Monitoring Singapore's microclimate

The thermal waveband of LANDSAT's Thematic Mapper satellite data can be used to gather information about the urban climate of tropical cities and, in particular, to show vegetation's influence on the living environment. This article describes how thermal data from Singapore were integrated with other data in a geographic information system (GIS) to model climatic factors in the island's rain forested nature reserves and to map "hot spots' in high-density residential estates. The GIS-based approach to mapping surface temperature permits discrete, selected temperature classes to be visualized against known surface features and land-cover types. The high correlation between surface temperature and biomass was surprising in view of the heterogeneity of the land-cover classes in housing estates, in relation to the original 120-meter resolution of the sensor, and could only have been achieved using the enhanced resolution surface temperature values. Surface temperatures observed in the present study appear to be site specific; steep temperature gradients are found across land-cover boundaries. The low wind speeds common in Singapore suggest a close relationship between surface temperature and air temperature, emphasizing the need for the evaporative cooling effect of vegetation canopies. -from Author