| Air quality is getting more and more attention. The rapid development of economy has a positive effect on human beings and also has a negative effect. The positive effect is mainly reflected on the improvement of human's living standards, and the negative effect is reflected on the pollution of air where people live. In recent years, Nanning's economic has a trend of rapid development, and people's life quality can be improved, but it also has a pressure on the air, leading to the decline of air quality. The number of polluted days increased, and air quality issue has attracted people's attention. To this end, it has important significance to provide basis of decision-making for the relevant environment protection departments by studying the change characteristics of air and revealing the air quality status.The data which the paper uses has CE-318 monitoring data, satellite remote sensing MODIS data, air quality daily data, meteorological statistics data and meteorological remote sensing data. The paper studies the air quality of Nanning city, and analyses the variation tendency of air quality by Langley method, Dark pixel method, Statistical analysis method and backward trajectory simulation method. Firstly, the temporal trends of air quality in Nanning by using ground-based remote sensing data retrieving aerosol optical characteristics to investigate,and then combines with the ground monitoring data of pollutant concentration to analysis the correlation between the AOD and it,to explore the main material of air pollution in the study area. At the same time, the variation of aerosol optical depth in space is analyzed by using the remote sensing data. On the basis of the above analysis, the air quality of Nanning city is further studied. The main material of air pollution and variations of air quality in Nanning city are studied, moreover discussing the correlation between the meteorological factors and the air quality, AQI index and AOD. The potential sources of the air pollution in the target area are discussed by using the backward trajectory. Through the research and analysis, the paper mainly gets several conclusions as follows:The results which CE-318 inverts Aerosol optical properties show that the AOD value is highest in October and lowest from June to August. It shows that the air pollution in Nanning city in October is more serious, and the air quality is relatively good in summer, and then the changes of AOD in the month are relatively large. The phenomenon which the wavelength index is relatively large except in summer shows that the main controlling particle of air pollutant in Nanning is fine particles.The correlation between AOD and pollutants showed that the correlation of PM10 and AOD in summer was more obvious than that in other seasons, the correlation between PM2.5 and AOD was larger in the spring and Autumn and winter period, which indicated that the particle size of air pollutants in summer was larger than that in other seasons.From January in 2014 to May in 2015, the results which the satellite remote sensing MODIS inverts AOD show that the aerosol optical depth in winter is higher than that in spring and summer, and the variation of AOD is greater. The region where has higher AOD value is in the southern region of Guangxi. The AOD value is relatively high in minority areas in the north and center of Guangxi. Overall, the air quality in the study area is good, and air pollution happens in a few months.The relevance which satellite remote sensing MODIS inverts AOD and ground based remote sensing CE-318 inverts AOD pass the significant test. At the same time, ground based remote sensing inverting AOD and satellite remote sensing MODIS inverting AOD has the regularity in some degree. When AOD is high, the MODIS inversion results are lower than the CE-318 inversion results. In contrast, it is higher than the CE-318 inversion results.Statistical analysis is performance according to the air quality report data, the results show that the main pollutant in Nanning is PM2.5 and PM10, and the air at some moments will appear ozone and sulfur dioxide pollution. As a whole, the air quality in autumn and winter is poor, and air pollution is obvious. The air of some days in spring is polluted, and the air quality in summer is the best.The result which analyses the relevance of meteorological factors and AQI index of air quality shows that the temperature has negative effect on the air quality, and the air pressure has a positive effect on it. The wind speed has a positive or negative effect on it, and the visibility is negatively related to the air quality. The correlation analysis between AQI index and AOD show that positive correlation exists between them and through significance test. The calculation results of them are basically consistent.The analysis of the pollutant backward trajectory PSCF shows that the air pollution in Nanning is greatly affected by its own factors, the emission pollution in the adjacent area effects on its environment quality, and it is also affected by the long distance transmission in some remote areas. The superposition between PSCF analysis and the result which MODIS inverts AOD shows that which MODIS inverts AOD is corresponding higher in the region where the WPSCF value is larger. |
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