Abstract Supraglacial debris complicates the melting state of debris-covered glaciers, and whether debris increases or decreases the rate of glacier melt is ambiguous according to different observations. In this paper, we aim to determine the potential factors that influence changes in thickness of debris-covered glaciers. First, we present the thickness changes of a large debris-covered glacier in the Tienshan Mountain using high-resolution Digital Elevation Model (DEM) data from three periods in 2000, 2009 and 2013. It is shown that the thickness changes differ greatly over the debris-covered portions of the glacier. These debris-covered regions can be divided into three parts along the glacier axis according to the rate of thickness change. Specifically, these parts include the zone of minimal change, the zone of heavy thinning, and the zone of slight thinning. Detailed information on the closely related factors, including the debris thickness, which was measured across the whole glacier during our field work, and the presence of ice cliffs and supraglacial lakes detected on high-resolution satellite images, are combined to determine the reasons for the differences in melting state among the three zones. The results show that the thickness changes of the debris-covered glacier are jointly influenced by debris thickness and the presence of ice cliffs and supraglacial lakes; moreover, the dominant factor differs among the different zones. The critical debris thickness, which mostly appears in the minimal change zone and accelerates glacier melting, as confirmed through field observations, is not associated with glacier thinning because its location is close to the accumulation zone. The regions where the rates of thinning are greatest coincide with the regions where the ice cliffs are densest. Where the debris is thicker than 1 m on average, the glacier is still thinning slightly due to the presence of ice cliffs and lakes. It is proven that the quantity and area of the ice cliffs and supraglacial lakes is the key to understanding the melting rate of debris covered glacier.

中文翻译：

---

天山碎屑冰川厚度变化及驱动因素分析

摘要 冰上碎屑使被碎屑覆盖的冰川的融化状态复杂化，根据不同的观察，碎屑是增加还是减少冰川融化的速度是不明确的。在本文中，我们旨在确定影响碎片覆盖冰川厚度变化的潜在因素。首先，我们利用 2000、2009 和 2013 年三个时期的高分辨率数字高程模型 (DEM) 数据展示了天山大型碎屑覆盖冰川的厚度变化。冰川碎片覆盖的部分。这些碎片覆盖的区域可以根据厚度变化的速度沿冰川轴分为三个部分。具体来说，这些部分包括最小变化区、严重减薄区、和轻微变薄的区域。结合密切相关因素的详细信息，包括我们在野外工作期间在整个冰川上测量的碎片厚度，以及高分辨率卫星图像上检测到的冰崖和冰上湖泊的存在，以确定导致三个区域的熔化状态不同。结果表明，碎屑覆盖冰川的厚度变化受碎屑厚度和冰崖、冰上湖泊的存在共同影响；此外，不同区域的主导因素不同。通过野外观测证实，临界碎片厚度，主要出现在最小变化区并加速冰川融化，与冰川变薄无关，因为它的位置靠近堆积区。变薄率最大的区域与冰崖最密集的区域重合。在碎片平均厚度超过 1 m 的地方，由于冰崖和湖泊的存在，冰川仍在略微变薄。事实证明，冰崖和冰上湖泊的数量和面积是了解碎屑覆盖冰川融化速度的关键。