Investigation Of Urban Heat Island Using Remote Sensing In Guangzhou

The urbanization brings a series of environmental issues to city, while bringing the enormous progress and highly material civilization. The fast development of the urbanization makes the city land coverage and utilization change enormously, and causes the urban heat island effect aggravate, which threaten the city environment and the urban crowd, so it is very important to study the relationship between urban heat island and land coverage and utilization. The urban heat island effect is a more obvious byproduct brought by the urbanization process. With urban population increase and city expand, the city land coverage and utilization changes, and then this influence the urban heat island.The traditional method to research urban heat island is mainly to utilize the meteorological observation data, its cost is relatively high and temperature spatial resolution is relatively low, so it can not reflect the state of the urban heat island in an all-round way. Remote sensing can obtain surface brightness temperature and land cover information in a large areas simultaneously, thus it can study the urban heat island effect better.Guangzhou is regarded as the center city of Zhujiang River Delta, it also is the city carried on reform and opening-up firstly in China. The rapid development of Guangzhou within nearly decade affects urban climate. This thesis investigates the relationship between the urban heat island and the land coverage and utilization during 1990 to 2002 of Guangzhou using remote sensing image, GIS (Geographic Information Systems) and statistics analytical method. The main conclusions are as follow:1. Compared retrieval surface brightness temperature image in 1990, 2000 and 2002, it can find that high brightness temperature areas increased as the year increased. Among them, the increasing amount was the most from 1990 to 2000, and slowed down to some extent from 2000 to 2002. The high-temperature areas mainly centred in Luogang District and Yuexiu District in 1990, the heat island effect was very obvious. The mass of high brightness temperature areas in Luogang Distrinct disappears basically in 2000 for government carrying on greening. The high brightness temperature areas originally concentrated in Yuexiu District in 1990 spread to the other districts, it mitigated the heat island effect to some extent. The high brightness temperature areas were broken up in 2002, it demonstrated that the heat island effect is restrained effectively.2. The vegetation cover ratio and the brightness temperature deviation value of every district in Guangzhou in different years were investigated. Comparing the three years vegetation cover ratio of study areas, it concludes that the vegetation cover ratio was decreased by 7% from 1990 to 2000 due to the city rapidly development, however, it increased 3% from 2000 to 2002. The district mean brightness temperature deviation value was positively correlated with the vegetation cover ratio and the correlation coefficient is -0.86. Comparing the district mean brightness temperature deviation values in different years, it concludes the brightness temperature deviation value of Yuexiu district is the highest in 1990, however, it decreased in 2002 due to the vegetation cover ratio increase in the last two years. In 2002, except Luogang and Baiyun have lower deviation value, five districts have the similar mean brightness temperature deviation value, and so the difference of heat island intensity between them is not significant.3. G1029 station is the constant low temperature centre and G1001 and G1044 station is the constant high temperature centre. The impervious coverage ratio of G1001 is the highest and the vegetation coverage ratio of G1029 is the highest in all 28 stations. The effect of land cover types to heat island effect is comparatively obvious at night than in daytime. It shows that the heat island effect at night is relatively intense. Surface temperature is relate to land cover types, The higher impervious coverage ratio will cause the temperature of these areas rise and become the high temperature centre; the higher vegetation coverage ratio will cause the temperature of these areas reduce and become the low centre. This phenomenon is more obvious in the evening. The high temperature centre correlates with high impervious coverage ratio, on the contrary, the low temperature centre correlates with higher vegetation coverage ratio.