Environmental Challenges (Apr 2023)
Assessment of urban green areas towards changing surface energy balance fluxes in tropical study sites, Central Thailand
Abstract
The surface energy balance is broadly accepted as the interaction of the available energy fluxes that leads to the evaporation of surface water and an increase or decrease in the temperature of the surface and pertinent environment. This concept is widely utilized, shifting the increasing urbanization towards sustainable cities on a scientific basis for the planning and management of urban areas. Understanding the ambient factors governing energy fluxes will help mitigate the environmental burden linked to climate change by optimizing the layout of sustainable townships. For a quantitative description, we applied the eddy covariance method, which is one of the most widely accepted methods of monitoring flux changes, at different land-usage and surface-cover locations in an urban area (Kasetsart University (KU) tower), a rural natural mangrove forest environmental system (LERD project), and a spacious urban park estate (Bangkok, Bangkajao District). The results suggested that urban land usage has led to a shift in the ratios of energy fluxes, in which the proportion of latent heat in the mangrove forest area, Bangkajao Green Urban Park, and KU tower were 41%, 29%, and 22%, respectively. However, sensible heat at the KU tower, which is located in the denser urban areas of Bangkok, was predominant at 39% of the heat flux, whereas the transfer of energy into sensible heat in the LERD project and Bangkajao was 17% and 26%, respectively. This study reveals an increase in sensible heat in urban areas and a decrease in latent heat fluxes. Measurements linked to land-use classification showed that changes in the urban structure significantly contributed to heat in the spatial and temporal scales and indicated necessary avenues for the management of urban heat islands and mitigation of related adverse effects.
