Spatiotemporal Pattern Of Zhengzhou Metropolitan Area Based On NPP/VIIRS And POI Data

The metropolitan area is the product of the advanced stage of industrialization and urbanization,which is the important space carrier leading the regional development,and also the strategic highland for the city to participate in the domestic and international competition.Zhengzhou metropolitan area,as the forerunner of the rise of the central plains urban agglomeration,plays an important role in enhancing the competitiveness of the urban agglomeration.Therefore,to strengthen the research on the spatial and temporal characteristics of Zhengzhou metropolitan area can reflect the future development direction of the Central Plains urban agglomeration and even Chinese cities to a certain extent.With the continuous development of remote sensing data and geographical data,NPP/VIIRS and POI data can intuitively and accurately reflect the intensity of human social activities,and have advantages such as easy access,long time series,fast updating speed and large spatial span.Therefore,they are often used in the research on urban spatial and temporal evolution and the spatialization of social and economic data.This paper takes NPP/VIIRS and POI data from 2012 to 2018 as the basic data and NDVI and statistical yearbook data of the corresponding years as the auxiliary data to explore the spatial and temporal characteristics of Zhengzhou metropolitan area from the two aspects of urban built-up area evolution and expansion and the spatial and temporal characteristics of economic development.The main work and conclusions of this study include:(1)Urban built-up area extraction:the built-up area extraction index research was carried out through the traditional methods such as mutation detection method and statistical data comparison method,as well as based on the long time series NPP/VIIRS,POI,NDVI and statistical yearbook data.The NPP&POI and NDVI comprehensive index method is applied to the extraction of urban built-up areas in Zhengzhou metropolitan area.It is proved that the comprehensive index method has a better extraction accuracy than the mutation detection method and the statistical data comparison method,and has a better feasibility.(2)Analysis of spatial-temporal evolution of built-up area expansion:Based on NPP&POI&NDVI comprehensive index method,the built-up area of five prefecture-level cities in Zhengzhou metropolitan area was extracted,and the evolution of urban built-up area expansion was analyzed from two dimensions of time and space.The time series is mainly explored by the total expansion area of built-up areas,expansion amplitude index,expansion elasticity coefficient,expansion intensity and expansion rate.Spatial characteristics were analyzed by compactness index,landscape pattern index,change of center of gravity and expansion direction.The results show that the built-up area of Zhengzhou metropolitan area has a polynomial growth trend from 2012 to 2018 during the process of urbanization expansion.The average annual expansion intensity and expansion rate increased from 2012 to 2016,and reached the maximum value of 8.38%and 7.96%during 2014 to 2016,respectively.From 2012 to 2018,the compactness index of Zhengzhou metropolitan area decreased continuously,and the urban built-up area evolved from the original agglomeration state to scattered patches,indicating that the compactness index presented a decreasing trend with the increasing study area.The center of gravity of Zhengzhou metropolitan area has always been located in Zhengzhou,and the direction of the center of gravity is southeast.The center of gravity transfer was larger during 2014-2016,with a distance of 1.6km.The center of gravity transfer was the smallest during 2016-2018,with a distance of 0.84km.Through the area of radar map to the direction of metropolitan area in 2012-2018 the city were analyzed,and found that the main development direction of zhengzhou city to the southeast,kaifeng is mainly to the west development,and the development strategy of zhengzhou-kaifeng integration,xinxiang,jiaozuo,and the authors also towards the orientation of the zhengzhou expanding,with the government’s proposed "a nuclear,four axis,three belts,multipoint" spatial pattern.(3)Spatialization of GDP23 based on NPP/VIIRS and POI data:From two dimensions of time and space,the simulation accuracy of high-precision grid model based on NPP/VIIRS and POI data based on entropy weight assignment and spatial distribution of surrogate data is higher than that of power function model established by DNMean alone.From 2012 to 2018,five prefecture-level cities in Zhengzhou metropolitan area presented a speckle-like distribution over time.The closer to Zhengzhou,the higher the speckle-like density was,and gradually formed an economic belt leading to Zhengzhou from all directions.The economic development level of Zhengzhou is much higher than that of the other four cities,and this economic difference is reflected both among cities and within cities.On the whole,Zhengzhou metropolitan area conforms to the theory of growth pole,that is,the development pattern from point to economic axis and then to network.The NPP/VIIRS data is more suitable for the spatial simulation of GDP in larger regions,regardless of the time dimension or the space dimension.NPP/VIIRS and POI are more suitable for the spatial simulation of GDP in small and medium-sized regions.