Studying the daily evolution of turbulent fluxes modulated by snowfall over the Tibetan Plateau (TP) is of great importance to understand the features of the change in the TP heat source/sink and its contribution to Asian atmospheric circulation and weather processes. However, the lack of data over the TP restricts the detailed studies. Based on observations from four sites of the Third TP Atmospheric Scientific Experiment, the process of surface energy balance impacted by snow is investigated. The results show that the surface albedo largely increases on the first day of snow and then slowly decreases. Correspondingly, the sensible heat (H) flux sharply decreases after snow and then gradually recovers to the original level during the following approximately 10 days. The latent heat (LE) flux becomes more active and stronger after snowfall and persists for a longer period than H, since the soil moisture may still contribute to a high LE after snowmelt. As the synergistic result of H and LE modulated by snow, the surface turbulent heating (i.e., the sum H and LE) of the TP decreases at the early period of snow events and then even enhances to a higher level after the snowmelt than before snow. Comparison analyses reveal that the impact of snow on the H and LE over the TP is much stronger than over similar latitude low-altitude regions in North America and Europe, which may be partly attributed to the larger and more drastic change of the surface net solar radiation associated with snow processes in the TP. The ERA5 and CFS reanalysis data sets fail to reproduce the modulation of snow on the heat fluxes, which suggests that the physical schemes of the models should be further improved based on the observational analyses over TP. This study may help further understand the detailed physical processes of modulation of snow events on Asian weather processes during winter and is also conducive to the improvement of surface parameterization schemes of models.

中文翻译：

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雪对青藏高原冬季地表加热日变化的调制：观测分析

研究青藏高原（TP）降雪调制的湍流通量的日常演变对于理解青藏高原热源/汇变化的特征及其对亚洲大气环流和天气过程的贡献具有重要意义。然而，TP 数据的缺乏限制了详细的研究。基于第三次TP大气科学实验四个站点的观测，研究了雪对地表能量平衡的影响过程。结果表明，地表反照率在下雪的第一天大幅增加，然后缓慢减少。相应地，雪后显热（H）通量急剧下降，然后在接下来的大约 10 天内逐渐恢复到原始水平。降雪后潜热 (LE) 通量变得更加活跃和更强，并且持续时间比 H 更长，因为在融雪后土壤水分仍可能导致高 LE。由于 H 和 LE 被雪调制的协同结果，TP 的表面湍流加热（即 H 和 LE 的总和）在雪事件的早期减少，然后在融雪后比雪前增强到更高的水平. 对比分析表明，雪对青藏高原H和LE的影响远强于北美和欧洲类似纬度的低海拔地区，部分原因可能是地表净太阳变化更大更剧烈。与青藏高原降雪过程相关的辐射。ERA5 和 CFS 再分析数据集未能重现雪对热通量的调制，这表明在TP的观测分析的基础上，模型的物理方案应该进一步改进。该研究有助于进一步了解冬季降雪事件对亚洲天气过程调制的详细物理过程，也有利于模型地表参数化方案的改进。