scholarly journals Associations between large-scale atmospheric circulation and polar low developments over the North Atlantic during winter

2007 ◽  
Vol 112 (D12) ◽  
Author(s):  
Chantal Claud ◽  
Bertrand Duchiron ◽  
Pascal Terray
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Large Scale ◽  
The North ◽  
Polar Low ◽  
The North Atlantic ◽  
Large Scale Atmospheric Circulation

Impact of large-scale atmospheric circulation changes over the North Atlantic on the wind climate of the Baltic Sea area for the period 1948/49-2018/19

2020 ◽  
Author(s):  
Piia Post ◽  
Andreas Lehmann
Keyword(s):  
Baltic Sea ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Large Scale ◽  
The Baltic Sea ◽  
The North ◽  
The North Atlantic ◽  
The Baltic ◽  
Sea Area ◽  
Large Scale Atmospheric Circulation

<p>A detailed assessment of climate variability of the Baltic Sea area for the period 1958-2008 (Lehmann et al. 2011) revealed that changes in the warming trend since the mid-1980s, were associated with changes in the large-scale atmospheric circulation over the North Atlantic. The analysis of winter sea level pressure (SLP) data highlighted considerable changes in intensification and location of storm tracks, in parallel with the eastward shift of the North Atlantic Oscillation (NAO) centres of action. Additionally, a seasonal shift of strong wind events from autumn to winter and early spring exists for the Baltic area. Lehmann et al. (2002) showed that different atmospheric circulation regimes force different circulation patterns in the Baltic Sea. Furthermore, as atmospheric circulation, to a large extent, controls patterns of water circulation and biophysical aspects relevant for biological production, such as the vertical distribution of temperature and salinity, alterations in weather regimes may severely impact the trophic structure and functioning of marine food webs (Hinrichsen et al. 2007). To understand the processes linking changes in the marine environment and climate variability, it is essential to investigate all components of the climate system which of course include also the large-scale atmospheric circulation. Now, since extended time series data (1948-2018) for additional 20 years are available, it is interesting to investigate recent changes/shifts of the large-scale atmospheric conditions and their impact on the wind climate over the Baltic Sea area.</p>

scholarly journals Dynamical Properties of the North Atlantic Atmospheric Circulation in the Past 150 Years in CMIP5 Models and the 20CRv2c Reanalysis

2018 ◽  
Vol 31 (15) ◽  
pp. 6097-6111 ◽  
Author(s):  
David Rodrigues ◽  
M. Carmen Alvarez-Castro ◽  
Gabriele Messori ◽  
Pascal Yiou ◽  
Yoann Robin ◽  
...  
Keyword(s):  
Dynamical Systems ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Large Scale ◽  
Cmip5 Models ◽  
Historical Period ◽  
Local Dimension ◽  
The North ◽  
The North Atlantic ◽  
Over Time

It is of fundamental importance to evaluate the ability of climate models to capture the large-scale atmospheric circulation patterns and, in the context of a rapidly increasing greenhouse forcing, the robustness of the changes simulated in these patterns over time. Here we approach this problem from an innovative point of view based on dynamical systems theory. We characterize the atmospheric circulation over the North Atlantic in the CMIP5 historical simulations (1851–2000) in terms of two instantaneous metrics: local dimension of the attractor and stability of phase-space trajectories. We then use these metrics to compare the models to the Twentieth Century Reanalysis version 2c (20CRv2c) over the same historical period. The comparison suggests that (i) most models capture to some degree the median attractor properties, and models with finer grids generally perform better; (ii) in most models the extremes in the dynamical systems metrics match large-scale patterns similar to those found in the reanalysis; (iii) changes in the attractor properties observed for the ensemble-mean 20CRv2c are artifacts resulting from inhomogeneities in the standard deviation of the ensemble over time; and (iv) the long-term trends in local dimension observed among the 56 members of the 20CR ensemble have the same sign as those observed in the CMIP5 multimodel mean, although the multimodel trend is much weaker.

scholarly journals Winter Midlatitude Cold Anomalies Linked to North Atlantic Sea Ice and SST Anomalies: The Pivotal Role of the Potential Vorticity Gradient

2019 ◽  
Vol 32 (13) ◽  
pp. 3957-3981 ◽  
Author(s):  
Xiaodan Chen ◽  
Dehai Luo
Keyword(s):  
North America ◽  
North Atlantic ◽  
High Latitude ◽  
Large Scale ◽  
Northern Europe ◽  
The North ◽  
Sst Cooling ◽  
The North Atlantic ◽  
Large Scale Atmospheric Circulation ◽  
Pv Gradient

Abstract This study establishes a linkage between the North Atlantic sea ice concentration (SIC) or sea surface temperature (SST) and cold anomalies over northern Europe and North America through the Greenland blocking (GB) change. It is revealed that the magnitude of the meridional potential vorticity (PV) gradient in the North Atlantic mid- to high latitudes plays a key role in whether strong cold anomalies occur over the North America (NA) or northern Europe (NE) or both, while it is related to the SIC change observed over Baffin Bay, Davis Strait, and the Labrador Sea (BDL collectively) and the North Atlantic SST anomaly. When the midlatitude Atlantic SST is strongly warm or when the BDL SIC anomaly is largely positive, there is a corresponding large PV gradient over the North Atlantic. In this case, no intense cold anomalies are seen over NA due to less westward movement and the short lifetime of GB. Instead, a relatively strong cold anomaly appears over western and southern Europe. Its prior large-scale atmospheric circulation is the positive phase of the North Atlantic Oscillation (NAO). Moreover, strong cold anomalies can simultaneously occur over NA and NE only when the PV gradient is small under the influence of large SIC decline or intense mid- to high-latitude SST cooling across the Gulf Stream Extension. Its prior large-scale atmospheric circulation is a negative NAO phase. Daily composites show that strong cold anomalies over NA occur along the northwest–southeast direction in the presence of large SIC decline, whereas strong cold anomalies occur in NA midlatitudes even in the absence of large BDL SIC decline when mid- to high-latitude SST cooling is strong.

scholarly journals Springtime connections between the large-scale sea-level pressure field and gust wind speed over Iberia and the Balearics

2011 ◽  
Vol 11 (1) ◽  
pp. 191-203 ◽  
Author(s):  
M. L. Martín ◽  
F. Valero ◽  
A. Pascual ◽  
A. Morata ◽  
M. Y. Luna
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Large Scale ◽  
Pressure Field ◽  
Wind Gust ◽  
Sea Level Pressure ◽  
Wind Speeds ◽  
The North ◽  
Wind Gusts ◽  
The North Atlantic

Abstract. This paper investigates, by means of Singular Value Decomposition analysis, the springtime relationships between the mean sea-level pressure field over the North Atlantic and the regional wind gusts over the Iberian Peninsula, identifying the main atmospheric circulation patterns linked to gust wind speed anomaly configurations. The statistical significance of the obtained modes is investigated by means of Monte Carlo approach. The analysis highlighted that the covariability is dominated by two main large-scale features of the atmospheric circulation over the North Atlantic. The first mode relates to Iberian gust wind speeds to the Scandinavian pattern (SCAND), linking the large-scale pattern to above-normal wind gusts. The second covariability mode, associated with the North Atlantic Oscillation (NAO) pattern, correlates with maximum wind speeds over Iberia. An enhanced spring NAO pattern is related to positive (negative) wind gust correlations over northern (southern) Iberia. To find true relationships between large-scale atmospheric field and the gust wind speeds, composite maps were built up to give an average atmospheric circulation associated with coherent wind gust variability over Iberia.

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

Seasonal Predictability of Wintertime mid-latitude Cyclonic Activity over the North Atlantic and Europe

2021 ◽  
Author(s):  
Alvise Aranyossy ◽  
Sebastian Brune ◽  
Lara Hellmich ◽  
Johanna Baehr
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Jet Stream ◽  
Cyclonic Activity ◽  
Max Planck ◽  
Pressure System ◽  
Wind Speeds ◽  
Average Lifespan ◽  
The North ◽  
The North Atlantic

<p>We analyse the connections between the wintertime North Atlantic Oscillation (NAO), the eddy-driven jet stream with the mid-latitude cyclonic activity over the North Atlantic and Europe. We investigate, through the comparison against ECMWF ERA5 and hindcast simulations from the Max Planck Institute Earth System Model (MPI-ESM), the potential for enhancement of the seasonal prediction skill of the Eddy Kinetic Energy (EKE) by accounting for the connections between large-scale climate and the regional cyclonic activity. Our analysis focuses on the wintertime months (December-March) in the 1979-2019 period, with seasonal predictions initialized every November 1st. We calculate EKE from wind speeds at 250 hPa, which we use as a proxy for cyclonic activity. The zonal and meridional wind speeds are bandpass filtered with a cut-off at 3-10 days to fit with the average lifespan of mid-latitude cyclones. </p><p>Preliminary results suggest that in ERA5, major positive anomalies in EKE, both in quantity and duration, are correlated with a northern position of the jet stream and a positive phase of the NAO. Apparently, a deepened Icelandic low-pressure system offers favourable conditions for mid-latitude cyclones in terms of growth and average lifespan. In contrast, negative anomalies in EKE over the North Atlantic and Central Europe are associated with a more equatorward jet stream, these are also linked to a negative phase of the NAO.  Thus, in ERA5, the eddy-driven jet stream and the NAO play a significant role in the spatial and temporal distribution of wintertime mid-latitude cyclonic activity over the North Atlantic and Europe. We extend this connection to the MPI-ESM hindcast simulations and present an analysis of their predictive skill of EKE for wintertime months.</p>

scholarly journals Patterns of millennial variability over the last 500 ka

2010 ◽  
Vol 6 (3) ◽  
pp. 295-303 ◽  
Author(s):  
M. Siddall ◽  
E. J. Rohling ◽  
T. Blunier ◽  
R. Spahni
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Glacial Cycles ◽  
The North ◽  
The North Atlantic ◽  
Paleoclimate Records ◽  
Temperature Proxy ◽  
Freshwater Release ◽  
Glacial Periods ◽  
Climate Events

Abstract. Millennial variability is a robust feature of many paleoclimate records, at least throughout the last several glacial cycles. Here we use the mean signal from Antarctic climate events 1 to 4 to probe the EPICA Dome C temperature proxy reconstruction through the last 500 ka for similar millennial-scale events. We find that clusters of millennial events occurred in a regular fashion over half of the time during this with a mean recurrence interval of 21 kyr. We find that there is no consistent link between ice-rafted debris deposition and millennial variability. Instead we speculate that changes in the zonality of atmospheric circulation over the North Atlantic form a viable alternative to freshwater release from icebergs as a trigger for millennial variability. We suggest that millennial changes in the zonality of atmospheric circulation over the North Atlantic are linked to precession via sea-ice feedbacks and that this relationship is modified by the presence of the large, Northern Hemisphere ice sheets during glacial periods.

scholarly journals Climate impacts on multidecadal <i>p</i>CO<sub>2</sub> variability in the North Atlantic: 1948–2009

2015 ◽  
Vol 12 (17) ◽  
pp. 15223-15244
Author(s):  
M. L. Breeden ◽  
G. A. McKinley
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Dissolved Inorganic Carbon ◽  
Atlantic Multidecadal Oscillation ◽  
Climate Impacts ◽  
Co2 Uptake ◽  
Subpolar Gyre ◽  
The North ◽  
The North Atlantic

Abstract. The North Atlantic is the most intense region of ocean CO2 uptake. Here, we investigate multidecadal timescale variability of the partial pressure CO2 (pCO2) that is due to the natural carbon cycle using a regional model forced with realistic climate and pre-industrial atmospheric pCO2 for 1948–2009. Large-scale patterns of natural pCO2 variability are primarily associated with basin-averaged sea surface temperature (SST) that, in turn, is composed of two parts: the Atlantic Multidecadal Oscillation (AMO) and a long-term positive SST trend. The North Atlantic Oscillation (NAO) drives a secondary mode of variability. For the primary mode, positive AMO and the SST trend modify pCO2 with different mechanisms and spatial patterns. Warming with the positive AMO increases subpolar gyre pCO2, but there is also a significant reduction of dissolved inorganic carbon (DIC) due primarily to reduced vertical mixing. The net impact of positive AMO is to reduce pCO2 in the subpolar gyre. Through direct impacts on SST, the net impacts of positive AMO is to increase pCO2 in the subtropical gyre. From 1980 to present, long-term SST warming has amplified AMO impacts on pCO2.

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