TROPICAL GEOGRAPHY ›› 2017, Vol. 37 ›› Issue (2): 269-276.doi: 10.13284/j.cnki.rddl.002933

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Analysis of the Correlation between Air Temperature and NDVI Cohesion Density Using Geographically Weighted and Ordinary Least Square Regression Models

XU Jianhui1,ZHAO Yi2,3,ZHONG Kaiwen1,RUAN Huihua4,SUN Caige1,3   

  1. (1.Guangzhou Institute of Geography//Key Laboratory of Guangdong for Utilization of Remote Sensing and Geographical Information System//Guangdong Open Laboratory of Geospatial Information Technology and Application,Guangzhou 510070,China;2.Guangzhou Institute of Geochemistry,China Academy of Sciences,Guangzhou 510640,China;3.University of Chinese Academy of Sciences,Beijing 100049,China;4.Guangdong meteorological observation data center,Guangzhou 510080,China)
  • Online:2017-03-05 Published:2017-03-05

Abstract: To study the influence of the spatio-temporal pattern of normalized difference vegetation index (NDVI) on air temperature in Guangzhou city, four seasons data of MOD13A3 monthly NDVI and monthly data of average air temperature in 2015 are used in this study. The distance-weighted NDVI cohesion density is calculated with MOD13A3 monthly NDVI, which indicates the synthetic information of construction land, vegetation, and waters. The central regions, Panyu and Nansha in Guangzhou city, have low NDVI cohesion density, while other regions with high-density vegetation have high NDVI cohesion density. Based on four seasons’ data of NDVI cohesion density and air temperature, this study quantitatively evaluates the correlation between air temperature and NDVI cohesion density using the geographically weighted regression (GWR) and ordinary least square regression (OLS) models. The GWR and OLS models are then established with NDVI cohesion density and air temperature. The results of GWR and OLS models are evaluated with AICC information criterion, goodness of fitting, and Sigma indexes. As compared with OLS model, GWR shows a much better fitting result, the minimum goodness of fitting increases from 0.02 to 0.464. The maximum goodness of fitting in GWR model reaches 0.724. The Moran’s I value of residual from GWR is much less than that from OLS. The Moran’s I values from OLS are 0.383, 0.342, 0.370, and 0.204 in four seasons, respectively. However, the Moran’s I values from GWR decrease to 0.022, -0.002, -0.022 and -0.025, respectively. Four seasonal Moran’s I values of residual from GWR approach 0, which indicates that the residual from GWR has no spatial autocorrelation. The relationship between NDVI cohesion density and monthly average air temperature has a significant spatial heterogeneity. In general, regression coefficients of NDVI cohesion density increase gradually from negative to positive values from north to south in Guangzhou city. The negative regression coefficients mainly exist in Huadu, Zengcheng, Conghua and Huangpu regions. The negative regression coefficients show a negative influence of NDVI cohesion density on air temperature, while the positive regression coefficients show a positive influence. In those regions dominated by the impervious surfaces, the GWR model has lower goodness of fitting, with the goodness of fitting less than 0.20. Conversely, the GWR model results are in high fit degree in other regions dominated by vegetation, with the goodness of fitting larger than 0.30.

Key words: Guangzhou, air temperature, Normalized Difference Vegetation Index, cohesion density, Geographically Weighted Regression model, Ordinary Least Square regression model