Mediterranean climate change and Indian Ocean warming

Hoerling, M. and Hurrell, J. and Eischeid, J. (2006) Mediterranean climate change and Indian Ocean warming. Il nuovo cimento C, 29 (1). pp. 99-104. ISSN 1826-9885

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General circulation model (GCM) responses to 20th century changes in sea surface temperatures (SSTs) and greenhouse gases are diagnosed, with emphasis on their relationship to observed regional climate change over the Mediterranean region. A major question is whether the Mediterranean region’s drying trend since 1950 can be understood as a consequence of the warming trend in tropical SSTs. We focus on the impact of Indian Ocean warming, which is itself the likely result of increasing greenhouse gases. It is discovered that a strong projection onto the positive polarity of the North Atlantic Oscillation (NAO) index characterizes the atmospheric response structure to the 1950-1999 warming of Indian Ocean SSTs. This influence appears to be robust in so far as it is reproduced in ensembles of experiments using three different GCMs. Both the equilibrium and transient responses to Indian Ocean warming are examined. Under each scenario, the latitude of prevailing midlatitude westerlies shifts poleward during the November-April period. The consequence is a drying of the Mediterranean region, whereas northern Europe and Scandinavia receive increased precipitation in concert with the poleward shift of storminess. The IPCC (TAR) 20th century coupled ocean-atmosphere simulations forced by observed greenhouse gas changes also yield a post-1950 drying trend over the Mediterranean. We argue that this feature of human-induced regional climate change is the outcome of a dynamical feedback, one involving Indian Ocean warming and a requisite adjustment of atmospheric circulation systems to such ocean warming.

Item Type: Article
Additional Information: Paper presented at the Workshop on “Historical Reconstruction of Climate Variability and Change in Mediterranean Regions”, Bologna, October 5-6, 2004.
Uncontrolled Keywords: Climatology ; Climate dynamics ; Indian Ocean
Subjects: 500 Scienze naturali e Matematica > 550 Scienze della Terra > 551.6 Climatologia e tempo atmosferico (Classificare qui i lo studio dei Cambiamenti climatici)
Depositing User: Marina Spanti
Date Deposited: 18 Mar 2020 16:21
Last Modified: 18 Mar 2020 16:21

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