Experimental observation of transient &amp;lt;i&amp;gt;δ&amp;lt;/i&amp;gt;&amp;lt;sup&amp;gt;18&amp;lt;/sup&amp;gt;O interaction between snow and advective airflow under various temperature gradient conditions

Ebner, Pirmin Philipp; Steen-Larsen, Hans Christian; Stenni, Barbara; Schneebeli, Martin; Steinfeld, Aldo

doi:10.5194/tc-11-1733-2017

Cited by 32 publications

(27 citation statements)

References 61 publications

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“…However, our observations and modelling results appear to disagree with this approach, mainly due to the fact that the fractionation coefficients are only able to describe thermodynamic equilibrium conditions, which were not met in our case study. These in situ field results validate previous laboratory studies from Sokratov and Golubev (2009) and Ebner et al (2017), which also showed that thermodynamic equilibrium conditions were not able to describe the exchanges between snow and vapour.…”

Section: Discussionsupporting

confidence: 82%

“…Isotope exchanges during snow metamorphism and diffusion within the porous matrix of the subsurface snowpack additionally affect snow isotopic composition (Langway, 1970;Johnsen, 1977;Whillans and Grootes, 1985;Calonne et al, 2015;Ebner et al, 2017) and the diffusion length depends on the firn ventilation, the snow density, porosity and tortuosity and the exchange rate between the atmospheric water vapour and the surface snow (Johnsen et al, 2000;Gkinis et al, 2014). This large variety of processes hampers isotopic signal interpretation.…”

Section: Atmospheric Boundary Layermentioning

confidence: 99%

“…A large number of snow pits from Vostok station are presented here as well, which were previously described in Ekaykin et al (2002 and Ekaykin and Lipenkov (2009). We combine the results from six snow pits with depths varying from 2.5 to 12 m and a minimum resolution of 5 cm.…”

Section: Snow Pits Samplingmentioning

confidence: 99%

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Archival processes of the water stable isotope signal in East Antarctic ice cores

et al. 2018

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Abstract. The oldest ice core records are obtained from the East Antarctic Plateau. Water isotopes are key proxies to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in trajectory-based Rayleigh distillation and isotope-enabled climate models. However, a quantitative understanding of processes potentially altering snow isotopic composition after deposition is still missing. In low-accumulation sites, such as those found in East Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretability of an ice core's isotopic composition. By combining observations of isotopic composition in vapour, precipitation, surface snow and buried snow from Dome C, a deep ice core site on the East Antarctic Plateau, we found indications of a seasonal impact of metamorphism on the surface snow isotopic signal when compared to the initial precipitation. Particularly in summer, exchanges of water molecules between vapour and snow are driven by the diurnal sublimation–condensation cycles. Overall, we observe in between precipitation events modification of the surface snow isotopic composition. Using high-resolution water isotopic composition profiles from snow pits at five Antarctic sites with different accumulation rates, we identified common patterns which cannot be attributed to the seasonal variability of precipitation. These differences in the precipitation, surface snow and buried snow isotopic composition provide evidence of post-deposition processes affecting ice core records in low-accumulation areas.

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Section: Discussionsupporting

confidence: 82%

Section: Atmospheric Boundary Layermentioning

confidence: 99%

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Archival processes of the water stable isotope signal in East Antarctic ice cores

et al. 2018

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“…Isotopes have recently been implemented in the complex snowpack model CROCUS (Touzeau et al, 2018). The authors propose, similar to Ebner et al (2017), that a snow grain has an inner and outer isotopic composition, which is similar upon snowfall, but changes independently as the snow grain undergoes postdepositional processes. We propose that throughout a single day, the outer snow grain undergoes substantial changes in both volume and isotopic composition, whereas the inner snow grain isotopic composition stays constant.…”

Section: 1029/2018jd029619mentioning

confidence: 88%

Evidence of Isotopic Fractionation During Vapor Exchange Between the Atmosphere and the Snow Surface in Greenland

et al. 2019

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Several recent studies from both Greenland and Antarctica have reported significant changes in the water isotopic composition of near‐surface snow between precipitation events. These changes have been linked to isotopic exchange with atmospheric water vapor and sublimation‐induced fractionation, but the processes are poorly constrained by observations. Understanding and quantifying these processes are crucial to both the interpretation of ice core climate proxies and the formulation of isotope‐enabled general circulation models. Here, we present continuous measurements of the water isotopic composition in surface snow and atmospheric vapor together with near‐surface atmospheric turbulence and snow‐air latent and sensible heat fluxes, obtained at the East Greenland Ice‐Core Project drilling site in summer 2016. For two 4‐day‐long time periods, significant diurnal variations in atmospheric water isotopologues are observed. A model is developed to explore the impact of this variability on the surface snow isotopic composition. Our model suggests that the snow isotopic composition in the upper subcentimeter of the snow exhibits a diurnal variation with amplitudes in δ 18 O and δD of ~2.5‰ and ~13‰, respectively. As comparison, such changes correspond to 10–20% of the magnitude of seasonal changes in interior Greenland snow pack isotopes and of the change across a glacial‐interglacial transition. Importantly, our observation and model results suggest, that sublimation‐induced fractionation needs to be included in simulations of exchanges between the vapor and the snow surface on diurnal timescales during summer cloud‐free conditions in northeast Greenland.

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“…Recent studies have shown, however, that the in-E. Schlosser et al: Influence of the synoptic regime on stable water isotopes in precipitation at Dome C teraction between the uppermost layers of the snowpack and the overlying atmosphere between precipitation events also plays an important role. This was found in both Greenland Bonne et al, 2014) and Antarctica (Casado et al, 2016a, b;Ritter et al, 2016;Touzeau et al, 2016) as well as in laboratory experiments (Ebner et al, 2017).…”

Section: Ice Cores In Paleoclimatologymentioning

confidence: 94%

The influence of the synoptic regime on stable water isotopes in precipitation at Dome C, East Antarctica

Schlosser¹,

Dittmann²,

Stenni³

et al. 2017

The Cryosphere

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Abstract. The correct derivation of paleotemperatures from ice cores requires exact knowledge of all processes involved before and after the deposition of snow and the subsequent formation of ice. At the Antarctic deep ice core drilling site Dome C, a unique data set of daily precipitation amount, type, and stable water isotope ratios is available that enables us to study in detail atmospheric processes that influence the stable water isotope ratio of precipitation. Meteorological data from both automatic weather station and a mesoscale atmospheric model were used to investigate how different atmospheric flow patterns determine the precipitation parameters. A classification of synoptic situations that cause precipitation at Dome C was established and, together with back-trajectory calculations, was utilized to estimate moisture source areas. With the resulting source area conditions (wind speed, sea surface temperature, and relative humidity) as input, the precipitation stable isotopic composition was modeled using the so-called Mixed Cloud Isotope Model (MCIM). The model generally underestimates the depletion of 18 O in precipitation, which was not improved by using condensation temperature rather than inversion temperature. Contrary to the assumption widely used in ice core studies, a more northern moisture source does not necessarily mean stronger isotopic fractionation. This is due to the fact that snowfall events at Dome C are often associated with warm air advection due to amplification of planetary waves, which considerably increases the site temperature and thus reduces the temperature difference between source area and deposition site. In addition, no correlation was found between relative humidity at the moisture source and the deuterium excess in precipitation. The significant difference in the isotopic signal of hoarfrost and diamond dust was shown to disappear after removal of seasonality. This study confirms the results of an earlier study carried out at Dome Fuji with a shorter data set using the same methods.

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Experimental observation of transient <i>δ</i><sup>18</sup>O interaction between snow and advective airflow under various temperature gradient conditions

Cited by 32 publications

References 61 publications

Archival processes of the water stable isotope signal in East Antarctic ice cores

Archival processes of the water stable isotope signal in East Antarctic ice cores

Evidence of Isotopic Fractionation During Vapor Exchange Between the Atmosphere and the Snow Surface in Greenland

The influence of the synoptic regime on stable water isotopes in precipitation at Dome C, East Antarctica

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