1706 JOURNAL OF CLIMATE VOLUME 19 Ice Age Winds: An Aquaplanet Model
Factors controlling the position and strength of the surface winds during the Last Glacial Maximum (LGM) are examined using a global, multilevel, moist, atmospheric model. The idealized aquaplanet model is bounded below by a prescribed axisymmetric temperature distribution that corresponds to an oce...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.144.1146 2023-05-15T18:18:47+02:00 1706 JOURNAL OF CLIMATE VOLUME 19 Ice Age Winds: An Aquaplanet Model Gareth P. Williams Kirk Bryan The Pennsylvania State University CiteSeerX Archives 2005 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.144.1146 http://www.gfdl.noaa.gov/reference/bibliography/2006/gw0602.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.144.1146 http://www.gfdl.noaa.gov/reference/bibliography/2006/gw0602.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.gfdl.noaa.gov/reference/bibliography/2006/gw0602.pdf text 2005 ftciteseerx 2016-01-07T15:03:59Z Factors controlling the position and strength of the surface winds during the Last Glacial Maximum (LGM) are examined using a global, multilevel, moist, atmospheric model. The idealized aquaplanet model is bounded below by a prescribed axisymmetric temperature distribution that corresponds to an oceancovered surface. Various forms of this distribution are used to examine the influence of changes in the surface cooling and baroclinicity rates. The model omits seasonal variations. Increasing the cooling lowers the tropopause and greatly reduces the moist convection in the Tropics, thereby causing a weakening and equatorward contraction of the Hadley cell. Such a cooling also weakens the surface westerlies and shifts the peak westerly stress equatorward. An extra surface baroclinicity in midlatitudes—implicitly associated with an increase in the polar sea ice—also shifts the peak westerly stress equatorward, but strengthens the surface westerlies. Thus, calculations with combined surface cooling and baroclinicity increases, representative of the Last Glacial Maximum, reveal an absence of change in the amplitude of the peak westerly stress but exhibit a substantial equatorward shift in its position, 7 ° for a 3-K cooling and 11 ° for a 6-K cooling. The easterlies, however, always increase in strength when the surface westerlies move equatorward. The application of these results to the LGM must take into account the model’s assumption of symmetry between the two hemispheres. Any changes in the climate’s hemispheric asymmetry could also cause comparable latitudinal shifts in the westerlies, probably of opposite sign in the two hemispheres. Published coupled-model simulations for the LGM give an equatorward shift for the peak westerlies in the Northern Hemisphere but give contradictory results for the Southern Hemisphere. 1. Text Sea ice Unknown |
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English |
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Factors controlling the position and strength of the surface winds during the Last Glacial Maximum (LGM) are examined using a global, multilevel, moist, atmospheric model. The idealized aquaplanet model is bounded below by a prescribed axisymmetric temperature distribution that corresponds to an oceancovered surface. Various forms of this distribution are used to examine the influence of changes in the surface cooling and baroclinicity rates. The model omits seasonal variations. Increasing the cooling lowers the tropopause and greatly reduces the moist convection in the Tropics, thereby causing a weakening and equatorward contraction of the Hadley cell. Such a cooling also weakens the surface westerlies and shifts the peak westerly stress equatorward. An extra surface baroclinicity in midlatitudes—implicitly associated with an increase in the polar sea ice—also shifts the peak westerly stress equatorward, but strengthens the surface westerlies. Thus, calculations with combined surface cooling and baroclinicity increases, representative of the Last Glacial Maximum, reveal an absence of change in the amplitude of the peak westerly stress but exhibit a substantial equatorward shift in its position, 7 ° for a 3-K cooling and 11 ° for a 6-K cooling. The easterlies, however, always increase in strength when the surface westerlies move equatorward. The application of these results to the LGM must take into account the model’s assumption of symmetry between the two hemispheres. Any changes in the climate’s hemispheric asymmetry could also cause comparable latitudinal shifts in the westerlies, probably of opposite sign in the two hemispheres. Published coupled-model simulations for the LGM give an equatorward shift for the peak westerlies in the Northern Hemisphere but give contradictory results for the Southern Hemisphere. 1. |
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The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Gareth P. Williams Kirk Bryan |
spellingShingle |
Gareth P. Williams Kirk Bryan 1706 JOURNAL OF CLIMATE VOLUME 19 Ice Age Winds: An Aquaplanet Model |
author_facet |
Gareth P. Williams Kirk Bryan |
author_sort |
Gareth P. Williams |
title |
1706 JOURNAL OF CLIMATE VOLUME 19 Ice Age Winds: An Aquaplanet Model |
title_short |
1706 JOURNAL OF CLIMATE VOLUME 19 Ice Age Winds: An Aquaplanet Model |
title_full |
1706 JOURNAL OF CLIMATE VOLUME 19 Ice Age Winds: An Aquaplanet Model |
title_fullStr |
1706 JOURNAL OF CLIMATE VOLUME 19 Ice Age Winds: An Aquaplanet Model |
title_full_unstemmed |
1706 JOURNAL OF CLIMATE VOLUME 19 Ice Age Winds: An Aquaplanet Model |
title_sort |
1706 journal of climate volume 19 ice age winds: an aquaplanet model |
publishDate |
2005 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.144.1146 http://www.gfdl.noaa.gov/reference/bibliography/2006/gw0602.pdf |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
http://www.gfdl.noaa.gov/reference/bibliography/2006/gw0602.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.144.1146 http://www.gfdl.noaa.gov/reference/bibliography/2006/gw0602.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766195486072504320 |