Recently, Tibetan plateau (TP) has become a hot area of climate change research. And Land Surface Temperature (LST) is one of key factors in the research. In order to get a long time-series, high spatial resolution and high accuracy LST dataset, we carried out analysis of influence essential factor of LST retrieval from AVHRR oriented Tibetan plateau area. First, choose MODTRAN5.2 to simulate the impact of land surface, atmospheric, geometric factors on bright temperatures of channel 4 and channel 5 for special features of TP using stand atmospheric models. Result showed that emissivity, boundary temperature, water vapor amount and view zenith angle were the principal elements of bright temperature. Second an improved algorithm from Wanz-Dozier split window model was established considering these factors. At last, differences between LST retrieval result considering different factors were given.
This study explores a spatiotemporal comparative analysis of urban agglomeration, comparing the Greater Toronto and Hamilton Area (GTHA) of Canada and the city of Tianjin in China. The vegetation–impervious surface–soil (V–I–S) model is used to quantify the ecological composition of urban/peri-urban environments with multitemporal Landsat images (3 stages, 18 scenes) and LULC data from 1985 to 2005. The support vector machine algorithm and several knowledge-based methods are applied to get the V–I–S component fractions at high accuracies. The statistical results show that the urban expansion in the GTHA occurred mainly between 1985 and 1999, and only two districts revealed increasing trends for impervious surfaces for the period from 1999 to 2005. In contrast, Tianjin has been experiencing rapid urban sprawl at all stages and this has been accelerating since 1999. The urban growth patterns in the GTHA evolved from a monocentric and dispersed pattern to a polycentric and aggregated pattern, while in Tianjin it changed from monocentric to polycentric. Central Tianjin has become more centralized, while most other municipal areas have developed dispersed patterns. The GTHA also has a higher level of greenery and a more balanced ecological environment than Tianjin. These differences in the two areas may play an important role in urban planning and decision-making in developing countries.