Effects of the tropospheric large-scale circulation on European winter temperatures during the period of amplified Arctic warming

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http://hdl.handle.net/10138/314241

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Vihma , T , Graversen , R G , Chen , L , Handorf , D , Skific , N , Francis , J A , Tyrrell , N L , Hall , R , Hanna , E , Uotila , P , Dethloff , K , Karpechko , A , Björnsson , H & Overland , J E 2020 , ' Effects of the tropospheric large-scale circulation on European winter temperatures during the period of amplified Arctic warming ' , International Journal of Climatology , vol. 40 , no. 1 , pp. 509-529 . https://doi.org/10.1002/joc.6225

Title: Effects of the tropospheric large-scale circulation on European winter temperatures during the period of amplified Arctic warming
Author: Vihma, Timo; Graversen, Rune G.; Chen, Linling; Handorf, Dörthe; Skific, Natasa; Francis, Jennifer A.; Tyrrell, Nicholas L; Hall, Richard; Hanna, Edward; Uotila, Petteri; Dethloff, Klaus; Karpechko, Alexey; Björnsson, Halldor; Overland, James E.
Other contributor: University of Helsinki, INAR Physics
Date: 2020-01
Language: eng
Number of pages: 21
Belongs to series: International Journal of Climatology
ISSN: 0899-8418
DOI: https://doi.org/10.1002/joc.6225
URI: http://hdl.handle.net/10138/314241
Abstract: We investigate factors influencing European winter (DJFM) air temperatures for the period 1979-2015 with the focus on changes during the recent period of rapid Arctic warming (1998-2015). We employ meteorological reanalyses analysed with a combination of correlation analysis, two pattern clustering techniques, and back-trajectory airmass identification. In all five selected European regions, severe cold winter events lasting at least 4 days are significantly correlated with warm Arctic episodes. Relationships during opposite conditions of warm Europe/cold Arctic are also significant. Correlations have become consistently stronger since 1998. Large-scale pattern analysis reveals that cold spells are associated with the negative phase of the North Atlantic Oscillation (NAO-) and the positive phase of the Scandinavian (SCA+) pattern, which in turn are correlated with the divergence of dry-static energy transport. Warm European extremes are associated with opposite phases of these patterns and the convergence of latent heat transport. Airmass trajectory analysis is consistent with these findings, as airmasses associated with extreme cold events typically originate over continents, while warm events tend to occur with prevailing maritime airmasses. Despite Arctic-wide warming, significant cooling has occurred in northeastern Europe owing to a decrease in adiabatic subsidence heating in airmasses arriving from the southeast, along with increased occurrence of circulation patterns favouring low temperature advection. These dynamic effects dominated over the increased mean temperature of most circulation patterns. Lagged correlation analysis reveals that SCA- and NAO+ are typically preceded by cold Arctic anomalies during the previous 2-3 months, which may aid seasonal forecasting.
Subject: 114 Physical sciences
AMPLIFICATION
ATLANTIC CLIMATE VARIABILITY
ATMOSPHERIC CIRCULATION
Arctic
EXTREME WEATHER
European weather
IMPACT
MIDLATITUDE WEATHER
NORTH-ATLANTIC
North Atlantic oscillation
REGIMES
SEA-ICE REDUCTION
STRATOSPHERIC POLAR VORTEX
Scandinavian pattern
subsidence heating
teleconnections
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