An approach to examining performances of cool/hot sources in mitigating/enhancing land surface temperature under different temperature backgrounds based on landsat 8 image

Numerous studies on urban heat island (UHI) effects have examined relationships between land use/land cover (LULC) and land surface temperature (LST), while impacts of environmental temperatures on these relationships have received little attention. This paper has investigated how background temperature affects performances of cool/hot sources in either enhancing or mitigating LST in Shenyang, China based on Landsat 8 image. In specific, according to the method of standard classification method with an interval of 1.0 standard deviation, LST was classified into seven temperature levels: highest, higher, high, medium, low, lower and lowest. Afterwards, the seven levels were merged into three temperature zones (TZ), namely cold TZ (CTZ, highest, higher and high), neutral TZ (NTZ, medium) and hot TZ (HTZ, low, lower and lowest), for investigating relationships between LST and LULC (including building (BU), road (RO), bare land (BA), green land (GR), agricultural land (AG) and water bodies (WA)). LST generally follows the order of BU > RO > BA > AR > GR > WA, but temperature differences between cool/hot sources reduce as background temperature increases. LULC-LST relationships vary greatly with background temperature. Overall, BU and RO have significant positive relationships with LST, while negative relationships are found among GR, AR, WA and LST. However, in CTZ, RO is in negative relationships with LST, GR and WA are no longer significant in NTZ, and GR and BA play significant positive roles in aggravating LST in HTZ. Generally, this study can help orientate scientific decisions in urban environmental governance.