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dc.contributor.authorUmmenhofer, Caroline C.  Concept link
dc.contributor.authorMcIntosh, Peter C.  Concept link
dc.contributor.authorPook, Michael J.  Concept link
dc.contributor.authorRisbey, James S.  Concept link
dc.date.accessioned2014-03-12T19:45:35Z
dc.date.available2014-10-22T08:57:26Z
dc.date.issued2013-11-01
dc.identifier.citationJournal of Climate 26 (2013): 8476–8494en_US
dc.identifier.urihttps://hdl.handle.net/1912/6482
dc.descriptionAuthor Posting. © American Meteorological Society, 2013. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 26 (2013): 8476–8494, doi:10.1175/JCLI-D-12-00860.1.en_US
dc.description.abstractCharacteristics of atmospheric blocking in the Southern Hemisphere (SH) are explored in atmospheric general circulation model (AGCM) simulations with the Community Atmosphere Model, version 3, with a particular focus on the Australia–New Zealand sector. Preferred locations of blocking in SH observations and the associated seasonal cycle are well represented in the AGCM simulations, but the observed magnitude of blocking is underestimated throughout the year, particularly in late winter and spring. This is related to overly zonal flow due to an enhanced meridional pressure gradient in the model, which results in a decreased amplitude of the longwave trough/ridge pattern. A range of AGCM sensitivity experiments explores the effect on SH blocking of tropical heating, midlatitude sea surface temperatures, and land–sea temperature gradients created over the Australian continent during austral winter. The combined effects of tropical heating and extratropical temperature gradients are further explored in a configuration that is favorable for blocking in the Australia–New Zealand sector with warm SST anomalies to the north of Australia, cold to the southwest of Australia, warm to the southeast, and cool Australian land temperatures. The blocking-favorable configuration indicates a significant strengthening of the subtropical jet and a reduction in midlatitude flow, which results from changes in the thermal wind. While these overall changes in mean climate, predominantly forced by the tropical heating, enhance blocking activity, the magnitude of atmospheric blocking compared to observations is still underestimated. The blocking-unfavorable configuration with surface forcing anomalies of opposite sign results in a weakening subtropical jet, enhanced midlatitude flow, and significantly reduced blocking.en_US
dc.description.sponsorshipC.C.U. received support from the Australian Research Council through funding awarded to the Centre of Excellence for Climate System Science and the Penzance Endowed Fund at WHOI. P.C.M., M.J.P., and J.S.R. were funded by the CSIRO Climate Adaptation Flagship and the Managing Climate Variability R&D Program.en_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherAmerican Meteorological Societyen_US
dc.relation.urihttps://doi.org/10.1175/JCLI-D-12-00860.1
dc.subjectAustraliaen_US
dc.subjectSouthern Hemisphereen_US
dc.subjectAtmosphere-ocean interactionen_US
dc.subjectAtmospheric circulationen_US
dc.subjectBlockingen_US
dc.subjectGeneral circulation modelsen_US
dc.titleImpact of surface forcing on Southern Hemisphere atmospheric blocking in the Australia–New Zealand sectoren_US
dc.typeArticleen_US
dc.description.embargo2014-05-01en_US
dc.identifier.doi10.1175/JCLI-D-12-00860.1


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