Quantitative Estimation Of Land Surface Parameters And Their Applications In Urban Thermal Environment Studies

Biophysical descriptors (i.e., Land surface temperature, vegetation abundance, impervious surface, albedo and vegetation index) play a key role in global energy circulation, climatic change and energy balance studies, so their retrieval study is becoming one of the focuses of quantitative remote sensing. In addition, with the rapid development of economy and urbanization in our country, the natural landscape is transformed to anthropogenic urban land, and urban heat island (UHI) has attracted increasing attention. Furthermore, as is explored in previous researches, UHI effect is closely relate to land surface biophysical descriptors listed above. However the accuracy of estimating land surface parameters need further improved and the relationships between LST and these parameters have not been fully understood.Fuzhou was chosen as our study site, the LST and brightness temperature were estimated form both ASTER images acquired on April 6, 2004 and TM image collected on June 15, 1989. Then the linear spectral unmixing model was used to estimate the vegetating abundances and percent impervious surface from ASTER images, which had been applied C terrain correction previously. Subsequently the NDVI image was also calculated using reflectance data of TM and ASTER images.With the inversion of land surface parameters mentioned above, the relationships between LST, vegetation abundance, percent impervious surface and NDVI were analyzed.Results showed that the linear correlations between LST and these parameters were not straightforward for all land-cover types, whereas a very strong linear relationship (R~2 >0.93) was shown between the mean-LST, vegetation abundance and percent impervious. To acquire a better result, the differences between LST and brightness temperature were examined and the improved method was used to determine the scopes of UHI, the results told that the mean-standard variance method is more suitable for this study. Based on the researches discussed above, the spatio-temporal characteristics of UHI in Fuzhou from 1989 to 2004 were analyzed using landscape indices and spatial statistics technologies. Results indicated that after 15 years, the area of UHI was significantly enlarged and the urban heat intensity was also augmented, moreover, the standard deviation ellipse indicated that the center of UHI was moved towards southeast.