冬奥崇礼赛区一次冷湖过程形成及消散的数值模拟研究

本文利用中尺度数值预报模式（WRF）并采用谱逼近方法，对2021年冬奥测试赛期间的一次冷湖过程进行模拟研究，探究了冷湖发展前后风温场的垂直变化规律，揭示了冷湖形成及消亡的具体原因。研究结果表明，静稳的天气形势是冷湖过程维持及发展的大背景条件。冷湖发展期间，逆温层由上至下迅速建立，谷底出现偏东—东南向的冷径流。受重力下坡风的影响，冷空气不断向谷底堆积，冷湖深度增加。日出后，越山的系统风重新建立，逆温层从底部消蚀，冷湖结构破坏。夜间的强辐射冷却作用是冷湖形成的主要原因之一。辐射冷却强度的差异会引起冷湖降温幅度的差异，后半夜辐射冷却作用的突然加强为冷湖中后期的维持及发展创造有利条件。通过分析冷湖发生前后位温廓线、摩擦速度及边界层高度随时间的演变，均可印证湍流活动的发展是逆温消散、冷湖结构破坏的重要影响因素。

Numerical Simulation of the Formation and Dissipation of a Cold Air Pool in the Chongli Winter Olympic Games Area

Based on the mesoscale regional numerical model (WRF) and a spectral nudging method, this study simulates a cold air pool (CAP) process during the 2021 Winter Olympics test competition. The vertical change in the wind and temperature fields during this process has been analyzed, and the specific reasons for the formation and dissipation of the CAP have been demonstrated. The results show that the stationary synoptic situation formed the general background for the maintenance and development of the CAP. During the development of the CAP, a temperature inversion layer was rapidly established from top to bottom, and a southeast cold air flow appeared at the bottom of the valley. Affected by the downward gravitational wind, the cold air accumulated at the bottom of the valley, and the CAP deepened. After sunrise, the mesoscale winds over the mountain were reestablished. The temperature inversion layer was eroded from the bottom, and the structure of the CAP was destroyed. Strong nocturnal radiation cooling was the main reason for the formation of the CAP. Differences in the intensity of radiation cooling cause differences in the cooling range of the CAP. Sudden enhancement of radiational cooling after midnight created favorable conditions for the maintenance and development of the CAP in the middle and later periods. Through analysis of the evolution of the potential temperature profile, friction velocity, and boundary layer height during the process, it can be confirmed that the development of turbulent activity is an important factor in influencing the dissipation of the temperature inversion and the destruction of the CAP structure.