A Comparison Study between Local Climate Zone Mapping by GIS-based Method and WUDAPT Method

In recent years, rapid urbanization has resulted in urban climate change worldwide. The topic of the Urban Heat Island has been an especially hot topic. Local Climate Zones (LCZ), a newly developed concept, aims at linking different land cover types to corresponding thermal properties directly, and thus provides a standard for scholars from different regions to study urban climate ^[1]. There are two main methods for mapping Local Climate Zones (LCZ): one is a GIS-based method, and the other is a satellite image based method called the World Urban Data Access Portal Tool (WUDAPT). The former calculates contributing parameters of LCZ classes (like building height, sky view factor, building surface fraction and so on) to generate LCZ maps, while the latter depends on free satellite images (such as Landsat8) to conduct LCZ mapping with the assistance of machine learning algorithms on open-source SAGA GIS.

Although many LCZ maps have been produced by these two methods, there exist few studies comparing the two. The study area for this report will be Hong Kong. This offers two major advantages: because most of LCZ classes can be found in Hong Kong and all the required data for both methods are available in the city. This paper attempts to evaluate the reliability of these two methods.

The comparison between the two methods will focus on their LCZ maps. First, the spatial distribution and patterns of each LCZ class will be discussed in comparison with the real urban morphology of Hong Kong. Second, parameters such as building height and impervious and pervious surface fractions will be extracted from the LCZ map generated by the WUDAPT method, and then compared with the corresponding values calculated in the GIS-based method.

Keywords: Local Climate Zone; comparison; GIS; WUDAPT

Reference:

[1] Stewart, I. D., & Oke, T. R. (2012). Local climate zones for urban temperature studies. Bulletin of the American Meteorological Society, 93(12), 1879-1900.