The effect of sea-ice on the transient atmospheric eddies of the Southern Hemisphere |
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Authors: | C G Menéndez V Serafini H Le Treut |
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Institution: | (1) Centro de Investigaciones del Mar y la Atmósfera/CONICET-UBA Ciudad Universitaria, Pabellón 2, Piso 2, 1428 Buenos Aires, Argentina E-mail: menendez@at1.fcen.uba.ar, AR;(2) Laboratoire de Météorologie Dynamique/CNRS, Université P. et M. Curie, Tour 15-25, 4 place Jussieu, 75252 Paris Cedex 05, France, FR |
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Abstract: | Two 10 y simulations with a full seasonal cycle and 96×72×19 resolution were carried out with a version of the LMD GCM to
diagnose the role of sea-ice on the extratropical climatology of the Southern Hemisphere. The control integration used the
usual observed sea-ice distribution, while the anomaly simulation imposed a scenario in which all sea-ice was entirely replaced
by open ocean. The simulated control climate was compared with available observational-based analyses. Relevant diagnostics
of the time mean and indicators of the transient eddy activity have been evaluated for both integrations. The impact was shown
throughout the troposphere and was larger and more organised in winter. We found reduced westerly flow and both falls and
rises in sea level pressure in the region from which sea-ice was removed. The removal of ice in the Southern Ocean affects
the baroclinic structure of the atmosphere. Changes in baroclinicity and eddy activity are consistent with changes in the
mean climate. In general, the meridional wind variance, the poleward transient temperature flux and the eddy flux convergence
of westerly momentum were weaker over the Southern Ocean. However, a strengthening of the variance downstream of the subtropical
jet was found. The position of the main storm track tends to be slightly displaced equatorward in the anomaly case.
Received: 24 February 1998 / Accepted: 13 March 1999 |
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