The Analysis of Utilizing Urban High-Density Street-level Air Temperature Observation Networkto Analyze the Urban High Temperature Changes with Different Geographical Environment Features

Under climate warming, urban areas with concentrated populations and high-density development are facing the challenge of increasing temperature. Due to Taiwan’s diverse geographical environment, the features of the urban heat island effect are affected by various geographical factors. It is necessary to rely on long-term observational climate data in order to present the complex urban microclimate changes. This study aims to identify hot spots in urban areas, comprehensively compareing the impact of different geographical environmental features on urban heat islands, and establish predictive models and adaptative strategies.

Our research team established a high-density street-level air temperature observation network (HiSAN) in Taiwan cities such as Taipei, Taichung, Tainan and Kaohsiung to collect hourly temperature data at the urban block scale from 2020 to 2023. Through these data, a comparative analysis of the heat island effect is carried out, taking into account the geographical features of each place, such as basins and sea-land breezes, and visualizing them with climate maps. The study found that, in summer, Taipei often experiences temperatures 2-3°C higher than surrounding areas, as the basin topography restricts air circulation, leading to the accumulation of warm air in the city which exacerbates the heat island effect. Taichung city demonstrates a relatively uniform temperature distribution and maintains temperatures 1-2°C above suburban averages. Tainan city’s temperatures are approximately 2°C higher than suburban averages. In Kaohsiung City, the urban temperatures often 3-4°C higher than suburban areas, especially in central areas, with high building density and less green space, the urban heat island effect is most obvious.

The research results also show that the heat island effect in Taipei and Taichung is closely related to the topography of their basins, while Tainan and Kaohsiung are more affected by sea-land breezes. The terrain features of Taipei and Taichung urban areas cause the urban heat storage area to be located in the basin; while the terrain of Tainan and Kaohsiung urban areas is flat, the urban heat island phenomenon is affected by the distance from the sea (sea-land breeze), and the heat island center moves significantly during the day and night. The high-density street-level air temperature observation network system contributes to urban microclimate research. It also helps to identify hot spots in urban areas, and provides useful information in analyzing the temperature and outdoor human thermal comfort of local climate zones in cities and surrounding areas. The research results also provide important references for urban planning and climate adjustment.

Keywords: urban heat island, geographical environment features, sea-land breeze, high-density street-level air temperature observation network