Research On Temporal And Spatial Pattern Changes Of Xinjiang Cities Based On DMSP/OLS Nighttime Light Data

Under the background of accelerating the implementation of new urbanization strategy in China,the research on the change of urban spatial pattern is still a very important subject.Influenced by many factors,urban spatial pattern is changing constantly.At present,domestic and foreign scholars have carried out a lot of research on the process of urban pattern change.The discussion of urban spatiotemporal pattern based on DMSP/OLS nighttime lighting data is also a hot topic in current research.Due to the special nature of the geographical location of Xinjiang,the development of Xinjiang plays a vital role for China.However,with the study of nighttime lighting data,there are few studies on Xinjiang cities.Therefore,it is of great theoretical significance to carry out research on the temporal and spatial patterns of Xinjiang cities.This paper selects the stable DMSP/OLS nighttime lighting data images of 2001,2005,2009 and 2013.The ten major cities in Xinjiang Uygur Autonomous Region are used as research objects,and the spatial and temporal analysis of night light data in Xinjiang cities was conducted with RS and GIS methods to study their morphological characteristics.It also explores the spatial and temporal heterogeneity of economic development in different regions to make up for the lack of statistical data in spatial description,enrich the theoretical research of urban geography and urban science,grasp the urban development context in time,and provide a reliable theoretical basis for the balanced development of Xinjiang’s cities.The main research contents and conclusions are as follows:(1)Based on the DMSP/OLS nighttime lighting image,the built-up areas of ten cities in Xinjiang were extracted by reference to the built-up area in the statistical data to determine the boundary area of the urban built-up area.At the same time,the extraction results were spatially verified by means of Google Earth imagery and Landsat 8 remote sensing imagery.The research shows that the method can extract the urban built-up area more accurately,and the nighttime light image can represent the urban built-up area in space.(2)Through the calculation of time series of urban compactness,urban expansion intensity,urban expansion elasticity coefficient,urban development center of gravity,therationality of urban development pace is measured,and the spatial and temporal patterns of urbanization are quantified.Studies have shown that there are mainly urban problems in Urumqi and Changji.Urban development needs to pay attention to urban transformation,and the rapid expansion will result in waste of urban resources.In recent years,Kashgar City is in a stage of rapid outward expansion,with various development indicators being good,and the development model is worth learning from other cities.(3)On the nighttime DMSP/OLS nighttime light image in Xinjiang,the light pixels with higher gray value are concentrated in the vicinity of national highways and provincial highways,and gradually formed many urban systems with traffic as the link,which fully illustrates the importance of traffic convenience to regional development.In 2013,compared with 2001,the high value pixels of urban night lights in Xinjiang showed a dynamic development trend of continuous expansion around the main cities as the center.The links between cities are getting closer and closer,and they are also driving the development of cities along the route while developing their own economy.(4)Based on the lighting data,a relatively simple lighting index CNLI is constructed without weighting.This index can reflect the economic development status of the region,and the larger the lighting index is,the better the economic development level of the region is.It is calculated that the light index of Shihezi City,Kashi City and Yining City is relatively high,and small-area cities have become the hotspot of Xinjiang’s development.Combined with relevant statistical data,the stepwise regression method is used to explore the change mechanism of the light index,and a regression model capable of predicting the light index is constructed.According to the analysis,the light index is mainly related to the proportion of urban villages and industrial and mining land in the total area.The coefficient of determination of the model is 0.873,which indicates that the proportion of urban villages and industrial and mining land in the total area can be used to accurately predict the regional light index.