Widespread and persistent summer multi-day episodes of dense wildfire smoke affected western Canada in 2017 and 2018. These events often occurred under otherwise clear-sky, anticyclonic weather conditions and can have significant impacts on surface temperatures, air quality, and surface radiation and energy budgets. Based on upward-pointing lidar observations, vertical temperature soundings and numerical mesoscale modelling for a mountain in south-western British Columbia, Canada, we propose a previously undocumented stability-related impact of wildfire smoke layers on mountain meteorology. This positive feedback (that maintains layer structure and extends the lifetime of layers) appears to suppress mountain “handover processes”. Smoke days are characterized by more stable vertical temperature profiles when compared to clear-sky conditions, and are marked by a lack of diurnal variability in boundary-layer structure in lidar backscatter imagery. We expect the processes described to have general application and propose more detailed aerosol modelling to investigate the physical details of the process.

中文翻译：

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由于持续的野火烟雾抑制山地对流边界层中的“切换”过程

2017 年和 2018 年，加拿大西部发生了广泛而持续的多日浓密野火烟雾事件。这些事件通常发生在晴朗的反气旋天气条件下，可能对地表温度、空气质量以及地表辐射和能量产生重大影响预算。基于对加拿大不列颠哥伦比亚省西南部一座山的向上指向的激光雷达观测、垂直温度探测和数值中尺度建模，我们提出了野火烟雾层对山地气象的先前未记录的稳定性相关影响。这种正反馈（保持层结构并延长层的寿命）似乎抑制了山地“切换过程”。与晴空条件相比，烟雾天的特点是垂直温度分布更稳定，并且以激光雷达反向散射图像中边界层结构缺乏昼夜变化为特征。我们希望所描述的过程具有普遍应用，并提出更详细的气溶胶建模来研究过程的物理细节。