Impact Of Urbanization On Air Temperature Change In Pearl River Delta

Based on the homogenized observed daily air temperatures from24meteorological stations, DMSP/OLS nighttime lights image, and the NCEP/NCAR Reanalysis (R1) air temperature monthly data from1979to2010, the urbanization effect on air temperature change in the Pearl River Delta region was analyzed by two methods, urban minus suburban and observation minus reanalysis (OMR) methods. The relationship between air temperature changes and urbanization indicators were also analyzed in this paper. Main results are concluded as follows:(1) From1961to2010, the annual mean/maximum/minimum temperature of urban stations and suburban stations in the Pearl River Delta region are all on upward trends, and the increasing rate of air temperature in urban stations are faster than that in suburban stations. The annual mean temperature, maximum and minimum temperature increase at a rate of about0.12℃/10a,0.05℃/10a,0.15℃/10a, accounting for41.6%,17.4%,43.9%of the total warming, respectively. The largest upward trend of seasonal mean/maximum/minimum temperature is seen in autumn.(2) From1979to2010, the annual mean/maximum/minimum temperature increase at a rate of about0.20℃/10a,0.04℃/10a,0.22℃/10a, accounting for43.7%,8.0%,47.5%of the total warming, respectively. The largest upward trend of seasonal mean/maximum/minimum temperature is seen in autumn, and the smallest upward trend is seen in summer.(3) The OMR trends of annual mean/maximum/minimum temperature in the Pearl River Delta region are about0.22℃/10a,0.19℃/10a,0.23℃/10a, accounting for55.7%,41.7%,57.2%of the total warming, respectively. The largest OMR trend is located in Shunde, Nanhai, Panyu or Heshan which is in the central area of the Pearl River Delta, and the smallest OMR trend is located in Huidong or Shangchuan Island. The OMR trends of seasonal temperature increase significant in winter.(4) Both of the two methods show that the urbanization effect is more obvious on minimum temperature than on maximum temperature.(5) The urbanization indicators, such as urban total population logarithm, built-up area, GDP and annual energy consumption, and the annual mean temperature difference between urban and suburban, as well as the OMR of annual mean temperature, are creditable correlated.