Spatial characteristics of urban evapotranspiration effects on the thermal environment

Evapotranspiration (ET) is an important process of the regional hydrothermal cycle. However, it is unclear how the mitigation of urban ET in urban thermal environments occurs in a spatial context. Landsat 8 satellite images from 2014 to 2018 of Xuzhou and corresponding meteorological observations were selected, and the improved mono-window algorithm (IMW) and urban RS-PM model were applied to invert land surface temperature (LST) and ET, respectively. In addition, spatial analysis methods (a profile analysis, standard deviation ellipse (SDE) analysis, and bivariate Moran's I) were employed to quantify and simulate the spatial characteristics of the ET effect on LST. The results indicated the following: (1) There was a significant linear negative correlation between ET and LST, which confirms that ET has a negative effect on LST; (2) the SDE overlap ratios between patches with higher ET and lower LST imply that higher ET patches have a significant impact on the spatial distribution of LST; and (3) bivariate Moran's I between ET and LST and their linear mixture spectral analysis (LISA) maps reveal a significant negative spatial correlation between ET and LST. In addition, the landscape pattern of higher ET parches is also an important factor affecting the environmental temperature. HIGHLIGHTS A significant negative spatial correlation between ET and LST was found.; Areas with various ET intensities have different regulatory effects on LST.; Higher ET intensity is not an absolute factor in mitigating the urban thermal environment.; Landscape pattern of the patches with higher ET also has a significant impact on LST regulation.;