North Atlantic – European weather regimes in a changing climate: present and future

2020 ◽  
Author(s):  
Luise J. Fischer ◽  
Dominik Büeler ◽  
Christian M. Grams ◽  
Urs Beyerle ◽  
David N. Bresch ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Climate Model ◽  
Future Climate ◽  
Climate Projections ◽  
Climate Conditions ◽  
Weather Regimes ◽  
The North ◽  
Surface Weather ◽  
The North Atlantic

<p>We present findings from an analysis of weather regimes over the North Atlantic and Europe in present and future climate conditions. Weather regimes strongly influence the statistical distribution of surface weather variables. We use a recently developed, all-season North Atlantic - European weather regime classification with seven regimes. These regimes were originally identified in ERA-Interim reanalyses and, in this study, we investigate how they are represented in climate simulations using the CESM1 large ensemble for present-day and future (RCP8.5) climate conditions. With these regimes, the classification of the flow conditions in the considered region goes beyond the classical categorization according to the North Atlantic oscillation index; the weather regimes explicitly capture different flavors of strong zonal flows and the occurrence of blocking over Greenland, Scandinavia, and Central Europe, respectively. In ERA-Interim they explain 70% of the variability in geopotential height at 500 hPa year-round. Our analysis quantifies how well CESM1 represents the statistics of the weather regimes in present-day climate and how strongly their frequencies change in the future climate scenario. In addition, we identify statistical relationships between weather regimes and their resulting impacts on spatial patterns of surface variables such as precipitation. We compare those patterns and characteristics of the weather regimes identified in ERA-Interim to their characteristics in simulations of present and future climate conditions.</p><p>This analysis leads to insight into the representation of and changes in atmospheric circulation in one particular climate model, and, at the same time, it quantifies how well the climate model captures the observed link between surface weather and weather regimes. This approach contributes to improving our understanding of atmospheric circulation changes and their impact on a regional scale, and it may benefit the interpretation and communication of climate projections.</p>

scholarly journals Impacts of the North Atlantic Warming Hole in Future Climate Projections: Mean Atmospheric Circulation and the North Atlantic Jet

2019 ◽  
Vol 32 (10) ◽  
pp. 2673-2689 ◽  
Author(s):  
Melissa Gervais ◽  
Jeffrey Shaman ◽  
Yochanan Kushnir
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Forced Response ◽  
Future Climate ◽  
Climate Projections ◽  
Transient Eddy ◽  
The North ◽  
Climate Simulations ◽  
The North Atlantic ◽  
The Impact

Abstract In future climate simulations there is a pronounced region of reduced warming in the subpolar gyre of the North Atlantic Ocean known as the North Atlantic warming hole (NAWH). This study investigates the impact of the North Atlantic warming hole on atmospheric circulation and midlatitude jets within the Community Earth System Model (CESM). A series of large-ensemble atmospheric model experiments with prescribed sea surface temperature (SST) and sea ice are conducted, in which the warming hole is either filled or deepened. Two mechanisms through which the NAWH impacts the atmosphere are identified: a linear response characterized by a shallow atmospheric cooling and increase in sea level pressure shifted slightly downstream of the SST changes, and a transient eddy forced response whereby the enhanced SST gradient produced by the NAWH leads to increased transient eddy activity that propagates vertically and enhances the midlatitude jet. The relative contributions of these two mechanisms and the details of the response are strongly dependent on the season, time period, and warming hole strength. Our results indicate that the NAWH plays an important role in midlatitude atmospheric circulation changes in CESM future climate simulations.

Surface temperatures of the Mid-Pliocene North Atlantic Ocean: implications for future climate

2008 ◽  
Vol 367 (1886) ◽  
pp. 69-84 ◽  
Author(s):  
Harry J Dowsett ◽  
Mark A Chandler ◽  
Marci M Robinson
Keyword(s):  
Climate Change ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Climate Model ◽  
North Atlantic Ocean ◽  
Future Climate ◽  
First Century ◽  
Sea Surface ◽  
The North ◽  
The North Atlantic

The Mid-Pliocene is the most recent interval in the Earth's history to have experienced warming of the magnitude predicted for the second half of the twenty-first century and is, therefore, a possible analogue for future climate conditions. With continents basically in their current positions and atmospheric CO 2 similar to early twenty-first century values, the cause of Mid-Pliocene warmth remains elusive. Understanding the behaviour of the North Atlantic Ocean during the Mid-Pliocene is integral to evaluating future climate scenarios owing to its role in deep water formation and its sensitivity to climate change. Under the framework of the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) sea surface reconstruction, we synthesize Mid-Pliocene North Atlantic studies by PRISM members and others, describing each region of the North Atlantic in terms of palaeoceanography. We then relate Mid-Pliocene sea surface conditions to expectations of future warming. The results of the data and climate model comparisons suggest that the North Atlantic is more sensitive to climate change than is suggested by climate model simulations, raising the concern that estimates of future climate change are conservative.

scholarly journals Evaluating climate model performance with various parameter sets using observations over the last centuries

2010 ◽  
Vol 6 (2) ◽  
pp. 711-765 ◽  
Author(s):  
M. F. Loutre ◽  
A. Mouchet ◽  
T. Fichefet ◽  
H. Goosse ◽  
H. Goelzer ◽  
...  
Keyword(s):  
North Atlantic ◽  
Climate Model ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Climate Projections ◽  
Freshwater Flux ◽  
The North ◽  
Climate Simulations ◽  
Wide Range ◽  
The North Atlantic

Abstract. Many sources of uncertainties limit the accuracy and precision of climate projections. Here, we focus on the parameter uncertainty, i.e. the imperfect knowledge of the values of many physical parameters in a climate model. We use LOVECLIM, a global three-dimensional Earth system model of intermediate complexity and vary several parameters within their range of uncertainty. Nine climatic parameter sets and three carbon cycle parameter sets are identified. They all yield present climate simulations coherent with observations and they cover a wide range of climate responses to doubled atmospheric CO2 concentration and freshwater flux in the North Atlantic sensitivity experiments. They also simulate a large range of atmospheric CO2 concentrations in response to prescribed emissions. Climate simulations of the last millennium are performed with the 27 combinations of these parameter sets. A special attention is given to the ability of LOVECLIM to reproduce the evolution of several climate variables over the last few decades, for which observations are available. The model response, even its ocean component, is strongly dominated by the model sensitivity to an increase in atmospheric CO2 concentration but much slightly by its sensitivity to freshwater flux in the North Atlantic. The whole set of parameter sets leads to a wide range of simulated climates. Although only some parameter sets yield simulations that reproduce the observed key variables of the climate system over the last decades, all of them could be used to characterise extreme climate projections.

The mutual impact of weather regimes and the stratospheric circulation on European surface weather

2020 ◽  
Author(s):  
Christian M. Grams ◽  
Remo Beerli ◽  
Dominik Büeler ◽  
Daniela I. V. Domeisen ◽  
Lukas Papritz ◽  
...  
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Polar Vortex ◽  
Stratospheric Polar Vortex ◽  
Weather Regimes ◽  
The North ◽  
Weather Events ◽  
Surface Weather ◽  
The North Atlantic ◽  
Large Scale Flow

<p>Extreme states of the winter stratosphere, such as sudden stratospheric warmings (SSWs) or an extremely strong stratospheric polar vortex (SPV), can affect surface weather over the North-Atlantic European region on subseasonal time scales. Here we investigate the occurrence of Atlantic-European weather regimes during different stratospheric conditions in winter and their link to large-scale weather events in European sub-regions. We further elucidate if the large-scale flow regime in the North Atlantic at SSW onset determines the subsequent downward impact.</p><p>Anomalous stratospheric conditions modulate the occurrence of weather regimes which project strongly onto the NAO and the likelihood of their associated weather events. In contrast weather regimes which do not project strongly onto the NAO are not affected by anomalous stratospheric conditions. These regimes provide pathways to unexpected weather events in extreme stratospheric polar vortex states. For example, Greenland blocking (GL) and the Atlantic Trough (AT) regime are the most frequent large-scale flow patterns following SSWs. While in Central Europe GL provides a pathway to cold and calm weather, AT provides a pathway to warm and windy weather. The latter weather conditions are usually not expected after an SSW. Furthermore, we find that a blocking situation over western Europe and the North Sea (European Blocking) at the time of the SSW onset favours the GL response and associated cold conditions over Europe. In contrast, an AT response and mild conditions are more likely if GL occurs already at SSW onset. An assessment of forecast performance in ECMWF extended-range reforecasts suggests that the model tends to forecast too cold conditions following weak SPV states.</p><p>In summary, weather regimes and their response to anomalous SPV states importantly modulate the stratospheric impact on European surface weather. In particular the tropospheric impact of SSW events critically depends on the tropospheric state during the onset of the SSW. We conclude that a correct representation of weather regime life cycles in numerical models could provide crucial guidance for subseasonal prediction.</p><p> </p><p>References:</p><p>Beerli, R., and C. M. Grams, 2019: Stratospheric modulation of the large-scale circulation in the Atlantic–European region and its implications for surface weather events. Q.J.R. Meteorol. Soc., <strong>145</strong>, 3732–3750, doi:10.1002/qj.3653.</p><p>Domeisen, D. I. V., C. M. Grams, and L. Papritz, 2020: The role of North Atlantic-European weather regimes in the surface impact of sudden stratospheric warming events. Weather and Climate Dynamics Discussions, 1–24, doi:https://doi.org/10.5194/wcd-2019-16.</p>

scholarly journals Serial clustering of extratropical cyclones over the North Atlantic and Europe under recent and future climate conditions

2013 ◽  
Vol 118 (22) ◽  
pp. 12,476-12,485 ◽  
Author(s):  
Joaquim G. Pinto ◽  
Nina Bellenbaum ◽  
Melanie K. Karremann ◽  
Paul M. Della-Marta
Keyword(s):  
North Atlantic ◽  
Future Climate ◽  
Extratropical Cyclones ◽  
Climate Conditions ◽  
The North ◽  
The North Atlantic

scholarly journals The use of a flow field correction technique for alleviating the North Atlantic cold bias with application to the Kiel Climate Model

2015 ◽  
Vol 65 (8) ◽  
pp. 1079-1093 ◽  
Author(s):  
Annika Drews ◽  
Richard J. Greatbatch ◽  
Hui Ding ◽  
Mojib Latif ◽  
Wonsun Park
Keyword(s):  
Flow Field ◽  
North Atlantic ◽  
Climate Model ◽  
Cold Bias ◽  
The North ◽  
Correction Technique ◽  
The North Atlantic

Wave climate projections for Ireland for the end of the 21st century including analysis of EC-Earth winds over the North Atlantic Ocean

2016 ◽  
Vol 36 (14) ◽  
pp. 4592-4607 ◽  
Author(s):  
Sarah Gallagher ◽  
Emily Gleeson ◽  
Roxana Tiron ◽  
Ray McGrath ◽  
Frédéric Dias
Keyword(s):  
Atlantic Ocean ◽  
21St Century ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Wave Climate ◽  
Climate Projections ◽  
The North ◽  
The North Atlantic

Changes in Atmospheric Circulation and Ocean Ice Cover over the North Atlantic During the Last 41,000 Years

Science ◽  
1994 ◽  
Vol 263 (5154) ◽  
pp. 1747-1751 ◽  
Author(s):  
P. A. Mayewski ◽  
L. D. Meeker ◽  
S. Whitlow ◽  
M. S. Twickler ◽  
M. C. Morrison ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Ice Cover ◽  
The North ◽  
The North Atlantic

Subpolar Gyre – AMOC – Atmosphere Interactions on Multidecadal Timescales in a Version of the Kiel Climate Model

2021 ◽  
Author(s):  
Jing Sun ◽  
Mojib Latif ◽  
Wonsun Park
Keyword(s):  
North Atlantic ◽  
Climate Model ◽  
Deep Convection ◽  
Meridional Overturning Circulation ◽  
Subpolar Gyre ◽  
Surface Salinity ◽  
The North ◽  
Ocean Coupling ◽  
Meridional Overturning ◽  
The North Atlantic

<p>There is a controversy about the nature of multidecadal climate variability in the North Atlantic (NA) region, concerning the roles of ocean circulation and atmosphere-ocean coupling. Here we describe NA multidecadal variability from a version of the Kiel Climate Model, in which both subpolar gyre (SPG)-Atlantic Meridional Overturning Circulation (AMOC) and atmosphere-ocean coupling are essential. The oceanic barotropic streamfuntions, meridional overturning streamfunctions, and sea level pressure are jointly analyzed to derive the leading mode of Atlantic variability. This mode accounting for about 23.7 % of the total combined variance is oscillatory with an irregular periodicity of 25-50 years and an e-folding time of about a decade. SPG and AMOC mutually influence each other and together provide the delayed negative feedback necessary for maintaining the oscillation. An anomalously strong SPG, for example, drives higher surface salinity and density in the NA’s sinking region. In response, oceanic deep convection and AMOC intensify, which, with a time delay of about a decade, reduces SPG strength by enhancing upper-ocean heat content. The weaker gyre circulation leads to lower surface salinity and density in the sinking region, which eventually reduces deep convection and AMOC strength. There is a positive ocean-atmosphere feedback between the sea surface temperature and low-level atmospheric circulation over the Southern Greenland area, with related wind stress changes reinforcing SPG changes, thereby maintaining the (damped) multidecadal oscillation against dissipation. Stochastic surface heat-flux forcing associated with the North Atlantic Oscillation drives the eigenmode.</p>

scholarly journals The link between eddy-driven jet variability and weather regimes in the North Atlantic-European sector

2017 ◽  
Vol 143 (708) ◽  
pp. 2960-2972 ◽  
Author(s):  
Erica Madonna ◽  
Camille Li ◽  
Christian M. Grams ◽  
Tim Woollings
Keyword(s):  
North Atlantic ◽  
Weather Regimes ◽  
The North ◽  
The North Atlantic ◽  
Jet Variability ◽  
European Sector
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