دورية أكاديمية
Controls on the movement and composition of firn air at the West Antarctic Ice Sheet Divide
| العنوان: | Controls on the movement and composition of firn air at the West Antarctic Ice Sheet Divide |
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| المؤلفون: | M. O. Battle, J. P. Severinghaus, E. D. Sofen, D. Plotkin, A. J. Orsi, M. Aydin, S. A. Montzka, T. Sowers, P. P. Tans |
| المصدر: | Atmospheric Chemistry and Physics, Vol 11, Iss 21, Pp 11007-11021 (2011) |
| بيانات النشر: | Copernicus Publications, 2011. |
| سنة النشر: | 2011 |
| المجموعة: | LCC:Physics LCC:Chemistry |
| مصطلحات موضوعية: | Physics, QC1-999, Chemistry, QD1-999 |
| الوصف: | We sampled interstitial air from the perennial snowpack (firn) at a site near the West Antarctic Ice Sheet Divide (WAIS-D) and analyzed the air samples for a wide variety of gas species and their isotopes. We find limited convective influence (1.4–5.2 m, depending on detection method) in the shallow firn, gravitational enrichment of heavy species throughout the diffusive column in general agreement with theoretical expectations, a ~10 m thick lock-in zone beginning at ~67 m, and a total firn thickness consistent with predictions of Kaspers et al. (2004). Our modeling work shows that the air has an age spread (spectral width) of 4.8 yr for CO2 at the firn-ice transition. We also find that advection of firn air due to the 22 cm yr−1 ice-equivalent accumulation rate has a minor impact on firn air composition, causing changes that are comparable to other modeling uncertainties and intrinsic sample variability. Furthermore, estimates of Δage (the gas age/ice age difference) at WAIS-D appear to be largely unaffected by bubble closure above the lock-in zone. Within the lock-in zone, small gas species and their isotopes show evidence of size-dependent fractionation due to permeation through the ice lattice with a size threshold of 0.36 nm, as at other sites. We also see an unequivocal and unprecedented signal of oxygen isotope fractionation within the lock-in zone, which we interpret as the mass-dependent expression of a size-dependent fractionation process. |
| نوع الوثيقة: | article |
| وصف الملف: | electronic resource |
| اللغة: | English |
| تدمد: | 1680-7316 1680-7324 24999741 |
| Relation: | http://www.atmos-chem-phys.net/11/11007/2011/acp-11-11007-2011.pdf; https://doaj.org/toc/1680-7316; https://doaj.org/toc/1680-7324 |
| DOI: | 10.5194/acp-11-11007-2011 |
| URL الوصول: | https://doaj.org/article/469efb24999741e0bae2f69fedc7c95c |
| رقم الأكسشن: | edsdoj.469efb24999741e0bae2f69fedc7c95c |
| قاعدة البيانات: | Directory of Open Access Journals |
Full Text Finder | تدمد: | 16807316 16807324 24999741 |
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| DOI: | 10.5194/acp-11-11007-2011 |