Abstract: Urban heat island effect could be felt with in karstcity,Guilin rapid expansion.After the mixed pixel emissivity of karst hills is computed,land surface temperature (LST) of the karst city could be retrieve from remote sensing image with mono-window algorithm in.Results demonstrated that the difference between the retrieved LST and measured LST is within 2 °C.LST values in the old central district are lower than those in the developing district and industrial districts.LST possesses a negative correlation with vegetation fraction as it decreases with vegetation fraction increasing.LST of water is the minimum,about17 °C.As the karst hills are vegetated,LST of the shaded slope ranges from 18to 19 °C and LST of sunlit slope from 22 to 24 °C.However,the LST range of concrete squares and large buildings is from 32 to 33 °C.As factories with the crowded buildings emit much heat,their LST values range from 33 to 36 °C,the maximum.LST values of some pixels even reach 40 °C.The vegetated karst hills show the urban cool island effect and can improve urban microclimate environment in the karst cities.

Key words: karst city, land surface temperature, mono-window algorithm, mixed pixel, remote sensing retrieval