A numerical modelling approach
Funded by PROCORE-RGC Research Grant, Research Grant Council, Hong Kong
Examples of urban canopy models with different levels of complexity.
Numerical models are powerful tools that enable the quantification of climate conditions over cities for future or hypothetical scenarios. Such information is crucial for environmental risk assessments, heat-health impact studies, strategical urban planning, and climate change mitigation. The objective of this study is two-fold: to improve the performance of fine-scale urban climate simulations for high-rise high-density cities using Hong Kong as a case study, and to examine the effects of different urban development scenarios on the city’s urban climate and provide practical recommendations for urban planning.
Mesoscale atmospheric models are suited for simulating the meteorological conditions over the scales of cities to countries. Urban canopy models of different complexities are often coupled to represent the unique surface characteristics and geometrical features of urban areas, depending on the purpose of study, precision of surface input data, model compatibility, and available computational resources. In this study, a new multi-layer coupling approach between the mesoscale model MesoNH and urban canopy model TEB is developed. This allows the direct interaction between tall buildings and the atmosphere, notably the drag effects on air flow and thermal effects due to heat release at high levels. Furthermore, a detailed urban surface database, constructed based on real building data, land use maps, and the field mapping of representative building types, is employed to achieve the best-possible model performance. An initial evaluation of this enhanced model using measured data from the Hong Kong Observatory shows significant improvements in all important meteorological variables, such as air temperature and wind speed.
The objectives of the present study are:
To downscale global climate data to urban scale for weather information services and health impact assessment;
To develop a mitigation action plan with better urban planning and building design under extreme weather
To develop an adaptation action plan for supporting services to increase the resilience of elderly people to extreme weather.
Tall buildings in Hong Kong which interact with multiple levels of an atmospheric model (Source: SCMP).