Assessment of landscape patterns affecting land surface temperature in different biophysical gradients in Shenzhen, China

The urban heat island (UHI) effect is one of the important ecological effects of urbanization. This study focuses on the different effects of landscape patterns on LST within different land covers. The land cover was measured by surface biophysical components, including vegetation fraction (VF) and impervious surface area (ISA), acquired by a linear spectral mixture model (LSMM). LST was derived from Landsat-5 TM thermal infrared (TIR) data using the generalized single-channel method. Landscape patterns were measured by landscape metrics, including the Shannon diversity index (SHDI), the aggregation index (AI), patch density (PD), and fractal dimension area-weighted mean index (FRAC_AM). Shenzhen, a rapidly urbanizing city in China, was taken as the case study area. Results showed that VF and ISA are more important than spatial patterns in determining LST. However, these effects change in densely covered areas. VF and LST are negatively correlated, with the inflection of the regression curves being 45 %. In areas with VF lower than 45 %, the correlation between LST and VF is monotonically linear. In areas with VF higher than 45 %, landscape patterns can act to decrease LST. The aggregation index (AI) and the largest patch index (LPI) can contribute to decreasing LST significantly. Impervious surfaces contribute to high temperature, and the inflection point of the regression curves is 70 %. In areas with ISA higher than 70 %, a fragmented pattern of impervious surfaces can lower LST. These findings provide insights for planners into how the strategic use of landscape to mitigate UHI effects may vary for different land covers.