The effect of background wind on summertime daily maximum air temperature in Kowloon, Hong Kong

Abstract

The increased intensity of extreme weather events (e.g., heatwaves) that is predicted to occur due to global climate change could significantly impact human health, biodiversity, and infrastructure integrity in cities. As one of the most densely constructed cities in the world, Hong Kong has been experiencing increasingly intense heatwaves in recent years. However, the city presents a challenging site for studying urban climate due to its complex topography. Using observed weather data for clear summer (June to August) days from 2000 to 2020, we examine the relationship between background wind and daily maximum temperature in Kowloon, Hong Kong, and investigate how this relationship is affected by geographical location, land cover, and topography. We reveal the distribution of near-surface wind fields under calm weather conditions, which provides a basis for the analysis of relationship between background wind and maximum temperature in urban areas under windy conditions. We find that the maximum surface air temperature in coastal regions is significantly influenced by the background wind direction. For weather stations located in the Kowloon Peninsula, a larger background wind speed is associated with a faster increase in daily maximum temperature when the background temperature rises. We find that the mountain warming effect is influential in areas at the foot of a mountain, even though the maximum terrain height is only approximately 500 m a.s.l. These findings on the daily maximum temperature behavior under different background wind conditions provide a possible way to predict extreme high-temperature patterns in different regions of Hong Kong.