The land surface layer is an important interface between the ground and atmosphere, and cross-surface ground heat flux (G0) has a significant impact on land surface energy processes and associated cycles. Therefore, understanding dynamics in G0 is critical for predicting climate changes and developing adaptation strategies. However, the harsh environment and geographic barriers of the Tibetan Plateau have led to a significant lack of observations and soil samples, ultimately limiting the accuracy and application of G0 calculations. Here we investigated the changes in G0 at the BJ station, a typical seasonally frozen ground region of the Tibetan Plateau, through soil sampling and long-term in-situ observations. We used the calorimetric method to minimize reliance on model assumptions, aiming to achieve consistent and broadly applicable results. During the freezing-to-thawing and thawing-to-freezing stages, daytime G0 decreased while nighttime G0 increased. Conversely, daytime G0 increased while nighttime G0 decreased in the completely thawed and completely frozen stages. In moist conditions, more energy was directed toward soil moisture evaporation and vegetation transpiration, whereas in dry conditions, net radiation primarily increased soil temperature, enhancing G0. Our results revealed the dynamic changes in G0 across different environmental conditions and their impact on land-atmosphere interactions, and that climate warming and humidifying will diminish the regulatory capacity of G0. This study highlights the essential requirement for accurate G0 to predict future climate changes accurately, emphasizing its importance for researchers focusing on land-atmosphere feedback mechanisms and climate modeling.

中文翻译：

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加深对青藏高原腹地地热通量增温和加湿的理解


地表层是地面与大气之间的重要界面，跨地表地热通量 （G0） 对地表能量过程和相关循环有重大影响。因此，了解 G0 中的动力学对于预测气候变化和制定适应策略至关重要。然而，青藏高原恶劣的环境和地理障碍导致观测和土壤样本严重缺乏，最终限制了 G0 计算的准确性和应用。在这里，我们通过土壤采样和长期原位观测，研究了青藏高原典型的季节性冻土区 BJ 站 G0 的变化。我们使用量热法来最大限度地减少对模型假设的依赖，旨在获得一致且广泛适用的结果。在冻融和解冻到冰点阶段，白天 G0 降低，夜间 G0 增加。相反，在完全解冻和完全冻结阶段，白天 G0 增加，夜间 G0 降低。在潮湿条件下，更多的能量被用于土壤水分蒸发和植被蒸腾，而在干燥条件下，净辐射主要提高土壤温度，增强 G0。我们的结果揭示了 G0 在不同环境条件下的动态变化及其对陆地-大气相互作用的影响，气候变暖和加湿会削弱 G0 的调节能力。本研究强调了准确 G0 准确预测未来气候变化的基本要求，强调了其对专注于陆地-大气反馈机制和气候建模的研究人员的重要性。