Investigations of high-density urban boundary layer under summer prevailing wind conditions with Doppler LiDAR: A case study in Hong Kong
Investigations of high-density urban boundary layer under summer prevailing wind conditions with Doppler LiDAR: A case study in Hong Kong
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DOI：
10.1016/j.uclim.2021.100884
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发表时间：
2021-06-15
期刊：
影响因子：
6.4
通讯作者：
Ng, Edward
中科院分区：
文献类型：
--
作者：
He, Yueyang;Ren, Chao;Ng, Edward
高密度城市边界层是最复杂的大气条件之一，但由于缺乏合适的测量方法，城市高密度边界层的野外观测资料十分有限。为了更好地了解高密度城市中的UBL结构，利用多普勒风激光雷达在香港进行了一项开创性的调查。垂直风速廓线是在三个地点测量的：阿奎拉角(上风)、香港大学(市中心)和香港科技大学(下风)。为了应对夏季的弱风条件，选择盛行的西南风条件作为调查对象。根据观测，香港上空的梯度高度约为1.0-1.2公里。在此高度以下，垂直风速廓线明显受地表地形的影响。幂定律方程对上风(α=0.1-0.15)和下风(α=0.27)剖面进行了适当的参数化，但在对市中心剖面进行参数化时有一定的局限性。揭示了常规中尺度数值模拟和风洞试验所预测的垂直风速廓线的不足。这些结果为研究人员和工程师提供了基准数据，以完善他们的城市气候预测。它们概括了对UBL气候的更好理解，这可以与其他高密度城市分享。
The high-density urban boundary layer (UBL) is one of the most complex atmospheric conditions, while the field data of UBL is limited due to the lack of suitable measurement methods. To better understand the UBL structures in high-density cities, a pioneering investigation is conducted in Hong Kong by Doppler wind LiDAR. Vertical wind speed profiles are measured at three locations: Cape D'Aguilar (upwind), University of Hong Kong (downtown), and Hong Kong University of Science and Technology (downwind). To address the weak wind conditions in summer, the prevailing southwest wind condition is selected as the subject of investigation. Based on the observations, the gradient height over Hong Kong is approximately 1.0-1.2 km. Below this height, the vertical wind speed profiles are significantly modified by surface morphologies. The power-law equation appropriately parametrizes the upwind (alpha = 0.1-0.15) and downwind (alpha = 0.27) profiles, but it has limitations when parametrizing the downtown profile. Deficiencies of the vertical wind speed profiles predicted by conventional meso-scale simulations and wind-tunnel experiments are revealed. These results provide researchers and engineers benchmarking data to refine their urban climate predictions. They generalize a better understanding of the UBL climates, which can be shared with other high-density cities.