Tropical forcing of increased Southern Ocean climate variabi

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TitleTropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperature reconstructionAbstractOccupying about 14% of the world's surface, the Southern Ocean plays a fundamental role in ocean and atmosphere circulation, carbon cycling and Antarctic ice-sheet dynamics. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine-atmosphere-ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52-54°S). Our annually resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the 1940s, a phenomenon predating the observational record. Climate reanalysis and modelling show a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer. Our results suggest that modern observed high interannual variability was established across the mid-twentieth century, and that the influence of contemporary equatorial Pacific temperatures may now be a permanent feature across the mid- to high latitudes. © Author(s) 2017.Funding DetailsDE130101336, ARC, Australian Research Council; DP130104156, ARC, Australian Research Council; FT120100004, ARC, Australian Research Council; FL100100195, ARC, Australian Research Council; UNSW, University of New South Wales

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1st AuthorTurney, C. AuthorTurney, C.Fogwill, C.Palmer, J.Van Sebille, E.Thomas, Z.McGlone, M.Richardson, S.Wilmshurst, J.Fenwick, P.Zunz, V.Goosse, H.Wilson, K.-J.Carter, L.Lipson, M.Jones, R.Harsch, M.Clark, G.Marzinelli, E.Rogers, T.Rainsley, E.Ciasto, L.Waterman, S.Thomas, E.Visbeck, M.Year2017JournalClimate of the PastVolume13Number3Pages231-248DOI10.5194/cp-13-231-2017URLhttps://www.scopus.com/inward/recor.....9e51292d9027047c0b3f6950aPublisherCopernicus GmbHKeywordsannual variationanthropogenic effectatmosphere-ice-ocean systemclimate forcingclimate variationinstrumentationpaleotemperaturereconstructionRossby wavesea surface temperatureSouthern Hemispheresubantarctic regiontropical environmenttwentieth century, Pacific OceanSouthern Ocean

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CitationTurney, C., Fogwill, C., Palmer, J., Van Sebille, E., Thomas, Z., McGlone, M., Richardson, S., Wilmshurst, J., Fenwick, P., Zunz, V., Goosse, H., Wilson, K.-J., Carter, L., Lipson, M., Jones, R., Harsch, M., Clark, G., Marzinelli, E., Rogers, T., Rainsley, E., Ciasto, L., Waterman, S., Thomas, E. and Visbeck, M. (2017). Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperature reconstruction. Climate of the Past, 13(3): 231-248Antarctica NZ supported?YesNZARI?No