Abstract. In this study, we investigate the sensitivity of the glacial Alpine hydro-climate to northern hemispheric and local ice-sheet changes. Bridging the scale gap by using a chain of global and regional climate models, we perform sensitivity simulations of up to 2 km horizontal resolution over the Alps for the Last Glacial Maximum (LGM) and the Marine Isotope Stage 4 (MIS4). In winter, we find wetter conditions in the southern part of the Alps during LGM compared to present day, to which dynamical processes, i.e., changes in the wind speed and direction, substantially contribute. During summer, we find the expected drier conditions in most of the Alpine region during LGM, as thermodynamics suggests drier conditions under lower temperatures. The MIS4 climate shows enhanced winter precipitation compared to the LGM, which is explain by its warmer climate compared to the LGM – thus, again explained by thermodynamics. The sensitivity simulations of the northern hemispheric ice-sheet changes show that an increase of the ice-sheet thickness leads to a significant intensification of glacial Alpine hydro-climate conditions, which is mainly explained by dynamical processes. Changing only the Fennoscandian ice sheet is less influential on the Alpine precipitation, whereas modifications in the local Alpine ice-sheet topography significantly alter the Alpine precipitation, in particular we find a reduction of summer precipitation at the southern face of the Alps when lowering the Alpine ice sheet. The findings demonstrate that the northern hemispheric and local ice-sheet topography play an important role in regulating the Alpine hydro-climate and thus permits a better understanding of the precipitation patterns in the complex Alpine terrain at glacial times.

中文翻译：

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冰盖地形在冰川时期高山水文气候中的作用

摘要。在这项研究中，我们调查了冰川高山水文气候对北半球和当地冰盖变化的敏感性。通过使用一系列全球和区域气候模型来弥合尺度差距，我们在阿尔卑斯山上为末次盛冰期 (LGM) 和海洋同位素第 4 阶段 (MIS4) 执行高达 2 公里水平分辨率的灵敏度模拟。在冬季，我们发现 LGM 期间阿尔卑斯山南部的条件比现在更潮湿，动力过程，即风速和风向的变化，对此有很大贡献。在夏季，我们发现 LGM 期间大部分阿尔卑斯地区的预期干燥条件，因为热力学表明较低温度下的条件更干燥。与 LGM 相比，MIS4 气候显示冬季降水增强，这可以通过与 LGM 相比更温暖的气候来解释——因此，再次通过热力学来解释。北半球冰盖变化的敏感性模拟表明，冰盖厚度的增加导致冰川高山水文气候条件显着加剧，这主要由动力过程解释。仅改变 Fennoscandian 冰盖对高山降水的影响较小，而当地高山冰盖地形的改变显着改变了高山降水，特别是我们发现当降低高山时，阿尔卑斯南面夏季降水减少冰盖。