Thermal Environment Detection In The Pearl River Delta Area By Remote Sensing And Analysis Of Its Spatial And Temporal Evolutions

Land surface temperature (LST) is a main factor reflecting the ground thermal environment, which has close relationship with people's life for it influences the urban heat island effects (UHI), global warming and the energy change between ground surface and bottom atmosphere. The LST of Pearl River Delta area was retrieved by using thermal remote sensing technology. The spatial distribution, temporal development and change analysis of LST in this area were discussed from the whole and local points of view, summarizing the UHI characteristics of capital and centric cities in this area.The high temperature area and UHI intensity are two important characters reflecting the ground thermal environment. In the dissertation, a robust statistical method was proposed to divide the LST into 3 scale regions: high temperature area, normal temperature area and low temperature area. Besides marking off the high temperature area and low temperature area, this method could also eliminate the difference caused by time. The average difference between high temperature area and low temperature area was considered as the UHI intensity to quantify the fierceness of UHI. Ten cities almost lying in the same latitude were selected to analyze the relationship between UHI characteristics and physiognomy factors like urban size, development area, vegetation abundance and water ratio, and human factors such as population density. The results show that the city of Guangzhou has the strongest UHI intensity as much as 5.8℃, while the Boluo county has the lowest UHI intensity with value of 3.1℃. Correlation analysis shows that three factors: urban size, development area and population density have the closest relationship with the UHI characteristics.As far as the spatial distribution of LST is concerned, the high temperature area in this area was mainly along the urban-used land. The comparative analysis to the LST ofthe two banks of Pearl River Delta shows that there are different increases in area for the high temperature area with 93.8% for east bank and 17.5% for west bank compared with the year of 1990. For the average temperature of the two banks, there are almost no difference in 1990, but the average temperature in the east bank was 1.5 °C higher than that of west bank in 2000. The LST difference of two banks may also reflects the different policies of the government in the two banks. The analysis to the components of the high temperature area show that the urban-used land and the bare land are the main land covers constituting the high temperature area with 77.5% and 88.9% respectively for the year of 1990 and 2000. From the temperature range of different land covers, more than half of the urban-used land locates in the high temperature area. There are also considerable parts of development land, sand land and bare land lie in the high temperature area, while most of the other lands are belonging to the low temperature area.A land use evolvement flowchart was deduced by the research on the land use change analysis. The LST of different land covers were calculated, based on which the LST changes caused by land use change were analyzed and made a LST transfer table. From the LST transfer table and land use evolvement flowchart, the reason of the increase of the LST high temperature area was analyzed.The relationship between LST and climate was also studied by studying on the temperature change of Guangzhou in the recent 50 years. The study on the relationship between LST and air temperature shows that there is no direct linear relationship between them. The fluctuating temperature of land surface was larger than that of the air. The comparison of LST and the air temperature in the same place shows that different places are different. Usually, the LST are higher than air temperature in urban-used land and development land. On the contrary, the LST are lower than air temperature in dike-pond, cropland and water area.Compared with the previous researches, many innovative ideas were presented, including (1) dividing the LST into three scale ranges: high, normal and low temperature area, by using a robust statistical method, which method was proposed at the first time and eliminated the impacts of uncertain factors like time;(2) a method to calculate the UHI intensity;(3) giving the land use evolvement flowchart and temperature transfer matrix in the Pearl River Delta area from 1990 to 2000;studying on the relationship between land surface temperature and air temperature.