Tropospheric circulation during the early twentieth century Arctic warming

Wegmann, Martin; Brönnimann, Stefan; Compo, Gilbert P. (2017). Tropospheric circulation during the early twentieth century Arctic warming. Climate dynamics, 48(7-8), pp. 2405-2418. Springer 10.1007/s00382-016-3212-6

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The early twentieth century Arctic warming (ETCAW) between 1920 and 1940 is an exceptional feature of climate variability in the last century. Its warming rate was only recently matched by recent warming in the region. Unlike recent warming largely attributable to anthropogenic radiative forcing, atmospheric warming during the ETCAW was strongest in the mid-troposphere and is believed to be triggered by an exceptional case of natural climate variability. Nevertheless, ultimate mechanisms and causes for the ETCAW are still under discussion. Here we use state of the art multi-member global circulation models, reanalysis and reconstruction datasets to investigate the internal atmospheric dynamics of the ETCAW. We investigate the role of boreal winter mid-tropospheric heat transport and circulation in providing the energy for the large scale warming. Analyzing sensible heat flux components and regional differences, climate models are not able to reproduce the heat flux evolution found in reanalysis and reconstruction datasets. These datasets show an increase of stationary eddy heat flux and a decrease of transient eddy heat flux during the ETCAW. Moreover, tropospheric circulation analysis reveals the important role of both the Atlantic and the Pacific sectors in the convergence of southerly air masses into the Arctic during the warming event. Subsequently, it is suggested that the internal dynamics of the atmosphere played a major role in the formation in the ETCAW.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Climatology
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography
08 Faculty of Science > Institute of Geography > Physical Geography

UniBE Contributor:

Wegmann, Martin and Brönnimann, Stefan

ISSN:

0930-7575

Publisher:

Springer

Language:

English

Submitter:

Céline Dizerens

Date Deposited:

04 Aug 2016 12:37

Last Modified:

17 May 2017 09:52

Publisher DOI:

10.1007/s00382-016-3212-6

BORIS DOI:

10.7892/boris.85305

URI:

https://boris.unibe.ch/id/eprint/85305

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