Correlation Analysis Between Urbanization Level And PM2.5 Concentration In Shaanxi Province

Since the 1990s,China has coming into the fast urbanization stage.The continuous development of the city has brought about regional imbalances and environmental pollution.Air pollution has become the major environmental pollution problem faced by most large and medium-sized cities in China.The research on the relationship between urbanization and air pollution can provide an important reference for sustainable urban development.At present,the statistical information is used to calculate the urbanization-related indicators to analysis the relationship between urbanization and air pollution.However,there are some restrictions on the research because of the possible human error and the lack of statistical data in some regions.The DMSP/OLS nighttime light image captures light source information at the surface and monitors lights in towns and villages to reflect urban features.Because of its advantages of wide data coverage,easy access,and relatively easy extraction of target information,it has been introduced to carry out relevant research in urban areas.Firstly,this paper uses the correction method based on the invariant target area to correct the DMSP/OLS night light data and eliminate the effect of the saturated pixels in the bright cores of urban areas and uncomparable problem of image data.Secondly,the corrected DMSP/OLS nighttime light image are used to calculate the nighttime light index to reflect the urbanization level and extract the information of urban land use to analysis the urban expansion in Shaanxi Province.At the end,based on the nighttime light index,GWR model was selected after evaluating the fitness of two different models to simulate and analyze the correlation between the urbanization and the PM2.5 concentration.(1)Statistical data as auxiliary data to analysis the urbanization is effective.It can accurately reflect the level of urbanization and changes in urban spatial pattern in Shaanxi Province.(2)The development of different regions is unbalanced.The overall development of Guanzhong region is stronger than that of Northern Shaanxi and south of Shaanxi.During 1998-2013,Xi’an has developed from rapid development to high speed development.The development speed of the latter has slowed down slightly.The built-up area was planar distribution in the central Xi’an.The urban expansion was dominated by the development zone and was developing towards the north and southwest.The built-up area occupies the highest proportion in the total area of the city compared with other cities in Shaanxi province.The development speed of Yulin city has developed from medium to rapid and will continue to increase.The built-up area of the central Yulin was mainly towards southwest expansion.Due to the resources as the leading factor,there was gradually developed into the industrial belt along the Great Wall.The development of the six counties in the north is better than that of the six counties in the south.The development of Hanzhong city was relatively slow,and the promotion of traffic conditions has accelerated the pace of the development of the city.(3)The spatial and temporal distribution characteristics of the concentration of PM2.5 in Shaanxi province were analyzed by using the average PM2.5 concentrations images of Chinese mainland.The concentration of PM2.5 in Guanzhong and southern Shaanxi continued to increase,and the concentration of PM2.5 in Guanzhong area was the highest in Shaanxi province.In 2008,the concentration of PM2.5 in Shaanxi province declined and the air quality improved,but after that,the concentration of PM2.5 was enhanced and the air quality decreased.(4)Based on the correlation study between nighttime light data and PM2.5 concentration,the relationship between urbanization level and PM2 5 concentration in Shaanxi Province was analyzed,and the influence of urban development in each district of Shaanxi Province on PM2.5 concentration was discussed.The level of urbanization in each region of Shaanxi Province has different effects on the concentration of PM2.5.The concentration of PM2.5 in northern Shaanxi is relatively low,there is no significant positive correlation between the level of urbanization and the concentration of PM2.5.In the process of urban development,government has paid attention to environmental protection.The concentration of PM2.5 in Guanzhong area is the highest,and the influence of urban development on regional PM2.5 concentration is relatively consistent.The concentration of PM2.5 in this area is affected by both urban development and terrain conditions.The concentration of PM2.5 in southern Shaanxi is affected by the development of the city.During the urban development,more attention should be paid on the environment.The study studied the urbanization level of Shaanxi Province based on nighttime lighting data and quantitatively analyzed the relationship between the urbanization level and the concentration of PM2.5,then explored the impact of urbanization on the concentration of PM2.5 in Shaanxi Province.The study results provide reference for the sustainable development of the region and provide a theoretical basis for the introduction of nighttime light data for related research in the field of eco-environment.