Publikationsdatum:
2024-04-19
Beschreibung:
The stable water isotopic composition in firn and ice cores provides valuable information on past climatic conditions. Because of uneven accumulation and post‐depositional modifications on local spatial scales up to hundreds of meters, time series derived from adjacent cores differ significantly and do not directly reflect the temporal evolution of the precipitated snow isotopic signal. Hence, a characterization of how the isotopic profile in the snow develops is needed to reliably interpret the isotopic variability in firn and ice cores. By combining digital elevation models of the snow surface and repeated high‐resolution snow sampling for stable water isotope measurements of a transect at the East Greenland Ice‐core Project campsite on the Greenland Ice Sheet, we are able to visualize the buildup and post‐depositional changes of the upper snowpack across one summer season. To this end, 30 cm deep snow profiles were sampled on six dates at 20 adjacent locations along a 40 m transect. Near‐daily photogrammetry provided snow height information for the same transect. Our data shows that erosion and redeposition of the original snowfall lead to a complex stratification in the δ〈sup〉18〈/sup〉O signature. Post‐depositional processes through vapor‐snow exchange affect the near surface snow with d‐excess showing a decrease in surface and near‐surface layers. Our data suggests that the interplay of stratigraphic noise, accumulation intermittency, and local post‐depositional processes form the proxy signal in the upper snowpack.
Beschreibung:
Plain Language Summary:
We study the process of the formation of the stable water isotope signal in surface snow on the Greenland Ice Sheet to better understand temperature information which is stored as a climate proxy in snow and ice. Our data consist of high‐resolution surface topography information illustrating the timing and location of snowfall, erosion, and redeposition along a transect of 40 m, as well as stable water isotope records of the upper 30 cm of the snowpack sampled biweekly on 20 positions at the same 40 m long transect. The data cover a 2‐month period during the summer of 2019. We find that the isotopic composition shows spatial variability of layers with low and high values, presumably winter and summer layers. We further observe that prevailing surface structures, such as dunes, influence the snow deposition and contribute to the found variable structure of the climatic information. Eventually, snow accumulation alone cannot explain all of the observed patterns in the isotopic data which is likely related to exchange processes between the snow and the atmosphere which modify the signal in the snow column after deposition.
Beschreibung:
Key Points:
Combining digital elevation models and repeated snow sampling reveals the heterogeneous buildup of δ〈sup〉18〈/sup〉O signal in the snow column.
Surface structures (stratigraphic noise) substantially contribute to internal heterogeneity in δ〈sup〉18〈/sup〉O signature in the upper snowpack.
Proxy signals are formed in the surface layer by local processes, advected downwards with limited post‐depositional influences below 10 cm.
Beschreibung:
Horizon 2020 Framework Programme
http://dx.doi.org/10.13039/100010661
Beschreibung:
A. P. Møller Foundation, University of Copenhagen
Beschreibung:
US National Science Foundation, Office of Polar Programs
Beschreibung:
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
Beschreibung:
National Institute of Polar Research and Arctic Challenge for Sustainability
Beschreibung:
University of Bergen
Beschreibung:
Trond Mohn Foundation
Beschreibung:
Swiss National Science Foundation
Beschreibung:
French Polar Institute Paul‐Emile Victor, Institute for Geosciences and Environmental Research
Beschreibung:
University of Manitoba
Beschreibung:
Chinese Academy of Sciences
Beschreibung:
Beijing Normal University
Beschreibung:
https://doi.org/10.1594/PANGAEA.954944
Beschreibung:
https://doi.org/10.1594/PANGAEA.954945
Beschreibung:
https://doi.org/10.1594/PANGAEA.951583
Beschreibung:
https://doi.org/10.1594/PANGAEA.925618
Beschreibung:
https://doi.org/10.1594/PANGAEA.928827
Beschreibung:
https://www.agisoft.com/downloads/installer/
Schlagwort(e):
ddc:551
;
proxy
;
Greenland
;
isotopes
;
structure‐from‐motion
;
snow accumulation
;
ice core
Sprache:
Englisch
Materialart:
doc-type:article
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