Comparison of satellite measured temperatures using Terra ASTER and Landsat ETM+ data

The at-sensor brightness temperatures measured by Terra ASTER and Landsat ETM+ and the surface temperature of ASTER were compared to one another in the study. The study area is located along the east coast from southern Virginia to the north of North Carolina, USA. Data sources consist of two adjacent pairs ASTER and ETM+ scenes, both acquired on the same day. All data were first converted to the physical temperature in degrees C, together with other necessary preprocesses before comparison. Results indicate that minimum, maximum, mean, and standard deviation of the at-sensor temperatures of these two sensors are very similar. Strong linear correlations (R²>0.99) were found between surface temperature and mean at-sensor brightness temperature for ASTER. However, inter-sensor comparison of measured temperatures, though overall still showing high correlation with R² values between 0.85 and 0.95, presents regular vertical columns in each scatter plot, and the variation range reached by these columns could be up to 10degC or more, which indicates that for different locations the temperatures measured by ETM+ may be the same but the corresponding temperatures measured by ASTER may vary by up to 10degC or more. This may suggest that there is some poor performance in Landsat-7 band 6 and warrants caution in applications when Landsat ETM+ thermal imagery is involved