基于大涡模拟的冬奥赛区风环境精细化评估

Refined Assessment of Wind Environment over Winter Olympic Competition Zone Based on Large Eddy Simulation

风是北京冬奥会场外赛事考虑的首要气象因素,精细评估竞赛场地核心区域风环境对赛道施工建设、遴选防风方案及赛事安排非常必要。以北京冬奥会延庆赛区为中心,将2009—2021年冬奥赛事月份(2—3月)天气环流场进行客观天气环流分型(分为93组),采用北京城市气象研究院睿图-大涡模式系统对各组的典型个例开展37 m×37 m分辨率风场模拟。利用赛道周边12个自动气象站数据检验结果显示:2 m温度、10 m风速和风向平均偏差分别为0.45℃,1.51 m·s^(-1),11.23°,预报技巧较高。基于分型模拟数据获得赛场平均风、极大风分布及大风风险概率,高山滑雪赛场赛道起点平均风速为15 m·s^(-1),超出影响决策点概率为60%,风险较大;而赛道中、后段风险较小,超过影响决策风速概率小于2%。

The near-surface wind field over complex terrain is highly non-uniform due to the influence of topographical fluctuations.Therefore,it is extremely difficult to carry out high-density observational experiments and refined assessment of wind environment in these areas.In this case,high-resolution wind field data from numerical simulations is essential for the evaluation and analysis of near-surface wind environment.A refined wind environment assessment is carried out for Xiaohaituo alpine skiing field,Yanqing competition zone of Beijing Winter Olympic Games.Firstly,the weather patterns over the alpine skiing field during the winter competition periods from 2009 to 2021(every February and March) are divided into 5 main types according to the Lamb-Jenkinson(L-J) atmospheric circulation classification scheme,and further classified into 93 secondary circulation types according to the wind directions and speed at 700 hPa.Secondly,the coupled model system of mesoscale meteorology and large eddy simulation(RMAPS-LES)developed by Beijing Institute of Urban Meteorology is used to simulate the wind field at a horizontal resolution of 37 m for typical cases under 93 weather patterns.The comparison between the simulation results and observations at 11 automatic weather stations shows that the model simulation performs reasonably well.The results show that the average deviation of 2 m temperature is less than 2℃,which perfectly meets the accuracy requirements of weather forecast service demand.Although 10 m wind speed is slightly overestimated for the whole typical cases of different weather patterns,the average deviation is within 3 m·s^(-1),and the average deviation of 10 m wind direction simulation is 10.43°-12.36°,which shows a good prediction skill.Finally,based on the wind field simulation results of different weather patterns,a tenyear winter wind environment assessment is carried out to provide detailed spatial distribution characteristics of the wind field,risk ranges,locations of gale,and the risk probability of exceeding the wind speed thresholds of the sport events,so as to provide technical supports for the organization,time arrangement,track design and wind hazard protection of 2022 Beijing Winter Olympic Games.The method provides an effective way for wind energy assessment and forecast over complex terrain,as well as meteorological services for wind-sensitive activities,such as outdoor mega-events over complex terrain,small-scale environmental design for large-scale architectural complex over mountain terrain,mountain fire disaster prevention and mitigation,mountain pollution forecasting and nuclear proliferation assessment.