Research On The Response Relationship Between AOD And Land-Use Change In China

With the rapid development of urbanization and industrialization,China has become one of the countries with the most serious air pollution in the world,posing huge challenges to climate change and human health.At the same time,in the context of urbanization,land use/land cover is undergoing tremendous changes in the form of urban expansion,encroachment on farmland,and vegetation reduction,which directly or indirectly affects the deposition and diffusion of air pollutants,thereby further deteriorating the atmospheric environment.Aerosol Optical Depth(AOD)is one of the main physical indicators to quantify atmospheric turbidity and atmospheric pollution.Therefore,understanding the temporal and spatial dynamic characteristics of AOD and land use,and exploring the impact of land use on AOD is crucial for preventing and improving air pollution and sustainable management of resources.Based on the MODIS 3 km C006 Level 2 aerosol data product from 2005 to 2020,this paper comprehensively uses Geographic Information System(GIS),Remote Sensing(RS),Generalized Additive Model(GAM),The center of gravity model,Geographically Weighted Regression(GWR)model and other methods have carried out from three aspects:the spatiotemporal characteristics of AOD and land use,the spatiotemporal relationship between AOD and land use,and the spatial response of AOD to land use.The main work and main conclusions in this paper are summarized as follows:(1)Based on the satellite remote sensing aerosol data from 2005 to 2020,the temporal and spatial variation characteristics of AOD were analyzed from the time scales of year,season and month.The results show that:In terms of time,AOD fluctuated from 2005 to 2013 but remained at a high level,with a change rate of-0.0010/9a(P<0.05),while from 2013 to 2020,AOD showed a significant downward trend at a rate of 0.0129/8a.2013 is a turning point for AOD from basically unchanged to rapidly declining,which may be related to the air pollution control measures implemented in 2013.The annual average AOD value is the highest in spring,the second in summer and the lowest in autumn.In terms of space,AOD is generally bounded by huhuanyong line,showing a spatial distribution pattern of high in the East and low in the West.Large areas of high pollution accumulation areas are mainly distributed in central and eastern China,and this trend has not changed in the past 16years.(2)The results showed that there were significant differences in AOD concentrations among the six main land use types in China,with the highest AOD value in construction land,followed by water and cultivated land,and the lowest AOD value in forest and grassland.On the national scale,cultivated land,water area and construction land are positively correlated with AOD,while woodland,grassland and unused land are significantly negatively correlated.In addition,as the area of each land use type increases,AOD shows complex nonlinear response.Among them,there is a phenomenon of"Environmental Kuznets Curve"in the nonlinear relationship between AOD and construction land.When the area of construction land reaches a certain scale,AOD decreases slowly or tends to be flat.The contribution analysis shows that cultivated land is the main contribution of aerosol in China,and its relative contribution value is 2.40.Although the area of construction land only accounts for 2.08%～2.83%nationwide,the contribution of construction land to aerosol in China can not be ignored.(3)Based on the gravity model,the spatial coupling relationship between AOD and land use is explored.The results show that the gravity centers of AOD,forest land,construction land and cultivated land are located in the east of China’s geometric center,while the gravity centers of grassland,water area and unused land are located in the Northwest.From 2005 to 2020,the distance between the center of gravity of each land use type and the center of gravity of AOD generally showed a downward trend,and its spatial overlap increased significantly,indicating that the spatial coupling between AOD and land use was increasing.The GWR model further revealed spatial heterogeneity of the impact of land use on AOD.The results show that the fitting degree of the GWR Model between AOD and land use is between 0.758 and 0.924,and the model fitting effect is good.Among them,areas with R~2 greater than 0.70 are mainly distributed in the east of huhuanyong line,while areas with R~2 less than 0.50 are mainly in the northwest,indicating that AOD in the east of huhuanyong line has a more significant response to land use.From the regression coefficient of GWR Model,the relationship between the six land types and AOD shows both positive and negative effects,and the degree of impact has significant spatial differences.Among them,the expansion of construction land will lead to more pollution in Northeast China than in other regions,and the increase in forest and grassland area will reduce AOD in Northwest China more than other regions in China.