Characteristics of Urban Thermal Environment from Satellite Remote Sensing Data in Ho Chi Minh City, Vietnam

The period of spontaneous development of Ho Chi Minh City in Vietnam has caused uncontrollably environmental problems occurred. Besides, the concrete surface caused increasing surface temperatures, reducing evaporation, consequently heating up urban space. This paper presents the results of the application of Landsat satellite images to study the urban thermal environment from the thermal infrared channel by capability of object surface emissivity for the northern part of Ho Chi Minh City. The Landsat satellite images was used for exploratory research to date 21-01-2014. The method to extract land surface temperature (LST) from thermal infrared bands with emissivity determined by the characteristics of Normalized Difference Vegetation Index (NDVI) values has created detailed results according to resolution of the reflectance bands. In addition, the relationship between the heating element and land cover variables (impervious surface, bare soil, vegetation and water) is also considered in order to find the relationship determining factor affecting the urban thermal environment. The study results showed that the developing urban area is where the high temperature exits. A giant heat island is formed on the central area of the city with temperature ranging from 32oC to 44oC and above. Besides, impervious surface is a major factor contributing in the warmth of the thermal environment in the city with the highest number of positive correlation (R = 0.87), whereas vegetation is factor that impact to reduce heat with the highest number of negative correlation (R = -0.84). In Ho Chi Minh City there is only one ground meteorological station, so its temperature number does not express the thermal environment in the whole city. These results are a good reference for local city authorities in urban spatial planning during climate change period nowadays.