Numerical experiments on isotopic diffusion in polar snow and firn using a multi-layer energy balance model

Touzeau, Alexandra; Landais, Amaëlle; Morin, Samuel; Arnaud, Laurent; Picard, Ghislain

doi:10.5194/gmd-2017-217

Cited by 2 publications

(1 citation statement)

References 63 publications

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“…Specifically, vapor‐snow exchange processes occur continuously at the surface through turbulent humidity fluxes (Wahl et al., 2021 ) which are defined by local climate and below the surface during snow metamorphism. The latter is influenced by local climate through temperature shifts that induce temperature gradients in the snow and trigger interstitial vapor diffusion and associated snow recrystallization (Casado et al., 2021 ; Ebner et al., 2017 ; Touzeau et al., 2017 ). Thus, post‐depositional processes represent a potential mechanism behind the observed strong correlation between local temperature and the isotopic composition of snow and ice on various timescales other than Rayleigh distillation.…”

Section: Introductionmentioning

confidence: 99%

Atmosphere‐Snow Exchange Explains Surface Snow Isotope Variability

Wahl

Steen‐Larsen

Zuhr

et al. 2022

Geophysical Research Letters

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Ice cores allow paleo-climate reconstructions through climate proxies such as stable water isotope records. An accurate understanding of the transfer function between the climatic conditions and the ice core stable water isotope signal is thus crucial and important for integrating stable water isotope records in climate models. The rationale behind using ice core isotope records as climate proxies is the temperature dependency of the isotopic composition of precipitation that can be described by a Rayleigh distillation process. However, the assumption that the ice core climate signal is governed by the precipitation isotope signal alone has previously been challenged (

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Section: Introductionmentioning

confidence: 99%

Atmosphere‐Snow Exchange Explains Surface Snow Isotope Variability

Wahl

Steen‐Larsen

Zuhr

et al. 2022

Geophysical Research Letters

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Water stable isotope spatio-temporal variability in Antarctica in 1960–2013: observations and simulations from the ECHAM5-wiso atmospheric general circulation model

et al. 2018

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Polar ice core water isotope records are commonly used to infer past changes in Antarctic temperature, motivating an improved understanding and quantification of the temporal relationship between δ 18 O and temperature. This can be achieved using simulations performed by atmospheric general circulation models equipped with water stable isotopes. Here, we evaluate the skills of the highresolution water-isotope-enabled atmospheric general circulation model ECHAM5-wiso (the European Centre Hamburg Model) nudged to European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis using simulations covering the period 1960-2013 over the Antarctic continent.We compare model outputs with field data, first with a focus on regional climate variables and second on water stable isotopes, using our updated dataset of water stable isotope measurements from precipitation, snow, and firn-ice core samples. ECHAM5-wiso simulates a large increase in temperature from 1978 to 1979, possibly caused by a discontinuity in the European Reanalyses (ERA) linked to the assimilation of remote sensing data starting in 1979.Although some model-data mismatches are observed, the (precipitation minus evaporation) outputs are found to be realistic products for surface mass balance. A warm model bias over central East Antarctica and a cold model bias over coastal regions explain first-order δ 18 O model biases by toostrong isotopic depletion on coastal areas and underestimated depletion inland. At the second order, despite these biases, ECHAM5-wiso correctly captures the observed spatial patterns of deuterium excess. The results of model-data comparisons for the inter-annual δ 18 O standard deviation dif-fer when using precipitation or ice core data. Further studies should explore the importance of deposition and postdeposition processes affecting ice core signals and not resolved in the model.These results build trust in the use of ECHAM5-wiso outputs to investigate the spatial, seasonal, and inter-annual δ 18 O-temperature relationships. We thus make the first Antarctica-wide synthesis of prior results. First, we show that local spatial or seasonal slopes are not a correct surrogate for inter-annual temporal slopes, leading to the conclusion that the same isotope-temperature slope cannot be applied for the climatic interpretation of Antarctic ice core for all timescales. Finally, we explore the phasing between the seasonal cycles of deuterium excess and δ 18 O as a source of information on changes in moisture sources affecting the δ 18 O-temperature relationship. The few available records and ECHAM5-wiso show different phase relationships in coastal, intermediate, and central regions.This work evaluates the use of the ECHAM5-wiso model as a tool for the investigation of water stable isotopes in Antarctic precipitation and calls for extended studies to improve our understanding of such proxies.

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Numerical experiments on isotopic diffusion in polar snow and firn using a multi-layer energy balance model

Cited by 2 publications

References 63 publications

Atmosphere‐Snow Exchange Explains Surface Snow Isotope Variability

Atmosphere‐Snow Exchange Explains Surface Snow Isotope Variability

Water stable isotope spatio-temporal variability in Antarctica in 1960–2013: observations and simulations from the ECHAM5-wiso atmospheric general circulation model

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