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Stability of weather regimes during the last millennium from climate simulations
Author(s) -
Yiou Pascal,
Servonnat Jérôme,
Yoshimori Masakazu,
Swingedouw Didier,
Khodri Myriam,
AbeOuchi Ayako
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl051310
Subject(s) - climatology , proxy (statistics) , atmospheric circulation , north atlantic oscillation , climate change , little ice age , climate model , environmental science , atmospheric dynamics , general circulation model , period (music) , geography , atmospheric sciences , atmosphere (unit) , geology , meteorology , oceanography , machine learning , computer science , physics , acoustics
The variability of the extra‐tropical atmospheric circulation and its potential dependence on external forcings have been debated topics in climate modeling and observation communities. A recent reconstruction of the North Atlantic Oscillation Index has argued that the Medieval Warm Period period yielded a persistent positive phase of this index in contrast with an oscillating mode during the Little Ice Age. This paper tests whether this feature can be obtained, in millennium simulations from three different climate models. We examine the daily atmospheric dynamics that drives the main modes of extra‐tropical variability. We find that the transition from a Medieval Warm Period to a Little Ice Age in the North Atlantic does not imply changes in patterns or frequency of weather regimes, although the mean surface temperature change is significant. This implies that the interpretation of proxy records in terms of atmospheric variability should be revised in order to take into account the structure of daily meteorological patterns, and/or climate models are too constrained to infer large changes of atmospheric variability.