The impact of a changing Southern Hemisphere Annular Mode on Antarctic Peninsula summer temperatures

Marshall, Gareth J. ORCID:; Orr, Andrew; van Lipzig, Nicole P.M.; King, John C. ORCID: 2006 The impact of a changing Southern Hemisphere Annular Mode on Antarctic Peninsula summer temperatures. Journal of Climate, 19 (20). 5388-5404.

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Since the mid-1960s, rapid regional summer warming has occurred on the east coast of the northern Antarctic Peninsula, with near-surface temperatures increasing by more than 2°C. This warming has contributed significantly to the collapse of the northern sections of the Larsen Ice Shelf. Coincident with this warming, the summer Southern Hemisphere Annular Mode (SAM) has exhibited a marked trend, suggested by modeling studies to be predominantly a response to anthropogenic forcing, resulting in increased westerlies across the northern peninsula. Observations and reanalysis data are utilized to demonstrate that the changing SAM has played a key role in driving this local summer warming. It is proposed that the stronger summer westerly winds reduce the blocking effect of the Antarctic Peninsula and lead to a higher frequency of air masses being advected eastward over the orographic barrier of the northern Antarctic Peninsula. When this occurs, a combination of a climatological temperature gradient across the barrier and the formation of a föhn wind on the lee side typically results in a summer near-surface temperature sensitivity to the SAM that is 3 times greater on the eastern side of the peninsula than on the west. SAM variability is also shown to play a less important role in determining summer temperatures at stations west of the barrier in the northern peninsula (62°S), both at the surface and throughout the troposphere. This is in contrast to a station farther south (65°S) where the SAM exerts little influence.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Antarctic Climate and the Earth System
ISSN: 0894-8755
Additional Information. Not used in RCUK Gateway to Research.: Full text not available from this repository
Additional Keywords: Climate change, Warming
NORA Subject Terms: Meteorology and Climatology
Atmospheric Sciences
Date made live: 10 Sep 2007 13:41 +0 (UTC)

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