Classifying Spatial Homogeneity of Thermally-Stabilized Surface to Define Differentiation Local Atmospheric Zones in Chiang Mai City

Abstract

The aim of this research paper is to examine ways to integrated impact of the natural environment and typical urban morphological features on the thermal load into urban climate planning using spatially distributed information of local atmospheric zones (LAZs). To achieve this, the form and morphology of urban planning and their contents concerning urban heat island issues were examined in the 2557 BE summer season in Chiang Mai city area. Spatially distributed information on local atmospheric zones and their homogeneity of thermally-stabilized surface in the study area was generated using the spatial-multivariate analysis, which is an approach of urban climate analysis and evaluation tool suitable for planning purposes. The results found that the downtown-suburb continuum of local atmospheric zones with a hierarchy of 8 zones and an urban heat island intensity (UHII) can often exceed 4.35 Celsius in summer. An urban core of 20.88 square kilometer as the highly temperature-sensitive urban area is very densely built with a very high thermal load with the mean land surface temperature of 34.49 Celsius. Remedial measures and mitigation actions are urgently needed. Excessive development and construction should be strictly prohibited along the potential ventilation paths. Reasonable planning and reconstruction should improve severe urban climatic problems if possible. Building height imitations, rational spatial distribution, and controlling the aspect ratio of building height to canyon width and orientation in streets should be considered to avoid further urban environmental damage. Additional greenery and tree planting in open spaces and streets in this planning zone are strongly recommended. Moreover, greenery should be largely introduced around existing buildings, which can alleviate the thermal load and promote cool air exchange among buildings. Widening streets and preserving open space are long-term and effective measures.