Preprints
https://doi.org/10.5194/tc-2021-36
https://doi.org/10.5194/tc-2021-36

  10 Feb 2021

10 Feb 2021

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

Local scale depositional processes of surface snow on the Greenland ice sheet

Alexandra M. Zuhr1,2, Thomas Münch1, Hans Christian Steen-Larsen3, Maria Hörhold4, and Thomas Laepple1,5 Alexandra M. Zuhr et al.
  • 1Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung, Research Unit Potsdam, Telegrafenberg A45, 14473 Potsdam, Germany
  • 2University of Potsdam, Institute of Geosciences, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany
  • 3Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway
  • 4Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung, Research Unit Bremerhaven, 27568 Bremerhaven, Germany
  • 5University of Bremen, MARUM - Center for Marine Environmental Sciences and Faculty of Geosciences, 28334 Bremen, Germany

Abstract. Ice cores from polar ice sheets and glaciers are an important climate archive. Snow layers, consecutively deposited and buried, contain climatic information of the time of their formation. However, particularly low-accumulation areas are characterised by temporally intermittent precipitation, which can be further re-distributed after initial deposition. Therefore, the local conditions of accumulation at an ice core site influence the quantity and quality of the recorded climate signal in proxy records. Local surface features at different spatial scales further affect the signal imprint. This study therefore aims to characterise the local accumulation patterns and the evolution of the snow height to describe the contribution of snow (re-)deposition to noise in climate records from ice cores. By using a photogrammetry Structure-from-Motion approach, we generated near-daily elevation models of the snow surface for a 195 m2 area in the vicinity of the deep drilling site of the East Greenland Ice Core Project in northeast Greenland. Based on the snow height information we derived snow height changes on a day-to-day basis throughout our observation period from May to August 2018. Specifically, the average snow height increased by ~11 cm. The spatial and temporal data set allowed an investigation of snow deposition versus depositional modifications. We observed irregular snow deposition, erosion, and the re-distribution of snow, which caused uneven snow accumulation patterns, a removal of more than 60 % of the deposited snow, and a negative relationship between the initial snow height and the amount of accumulated snow. Furthermore, the surface roughness decreased from 4 to 2 cm throughout the spring and summer season at our study site. Finally, our study further shows that our method has several advantages over previous approaches, making it possible to demonstrate the importance of accumulation intermittency, and the potential influences of depositional processes on proxy signals in snow and ice.

Alexandra M. Zuhr et al.

Status: open (until 07 Apr 2021)

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Alexandra M. Zuhr et al.

Data sets

Snow height data generated with a Structure-from-Motion photogrammetry approach at the EGRIP camp site in 2018 Zuhr, A., Münch, T., Steen-Larsen, H. C., Hörhold, M., and Laepple, T. https://doi.org/10.1594/PANGAEA.923418

Snow surface accumulation measured using SSA stake measurents, EastGRIP camp Greenland, May 2018 Steen-Larsen, H. C. https://doi.pangaea.de/10.1594/PANGAEA.921853

Snow surface accumulation measured using Bamboo stake measurents, EastGRIP camp Greenland, May 2016 Steen-Larsen, H. C. https://doi.pangaea.de/10.1594/PANGAEA.921855

Alexandra M. Zuhr et al.

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Short summary
Firn and ice cores are used to infer past temperatures. However, the imprint of the climatic signal in stable water isotopes is influenced by depositional modifications. We present and use a photogrammetry Structure-from-Motion approach. We find variability in the amount, the timing and the location of snowfall. Further depositional modifications of the surface are observed leading to mixing of snow from different snowfall events and spatial locations and thus, create noise in the proxy record.