 is primary air pollutant in our country,the second air pollutant is PM10,ozone(8ho3),ozone(8ho3)is primary air pollutant in the summer.In northwest China PM10 is the primary air pollutant in the spring;there are significant negative correlation relationship between air quality index(AQI)and regional meteorological factors(temperature,humidity,wind speed).The higher the temperature,the lower the AQI,the lower the temperature,the higher the AQI.Low temperature in winter,AQI is higher,Humidity has clear effect to regional AQI.The size of the wind speed has a direct impact on regional AQI value change,the bigger wind speed,the smaller AQI,which indicates that pollutants is easy to spread;the smaller wind speed,the bigger the AQI value,which indicates that pollutants is not easy to spread.In conclusion,air pollution in cities of our country has different characteristics each area each season,it correlation with regional meteorological factors,so we highly suggest that region-oriented air pollution management plans.