Abstract: With the deterioration of urban thermal environment, the frequency of extreme heat events in cities is increasing. The conceptual planning strategy at the city scale cannot alleviate the Urban Heat Island (UHI) effectively due to the lack of practicality. However, the strategy at local scale is difficult to be put forward,sinceone of the significant reasons is lack of a standard framework for urban microclimate study. This research took Wuhan as the case study. Based on the concept of the Local Climate Zone (LCZ) put forward by OKE’s team, a workflow was proposed to optimize the urban thermal environment at local scale through quantitative measurements. Technically, we coupled Arcmap and ENVI to extract 9 land surface indicators, which are used most frequently as land surface sensitivity of Land Surface Temperature (LST), from the satellite image products of the Landsat-7 ETM+ and the shape file data of buildings in Wuhan. The K-means clustering was applied to classify LCZ based on the 9 indicators. Furthermore, the relationship between the land surface indicators and LST was analyzed using Ordinary Least Squares (OLS). Taking LCZ as the framework, the mitigation process was organized in a manner of hierarchies and priorities combined with the correlation between the land surface indicators and LST. The results show that Wuhan is divided into 7 LCZs and the hotspots with the highest temperature in each LCZ are found out. At the same time, it is discovered that the land surface indicators have unique correlations with LST in different LCZs. And it is necessary and effective to optimize the urban thermal environment of hotspot in its LCZ by adjusting the land surface parameter values. The method in this research can reduce the temperature of local UHI to a certain extent, and the contributions to the study of urban microclimate and planning are at least two aspects: 1) the study scale of the urban thermal environment is optimized; and 2) the workflow of adapting urban thermal environment is proposed from the perspective of urban planning.
Key words：heat island；climate zone；land surface temperature； local scale；hotspot