复杂地形下冬奥古杨树赛区山谷风环流特征分析

Analysis of Valley Wind Circulation Characteristics in the Guyangshu Winter Olympics Competition Area Under Complex Terrain

关键词:  冬奥  谷风  坡风  复杂地形  冷空气

Key words:  Winter Olympics  valley wind  slope wind  complex terrain  cold air

摘要:

利用 2017—2020 年冬奥赛场加密自动站资料和 ERA5 再分析资料，通过风矢量平均法和合成分析法，从特殊地形和大气环流背景角度出发，对古杨树赛区风场环流演变特征进行研究。结果表明，古杨树赛区受地形阻挡及热力作用明显，场馆内风向风速具有明显的地形风特征差异。白天时段内风向相对分散，风速主要在 5 m·s-1以下，夜间段内风向普遍集中且风速较小，主要分布在 3 m·s-1以下；同场馆内以下坡风为主导的站点比以下谷风为主导的站点风速更小，主要在 2 m·s-1以下。弱冷空气背景下，白天转向时间在 08时前后，傍晚在 17—19 时前后，转换期时长平均在 1.5~2.0 h，转换时间先后及转换期时长明显受太阳辐射影响；风速随着风向的转变先减小后增大，冬季两项赛区在 09 时前后达到一天内最小日平均风速，12—14 时达到一天中最大日平均风速，而越野赛区一天中最大日平均风速出现在12—15时；各站点的日平均风速与其所在位置的地形风尺度有关，受谷风影响的站点风速往往大于受坡风影响的站点风速。

Abstract:

This study investigates the dynamics and characteristics of air flow in the Guyangshu competition area by analyzing intensive observation of automatic weather stations and ERA5 reanalysis data collected in the Winter Olympics field from 2017 to 2020. Considering its distinct topography and the context of atmospheric circulation, wind vector averaging and composite analysis methods are employed to improve analyses. Results indicate that the Guyangshu competition area is highly influenced by terrain and thermal effects, resulting in significant differences in terrain wind characteristics. Daytime wind directions are relatively scattered, with speeds mostly below 4-5 m · s-1. At night, wind directions are more concentrated, and speeds are generally below 2-3 m · s-1. Within the same competition venue, stations dominated by down-slope winds have lower wind speeds, mainly below 1-2 m · s-1, compared to those dominated by down-valley winds. Under weak cold air conditions, wind direction shifts typically occur around 08:00 in the morning and between 17:00-19:00 in the evening. The transition period averages 1.5- 2 hours, with the timing and duration of these changes are significantly influenced by solar radiation. As the wind direction changes, wind speeds first decrease and then increase. In the winter competition areas, the lowest average daily wind speeds are observed around 09:00, while peak average daytime wind speeds are observed between 12: 00 and 14: 00. In off-road competition zones, the highest daily average wind speeds are recorded between 12:00 and 15:00. The average daily wind speeds at each station correlate with the terrain's wind scale in their locations, with stations influenced by valley winds often have higher speeds than those affected by slope winds.