Using noble gas measurements to derive air-sea process information and predict physical gas saturations

TitleUsing noble gas measurements to derive air-sea process information and predict physical gas saturations
Publication TypeJournal Article
Year of Publication2017
AuthorsHamme R.C, Emerson S.R, Severinghaus JP, Long M.C, Yashayaev I.
JournalGeophysical Research Letters
Volume44
Pagination9901-9909
Date Published2017/10
Type of ArticleArticle
ISBN Number0094-8276
Accession NumberWOS:000413921300043
Keywordsexcess helium; exchange; ground-water; isotopes; labrador sea; ocean; seawater; solubility; ventilation; water formation
Abstract

Dissolved gas distributions are important because they influence oceanic habitats and Earth's climate, yet competing controls by biology and physics make gas distributions challenging to predict. Bubble-mediated gas exchange, temperature change, and varying atmospheric pressure all push gases away from equilibrium. Here we use new noble gas measurements from the Labrador Sea to demonstrate a technique to quantify physical processes. Our analysis shows that water-mass formation can be represented by a quasi steady state in which bubble fluxes and cooling push gases away from equilibrium balanced by diffusive gas exchange forcing gases toward equilibrium. We quantify the rates of these physical processes from our measurements, allowing direct comparison to gas exchange parameterizations, and predict the physically driven saturation of other gases. This technique produces predictions that reasonably match N-2/Ar observations and demonstrates that physical processes should force SF6 to be approximate to 6% more supersaturated than CFC-11 and CFC-12, impacting ventilation age calculations.

DOI10.1002/2017gl075123
Student Publication: 
No