Improvement of the understanding of the 3-dimensional wind behaviors in urban areas of Hong Kong using Doppler LIDAR system (C4020-16G) (27 May 19 - 30 Jun 21)
• Researchers: NG Yan Yung, Jimmy FUNG, REN Chao, Janet BARLOW
• Funding Amount: HK$500,000
• Funding source: Research Sustainability of Major RGC Funding Schemes 2018-19

Investigating urban wind flow is crucial to understanding many aspects of healthy urban living – urban ventilation, pollution dispersion, thermal comfort, as well as to inform engineering, architecture, and planning. Very little wind data is available for many cities, due to difficulties in deployment and measurement in such a complex environment. The 3-dimensional (3D) urban wind environment of Hong Kong is complicated. The information has not been available in the past nor could be obtained in full details by wind tunnel or computational simulations. To fill the knowledge gap, we propose using the Doppler LIDAR to measure the 3D urban wind environment under different atmospheric stability conditions. Recent technological advances mean that ground-based remote sensing instruments such as Doppler LIDARs are now robust enough to conduct longer term urban studies, for example, in London. Deploying LIDARs in Hong Kong would lead to a step change in understanding about a very complex wind environment that is hard to model. The 3D wind data could provide observational dataset to evaluate the wind tunnel and CFD/LES results and eventually advance our numerical models development and understanding of the dynamical and thermal processes within the urban boundary layer. The development of the urban airflow model to drive the urban-scale air pollution model also requires knowledge of detailed 3D airflow in urban area. The dataset is also valuable for the studies of outdoor thermal comfort.

Since the Severe Acute Respiratory Syndrome (SARS) episode in 2003, there is a realization that for high density tropical urban living, a well ventilated and less polluted city is crucial for health in terms of heat stress relief, and pathogens and pollution dispersion. Based on the 3D wind dataset and modelling studies, the proposed study will provide a scientific basis for designing a better ventilated and cleaner built environment for our city residents. The first weak-wind urban Air Ventilation Assessment (AVA) System in the world was introduced to Hong Kong in 2006 by the HK Government (PlanD 2016). However, the current AVA System relies on wind tunnel and CFD results and assumes “neutral” atmospheric stability condition and thus has limitation. Our study will provide the much needed scientific and realistic basis for better AVA results for architects, planners and policy stakeholders. For air pollution and dispersion study, our study would help achieve the goal set out in the Clean Air Plan, by developing a location-aware street-scale air quality modeling system.