Preprints
https://doi.org/10.5194/cp-2021-67
https://doi.org/10.5194/cp-2021-67

  21 Jun 2021

21 Jun 2021

Review status: this preprint is currently under review for the journal CP.

The Role of Ice-Sheet Topography in the Alpine Hydro-Climate at Glacial Times

Patricio Velasquez1,2, Martina Messmer1,2, and Christoph C. Raible1,2 Patricio Velasquez et al.
  • 1Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland
  • 2Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland

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.

Patricio Velasquez et al.

Status: open (until 16 Aug 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-67', Maria Fernanda Sanchez Goñi, 04 Jul 2021 reply

Patricio Velasquez et al.

Patricio Velasquez et al.

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Short summary
We investigate the sensitivity of the glacial Alpine hydro-climate to northern hemispheric and local ice-sheet changes. We perform sensitivity simulations of up to 2 km horizontal resolution over the Alps for the glacial periods. 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 Alpine precipitation patterns at glacial times.