Calving is a crucial process for the mass loss of outlet glaciers in Greenland, while at the same time the calving contributes to large uncertainties in current glacier flow models and projections, particularly due to a lack of observations. Here we investigate the frequency, volume and style of calving events by using high-resolution terrestrial radar interferometer data from six field campaigns, continuous daily and hourly time-lapse images over six years and 10-second time-lapse images recorded during two field campaigns. The results demonstrate that the calving front of Eqip Sermia, a fast flowing, highly crevassed outlet glacier in West Greenland, follows a clear seasonal cycle showing a distinct pattern in areas with subglacial discharge plumes, shallow bed topography and during the presence and retreat of proglacial ice mélange. Calving event volume, frequency and style vary strongly over time depending on the state in the seasonal cycle. Strong spatial differences between three distinctive front sectors with differing bed topography, water depth and calving front slope were observed. A distinct increase in calving activity occurs in the early melt season simultaneously when ice mélange disappears and meltwater plumes become visible at the fjord surface adjacent to the ice front. While reduced retreat of the front is observed in shallow areas, accelerated retreat occurred at locations with subglacial meltwater plumes. With the emergence of these plumes at the beginning of the melt season, larger full thickness calving events occur likely due to undercutting of the calving front. Later in the melt season the calving activity at subglacial meltwater plumes is similar to the neighboring areas, suggesting the presence of plumes to become less important for calving. The results highlight the significance of subglacial discharge and bed topography on the front geometry, the temporal variability of the calving process and the variability of calving styles.

中文翻译：

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冰川产犊样式和样式的周期性季节性周期的驱动因素

产犊是格陵兰出口冰川大量流失的关键过程，同时，产犊导致当前冰川流动模型和预测的巨大不确定性，特别是由于缺乏观测。在这里，我们通过使用来自六个野战的高分辨率地面雷达干涉仪数据，六年中连续的每日和每小时时移图像以及六年中两次运动记录的10秒时移图像，来研究产犊事件的频率，数量和样式。结果表明，西格陵兰岛Eqip Sermia（一条快速流动，高度裂缝的出口冰川）的front陷锋线遵循明显的季节性周期，显示出冰川下流出羽状流，浅层地形以及冰期存在和后退期间的明显模式。冰混杂。产犊事件的数量，频率和样式随时间变化很大，具体取决于季节周期中的状态。观察到三个具有不同床形，水深和产犊前倾角的独特的前扇形之间的强烈空间差异。在冰融化的消失和融水羽流在邻近冰锋的峡湾表面可见的同时，在早期的融化季节，产犊活动也明显增加。尽管在浅水区观察到前锋的退缩减少，但在冰川下融水羽流的位置加速退缩。随着这些羽状物在融化季节开始时的出现，较大的全厚度产犊事件很可能是由于产犊前缘的欠挖而发生的。在融化季节后期，冰川下融水羽流的产犊活动与附近地区相似，这表明羽流的存在对产犊的重要性降低。结果突出了冰川下泄物和床的地形对前部几何学的重要性，产犊过程的时间变异性和产犊方式的变异性。