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Author Rose, Brian E. J. ♦ Cronin, Timothy W. ♦ Bitz, Cecilia M.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ♦ ALBEDO ♦ ANALYTICAL SOLUTION ♦ DISTRIBUTION ♦ ENERGY BALANCE ♦ EQUATOR ♦ EQUILIBRIUM ♦ FEEDBACK ♦ INSOLATION ♦ INSTABILITY ♦ NUMERICAL SOLUTION ♦ PLANETS ♦ RADIANT HEAT TRANSFER ♦ RADIATIVE FORCING ♦ SPACE ♦ STABILITY ♦ WATER
Abstract Planetary obliquity determines the meridional distribution of the annual mean insolation. For obliquity exceeding 55°, the weakest insolation occurs at the equator. Stable partial snow and ice cover on such a planet would be in the form of a belt about the equator rather than polar caps. An analytical model of planetary climate is used to investigate the stability of ice caps and ice belts over the widest possible range of parameters. The model is a non-dimensional diffusive Energy Balance Model, representing insolation, heat transport, and ice−albedo feedback on a spherical planet. A complete analytical solution for any obliquity is given and validated against numerical solutions of a seasonal model in the “deep-water” regime of weak seasonal ice line migration. Multiple equilibria and unstable transitions between climate states (ice-free, Snowball, or ice cap/belt) are found over wide swaths of parameter space, including a “Large Ice-Belt Instability” and “Small Ice-Belt Instability” at high obliquity. The Snowball catastrophe is avoided at weak radiative forcing in two different scenarios: weak albedo feedback and inefficient heat transport (favoring stable partial ice cover), or efficient transport at high obliquity (favoring ice-free conditions). From speculative assumptions about distributions of planetary parameters, three-fourths to four-fifths of all planets with stable partial ice cover should be in the form of Earth-like polar caps.
ISSN 0004637X
Educational Use Research
Learning Resource Type Article
Publisher Date 2017-09-01
Publisher Place United States
Journal Astrophysical Journal
Volume Number 846
Issue Number 1


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