The urban heat island in Hong Kong: Causative factors and scenario analysis

Although many methods for heat island study have been developed, there is little attempt to link the findings to actual and hypothetical scenarios of urban developments which would help to mitigate the UHI in cities. The aim of this paper is to analyze the UHI at sites with different geometries, land use, and environments within Hong Kong, with emphasis on the influence of different geometric and environmental parameters on ambient air temperature. In order to evaluate these effects, the parameters of (i) Air pollution (AOT), (ii) Green space (NDVI), (iii) Anthropogenic heat (AH) (iv) Building density (BD), (v) Building height (BH), and (vi) Air temperature (Ta) were mapped. The optimum operational scales between Heat Island Intensity (HII) and different parameters were evaluated by testing the strength of the correlations for every resolution. The compromised scale for all parameters is 275 m resolution. Thus, the measurements of these parameters contributing to heat island formation over the urban areas of Hong Kong were established from mathematical relationships between them and in combination at 275 m resolution. The mathematical models were then tabulated to show the impact of different percentages of parameters on HII. These tables are useful to predict the probable climatic implications of future planning decisions.