峨眉山低空边界层无人机探测与数值模拟研究

Investigation of the Low-Level Boundary Layer over Mount Emei Based on UAV Observations and Numerical Simulations

摘要:

边界层是大气中动量、热量和物质传输的重要区域，其气象要素变化对对流过程的理解至关重要。利用旋翼无人机探空数据，激光雷达和测风塔数据进行对比分析，并利用中尺度气象模式WRF进行模拟，验证模拟和观测结果的准确性。研究发现，森林覆盖增加地表粗糙度，降低近地风速，干扰垂直混合，形成明显的风速梯度。白天，太阳加热和植物蒸腾提高近地面相对湿度，边界层高度升至约900m，气温达18℃，相对湿度降至35%，反映活跃的垂直混合；夜间，辐射冷却和树冠遮蔽加速地表降温，形成逆温层，抑制湍流，相对湿度升至50%以上，边界层高度降至100~200m，形成稳定层。WRF模式模拟的温度、相对湿度和边界层高度与观测结果基本一致，表明高分辨率的数值模式在复杂地形区域对低空边界层气象要素模拟的准确性。研究结果为深入理解高原复杂地形条件下边界层特征及其对气候变化的响应提供了重要科学依据。

Abstract:

The boundary layer is a critical region in the atmosphere for the transport of momentum, heat, and matter, and its meteorological variations are essential for understanding convective processes. Using sounding data from rotary-wing unmanned aerial vehicles (UAVs), lidar measurements, and wind tower observations, a comparative analysis was conducted, and the mesoscale meteorological model WRF was employed to simulate and validate the accuracy of the observational and modeled results. The study found that increased forest cover enhances surface roughness, reduces near-surface wind speed, and disrupts vertical mixing, resulting in a clear wind speed gradient. During the daytime, solar heating and plant transpiration increase near-surface relative humidity, raising the boundary layer height to approximately 900m, with air temperatures reaching 18°C and relative humidity dropping to 35%, indicating vertical mixing. At night, radiative cooling and canopy shielding accelerate surface cooling, forming an inversion layer, suppressing turbulence, increasing relative humidity to over 50%, and lowering the boundary layer height to 100~200m, resulting in a stable layer. The WRF model’s simulations of temperature, relative humidity, and boundary layer height closely matched the observational results, demonstrating the accuracy of high-resolution numerical models in simulating low-level boundary layer meteorological elements in regions with complex terrain. These findings provide important scientific insights for understanding the characteristics of the boundary layer under plateau complex terrain conditions and its response to climate change.