The Tibetan Plateau (TP) has the largest permafrost area in the low- and mid-latitudes. With warmer ground temperatures and ice-rich terrain, the TP permafrost is potentially more vulnerable to climate warming. Abrupt thaw induced by rapid ground ice melt and thermokarst process has become more frequent in the TP, which will likely have a large impact on the regional water and carbon exchanges. This review presents recent researches on the drivers of abrupt thaw, with a focus on the hillslope thermokarst, and advances in remote sensing and process-based modeling of abrupt thaw process and the permafrost carbon feedback in the TP, with a comparison to the Arctic studies. Ground ice content and local topography are the two main factors controlling the rate and form of abrupt thaw; however, a lack of accurate estimates of ground ice content distribution and challenges in characterizing lateral heat transfer and groundwater flows greatly limit modeling capability in representing fine-scale thermokarst processes at a regional scale. High resolution satellite remote sensing has been widely used to identify various thermokarst landforms across the TP. However, studies using multi-source remote sensing to quantify the thermokarst-induced soil volume ice and mass loss are still lacking, particularly in the TP, which are important for characterizing the permafrost carbon feedback with abrupt thaw. Integration of spatial information derived from multi-source remote sensing with process-based models will allow better characterization of abrupt thaw processes, which generally occur at scales finer than model grid cells and are difficult to parameterize for coarse-resolution global and regional models. This synthesis can inform future research on better representing abrupt thaw process not only in the TP region but extending to other permafrost areas as well.

中文翻译：

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青藏高原急融及其对多年冻土碳排放的影响：遥感与建模视角


青藏高原 （TP） 拥有低纬度和中纬度地区最大的永久冻土区。随着地面温度升高和冰雪丰富的地形，青藏高原永久冻土可能更容易受到气候变暖的影响。在青藏高原，地面冰的快速融化和热岩溶过程引起的突然融化变得更加频繁，这可能会对区域水碳交换产生重大影响。本文综述了关于突变融化驱动因素的最新研究，重点是山坡热岩溶，以及高原地区突变融化过程和多年冻土碳反馈的遥感和基于过程的建模进展，并与北极研究进行了比较。地面冰含量和局部地形是控制突然融化速率和形式的两个主要因素;然而，缺乏对地面冰含量分布的准确估计以及描述横向传热和地下水流的挑战极大地限制了在区域范围内表示精细尺度热岩溶过程的建模能力。高分辨率卫星遥感已被广泛用于识别青藏高原的各种热喀斯特地貌。然而，仍然缺乏使用多源遥感来量化热岩溶引起的土壤体积冰和质量损失的研究，尤其是在青藏高原，这对于描述突然融化的永久冻土碳反馈非常重要。将多源遥感获得的空间信息与基于过程的模型相结合，可以更好地描述突然解冻过程，这些过程通常发生在比模型网格单元更精细的尺度上，并且很难为粗分辨率全球和区域模型参数化。 这种综合可以为未来的研究提供信息，不仅可以在 TP 区域更好地表示突然融化过程，还可以扩展到其他永久冻土区。