| Aerosol Optical Depth (AOD) is an important optical parameter which shows the physical properties of atmospheric aerosols. It describes the characteristics of atmospheric aerosol extinction which reflects the effect of aerosol extinction of solar radiation. Aerosol content can be estimated from AOD. It can also assess the extent of air pollution. It has practical significance to scientific prediction for particulate pollution and it’s a very effective method to environmental monitoring by studying the temporal and spatial distribution of aerosol optical depth.Guangdong Province is one of the most economically developed regions in our country, so its environmental problems can not be underestimated. In the research, MOD04 aerosol products from MODIS-Terra dataset (C051) was used.Aerosol optical thickness in the region of Guangdong from 2001 to 2015 was extrated in order to analyze the spatial and temporal distribution over Guangdong province.After that, the change of atmosphere environment in the past 15 years can be explored. Then aerosol products MOD04 data was used to acquire temporal dynamics of AOD over Guangdong province during a haze, besides it was combined with meteorological data and the use of airflow trajectory analysis method for this research. Pollutants diffusion process were analyzed at last, while the origin and destination of particulate matter were preliminarily explained.Finally, the calculated AOD data from 2001 to 2015 in the research area was used combining with meteorological station data, TRMM 3B43 rainfall data, DMSP/OLS night lights, Landsat8 OLI image, SPOT NDVI, elevation data and the economy/population data in " Statistical Yearbook of Guangdong Province " and other data. They were anlyzed through regression analysis, trend curve contrast, maps comparison in order to get the relevance between various factors and AOD.The main results of this research comprise:(1) In the past 15 years, the average value of AOD in the Guangdong region is 0.5, and it has some annual fluctuations.Results show that AOD over Guangdong Province increased first and then decreased. Average AOD in 2007 over Guangdong Province increased 14.97% compared with 2001, while average AOD in 2015 decreased 29.10% compared with 2007; During the spring time, AOD reaches the largest value in March or April according to the monthly analysis; AOD is negatively correlated with DEM and NDVI, but it is positively correlated with the night light. There is a phenomenon that AOD is high in densely populated areas. For example, the high AOD areas are concentrated in groups over Pearl River Delta (PRD) urban agglomeration region, while the high AOD areas outside the PRD are scattered. It indicates that human activities have a significant impact on AOD. Multi-year mean AOD over the PRD, eastern, western, mountains region of Guangdong province in the past 15 years were 0.603,0.439,0.506 and 0.447.(2) Analysis shows that faster wind speed was conducive to the transfer and diffusion of pollutants, so wind has a significant role to disperse pollutants. The trends analysis between AOD and precipitation showed that rainfall has a significant scouring effect on the aerosol.(3) After 2007, the decrease of AOD mainly associated with the decline in the proportion of secondary industry. In addition, changing climatic conditions and the improve of the vegetation coverage may also have some effects.In future studies, meteorological and statistical data should be added more in order to analyze the factors that affect the changing trends of AOD.All in all, MODIS MOD04 aerosol product data was mainly used in the research. The humid and rainy Guangdong province was taken as the research region. The spatial and temporal changes of aerosol optical thickness over this region were analyzed in detail. Further more, the affecting factors of AOD were explained.This research may has some reference value for the energy conservation and environmental protection in the region of Guangdong. |
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