Study On Atmospheric Environment And Vegetation Changes In Yinchuan City During2001-2009

The acceleration of urbanization has led to a series of environmental problems, such as the urban heat island effect and atmospheric environment pollution. In the course of the study on the ecological and environmental problems, only a few studies made full use of the remote sensing technique method on the research of the land use, the vegetation coverage and its variation, and combined the situation of air pollution and city thermal environment with the NDVI. With the constant expansion and population increasing, city morphology, function and regionalization of Yinchuan, which is the capital of Ningxia Province, have dramatically changed, so urban heat island effect is more and more obvious. Based on the MODIS NDVI and the surface temperature product data as well as the pollutant concentration data, this article used the mean method、difference method、correlation analysis and linear regression methods to analyze the vegetation changing and the heat island effect of Yinchuan during2001-2009in the spatial and temporal scale, and studied the relationship among the NDVI, the surface temperature and the pollutant concentration, the main findings of this paper are as follows:(1) The air quality in Yinchuan was generally good during2001-2009, PM10was the most serious pollutant, the serious pollution occurred in spring and winter, of the phenomenon was related with the long heating period and the dust weather. The Xi Xia area had the most serious pollution in three function areas, all of the pollutant concentrations did not exceed the national secondary standard in the area of Xing Qing and Jin Feng area, and the PM10was the only exceeding standard index in the Xi Xia area. Throughout the year, the air quality of January、February and December were the worst, and from June to August were the best.(2) The NDVI of Yinchuan showed weak increase trend during2001-2009, the values of NDVI, from big to small, were Summer, Autumn, Spring and Winter. The vegetation coverage of Yinchuan was relatively high during the nine years. Through the contrast of the NDVI values between suburban and urban, the results showed that the vegetation growth would be affected by some other factors, which should include the atmospheric environment.(3)The land surface temperature of Yinchuan showed slightly decreasing trend during2001-2009, but the high-temperature area was gradually increased, the urban heat island effect was more and more obvious, and had continuous expansion. The urban heat island effects in the Xi Xia area as well as He Dong airport were also obvious. With the seasons changing, there also had obviously urban heat island effect, and the area of the surface temperature anomaly positive values were, from big to small, Winter, Spring, Autumn and Summer, which showed the opposite tendency with the changes of the vegetation coverage.(4) There had very significant relationship between NDVI and surface temperature in Yinchuan during2001-2009in the spatial and temporal scale, and there had negative correlation in temporal scale but positive correlation in spatial scale. The negative correlation between SO2, PM10, and NDVI, surface temperatures were extremely significant in three functional areas, and there had extremely significant negative correlation between NO2and NDVI in the Xi Xia and Jin Fong area, but significant negative correlation in Xing Qing area. The NDVI is more sensitive to SO2and PM10, and the surface temperature is more sensitive to SO2.