Quantifying the influence of wind advection on the urban heat island

• Main Author: Bassett, Richard
• Published: University of Birmingham 2018
• Subjects: GB Physical geography
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.753132

Although the urban heat island (UHI) is well studied, the dynamic nature (i.e. with wind) receives little attention. The concept, urban heat advection (UHA), can warm air temperatures in surrounding rural areas. This may lead to a misinterpretation of local climate and bias in long-term climate records. Using observational analysis and numerical modelling this thesis investigates these limitations by spatially quantifying UHA. A methodology to separate UHA from the background air temperature was applied to a high-density urban observation network in the city of Birmingham, UK demonstrating mean downwind UHA of 0.4oC and up to 1.2oC at individual stations (wind speeds 2 – 3 m s-1). This UHA methodology was adapted to show that even small urban areas (~1 km2) can produce a mean UHA of 0.6oC. TheWeather Research & Forecasting numerical model was used to refine the UHA methodology (accounting for regional heat advection) and conduct semiidealised simulations. Here, a square city with 16 km size produced UHA of 2.4oC at the city edge, with 0.5oC warming extending 9 km downwind. A relationship was found between city size and UHA intensity, enabling statistical scaling. This demonstrated an approach to estimate UHA without the need for computationally expensive simulations.