Modelling and simulation of the urban heat island effect in a tropical seaside city considering multiple street canyons

For tropical seaside cities, the net advection heat flux plays a significant role in local urban heat island (UHI) formation during the nocturnal time. However, the net advection heat flux is usually neglected in conventional modelling methods. An improved urban canopy model (UCM) has been developed to simulate the UHI effect in the tropical seaside cities. The model was proposed by introducing an adaptive approach to estimate the airflow rate inside a street canyon. Furthermore, the airflows in multiple connected street canyons were also considered. The improvements of the proposed model were validated with experiments conducted in a typical tropical seaside city, Sanya, China. In summer, the maximum error between the measured data and the simulation result of the conventional model was 0.68 degrees C, which was reduced to 0.21 degrees C with the proposed model. In winter, the maximum error was reduced from 0.84 degrees C with the conventional model to 0.49 degrees C with the proposed model. The experimental studies also showed that the UHI in summer (0.5-1.1 degrees C) was greater than that in winter (0.4-0.5 degrees C). On summer nights, wind flow along the streets had a greater mitigation effect on UHI formation than that in the daytime.