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Author Levi, A. ♦ Sasselov, D. ♦ Podolak, M.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ♦ ABUNDANCE ♦ CARBON DIOXIDE ♦ DEPOSITION ♦ FEEDBACK ♦ GREENHOUSE EFFECT ♦ ICE ♦ LIQUIDS ♦ MASS ♦ PLANETS ♦ REDUCTION ♦ SATELLITE ATMOSPHERES ♦ SATELLITES ♦ SATURATION ♦ SEAS ♦ STEADY-STATE CONDITIONS ♦ SURFACES ♦ WATER
Abstract We consider super-Earth sized planets which have a water mass fraction large enough to form an external mantle composed of high-pressure water-ice polymorphs and also lack a substantial H/He atmosphere. We consider such planets in their habitable zone, so that their outermost condensed mantle is a global, deep, liquid ocean. For these ocean planets, we investigate potential internal reservoirs of CO{sub 2}, the amount of CO{sub 2} dissolved in the ocean for the various saturation conditions encountered, and the ocean-atmosphere exchange flux of CO{sub 2}. We find that, in a steady state, the abundance of CO{sub 2} in the atmosphere has two possible states. When wind-driven circulation is the dominant CO{sub 2} exchange mechanism, an atmosphere of tens of bars of CO{sub 2} results, where the exact value depends on the subtropical ocean surface temperature and the deep ocean temperature. When sea-ice formation, acting on these planets as a CO{sub 2} deposition mechanism, is the dominant exchange mechanism, an atmosphere of a few bars of CO{sub 2} is established. The exact value depends on the subpolar surface temperature. Our results suggest the possibility of a negative feedback mechanism, unique to water planets, where a reduction in the subpolar temperature drives more CO{sub 2} into the atmosphere to increase the greenhouse effect.
ISSN 0004637X
Educational Use Research
Learning Resource Type Article
Publisher Date 2017-03-20
Publisher Place United States
Journal Astrophysical Journal
Volume Number 838
Issue Number 1


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