Snowball Earth: ice thickness on the tropical ocean
[1] On the tropical oceans of a neo-Proterozoic Snowball Earth, snow-free ice would have existed in regions of net sublimation. Photosynthesis could have continued beneath this bare ice if it was sufficiently thin and sufficiently clear. The steady state ice thickness is determined by the necessity...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.296.7868 2023-05-15T18:18:34+02:00 Snowball Earth: ice thickness on the tropical ocean Stephen G. Warren Richard E. Br Thomas C. Grenfell Christopher P. Mckay The Pennsylvania State University CiteSeerX Archives 2002 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.296.7868 http://www.atmos.washington.edu/~sgw/PAPERS/2002_Snowball.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.296.7868 http://www.atmos.washington.edu/~sgw/PAPERS/2002_Snowball.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.atmos.washington.edu/~sgw/PAPERS/2002_Snowball.pdf text 2002 ftciteseerx 2016-01-07T21:49:46Z [1] On the tropical oceans of a neo-Proterozoic Snowball Earth, snow-free ice would have existed in regions of net sublimation. Photosynthesis could have continued beneath this bare ice if it was sufficiently thin and sufficiently clear. The steady state ice thickness is determined by the necessity to balance the upward conduction of heat with three subsurface heating rates: the heat flux from the ocean to the ice base, the latent heat of freezing to the ice base, and the solar energy absorbed within the ice. A preliminary study, using a broadband model for solar radiation and assuming a large freezing rate, had indicated that tropical ice might be only a few meters thick. Here we show that the vertical throughput of ice by surface sublimation and basal freezing would be too slow to keep the ice thin and that the broadband model had exaggerated the absorption depth of sunlight. We use a spectral model for solar absorption, computing radiative transfer at 60 wavelengths, considering absorption by the ice, and scattering by bubbles. With the spectral model, the computed ice thickness is much greater. For a solar flux of 320 W m 2 at the equatorial surface and expected albedo of 0.5 for bare sea ice, we find that surface temperatures below 12°C generate ice layers too thick for photosynthesis (>100 m). If the albedo were as low Text Sea ice Unknown |
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English |
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[1] On the tropical oceans of a neo-Proterozoic Snowball Earth, snow-free ice would have existed in regions of net sublimation. Photosynthesis could have continued beneath this bare ice if it was sufficiently thin and sufficiently clear. The steady state ice thickness is determined by the necessity to balance the upward conduction of heat with three subsurface heating rates: the heat flux from the ocean to the ice base, the latent heat of freezing to the ice base, and the solar energy absorbed within the ice. A preliminary study, using a broadband model for solar radiation and assuming a large freezing rate, had indicated that tropical ice might be only a few meters thick. Here we show that the vertical throughput of ice by surface sublimation and basal freezing would be too slow to keep the ice thin and that the broadband model had exaggerated the absorption depth of sunlight. We use a spectral model for solar absorption, computing radiative transfer at 60 wavelengths, considering absorption by the ice, and scattering by bubbles. With the spectral model, the computed ice thickness is much greater. For a solar flux of 320 W m 2 at the equatorial surface and expected albedo of 0.5 for bare sea ice, we find that surface temperatures below 12°C generate ice layers too thick for photosynthesis (>100 m). If the albedo were as low |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Stephen G. Warren Richard E. Br Thomas C. Grenfell Christopher P. Mckay |
spellingShingle |
Stephen G. Warren Richard E. Br Thomas C. Grenfell Christopher P. Mckay Snowball Earth: ice thickness on the tropical ocean |
author_facet |
Stephen G. Warren Richard E. Br Thomas C. Grenfell Christopher P. Mckay |
author_sort |
Stephen G. Warren |
title |
Snowball Earth: ice thickness on the tropical ocean |
title_short |
Snowball Earth: ice thickness on the tropical ocean |
title_full |
Snowball Earth: ice thickness on the tropical ocean |
title_fullStr |
Snowball Earth: ice thickness on the tropical ocean |
title_full_unstemmed |
Snowball Earth: ice thickness on the tropical ocean |
title_sort |
snowball earth: ice thickness on the tropical ocean |
publishDate |
2002 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.296.7868 http://www.atmos.washington.edu/~sgw/PAPERS/2002_Snowball.pdf |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
http://www.atmos.washington.edu/~sgw/PAPERS/2002_Snowball.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.296.7868 http://www.atmos.washington.edu/~sgw/PAPERS/2002_Snowball.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766195180261605376 |