Improvement of the Understanding of the 3-Dimensional Wind Behaviours in Urban Areas of Hong Kong using Doppler LiDAR System (C6026-22GF) (30 Jun 23 - 29 Jun 26)
• Researchers: Jimmy FUNG, NG Yan Yung, REN Chao, Janet BARLOW and Ewan O'CONNOR
• Funding Amount: HK$7,124,940
• Funding source: Research Grants Council - Collaborative Research Fund 2022/23

Designs to provide better urban ventilation improve the living environments of cities. As cities densify, the need for a better scientific and practical understanding of urban wind environments is paramount. Hong Kong (HK), which is located in a subtropical climate zone with hot and humid summer months, has one of the highest living densities in the world. In 2006, the HK Planning Department (PlanD) established the Air Ventilation Assessment (AVA) methodology for stakeholders to conduct studies and optimize designs.

Currently, a territory-wide wind profile dataset, generated using the Regional Atmospheric Modelling System, is available on the PlanD website. This dataset has never been validated using field observations. Recently, the building effect parameterization (BEP) /building energy model (BEM)-coupled Weather Research and Forecasting (uWRF) model was used to provide input wind profiles to AVA studies. However, this model also lacks long-term field data to validate the parameterizations of surface momentum flux. As the AVA results depend heavily on input wind profiles, it is important to fill the above knowledge gap.

Doppler light detection and ranging (LiDAR) was recently developed to measure wind profiles with high temporal resolution and stability. Although some case studies have been conducted, an annual spatial understanding of wind profiles in a high-density urban setting is still lacking . The proposed project has four objectives:

(1) Using LiDAR on-site measurement, observe the vertical wind environment in high-density cities (HK as an example), as well as reveal the scientific merit/gaps of the existing modelbased knowledge on vertical urban wind profiles;
(2) Using results of Objective 1, improve the current scientific understanding to optimize the numerical parametrization schemes of the mesoscale meteorological model (e.g., uWRF model), as well as produce a spatial map of urban wind profiles for HK;
(3) Using results of Objectives 1 and 2, improve the current model understanding to optimize the selection and setting of the inflow boundary and thermal conditions in the microscale Large Eddy Simulation models, as well as improve the study results of urban winds in high city density settings;
(4) Using results of Objectives 2 and 3, improve the practice understanding of PlanD’s AVA methods, and knowledge transfer to industry-stakeholders.

An improved scientific and practice understanding of wind profiles and the urban wind environment in a high-density city is of reference value to the LiDAR research community. It will allow better planning decisions to be made to improve the city’s living environment.