On the relationship between <i>δ</i>O<sub>2</sub>∕N<sub>2</sub> variability and ice sheet surface conditions in Antarctica - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Cryosphere Année : 2024

On the relationship between δO2∕N2 variability and ice sheet surface conditions in Antarctica

Marie Dumont
Quentin Libois
Robert Mulvaney

Résumé

While the processes controlling pore closure are broadly understood, the physical mechanisms driving the associated elemental fractionation remains ambiguous. Previous studies have shown that the pore closure process leads to a depletion in small-sized molecules (e.g. H 2 , O 2 , Ar, Ne, He) in ice core bubbles relative to larger-sized molecules like N 2 . This size-dependent fractionation, identified using ice core δ(O 2 /N 2 ) records, exhibits a clear anti-correlation with local summer solstice insolation, making δ(O 2 /N 2 ) a valuable ice core dating tool. Mechanisms controlling this relationship are attributed to the physical properties of deep firn. In this study, we compile δ(O 2 /N 2 ) records from 15 polar ice cores and show a new additional link between δ(O 2 /N 2 ) and local surface temperature and/or accumulation rate. Using the Crocus snowpack model, we perform sensitivity tests to identify the response of near-surface snow properties to changes in insolation intensity, accumulation rate, and air temperature. These tests support a mechanism linked to firn grain size, such that the larger the grain size for a given density, the stronger the pore closure fractionation and, hence, the lower the δ(O 2 /N 2 ) values archived in the ice. Based on both snowpack model outputs and data compilation, our findings suggest that local accumulation rate and temperature should be considered when interpreting δ(O 2 /N 2 ) as a local insolation proxy.

Fichier principal
Vignette du fichier
tc-18-3741-2024.pdf (3.67 Mo) Télécharger le fichier
Origine Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-04679707 , version 1 (28-08-2024)

Identifiants

Citer

Romilly Harris Stuart, Amaelle Landais, Laurent Arnaud, Christo Buizert, Emilie Capron, et al.. On the relationship between δO2∕N2 variability and ice sheet surface conditions in Antarctica. The Cryosphere, 2024, 18 (8), pp.3741 - 3763. ⟨10.5194/tc-18-3741-2024⟩. ⟨hal-04679707⟩
0 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Mastodon Facebook X LinkedIn More