2.3 Derivation of LST from Landsat TM/ETM+ imagery
The LST were derived from the corrected TM/ETM+ TIR band.
The local time of satellite overpasses was in the morning
(approximately 11:00 AM) (this was the best image available),
so that the chance for detecting a weaken UHI is maximized.
The following equation was used to convert the digital number
(DN) of Landsat TM/ETM+ TIR band into spectral
radiance[12].For Landst-5 TM, Chen at al proposed a method
of deriving brightness temperature. First, the digital numbers
(DNs) of band6 are converted to radiation luminance
(
6 TM R
, ) by the following formula: