Assessing the influence of the North Atlantic Oscillation on a migratory demersal predator in the Alboran Sea

2015 ◽  
Vol 96 (7) ◽  
pp. 1499-1505 ◽  
Author(s):  
José Carlos Báez
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Large Scale ◽  
Regime Shift ◽  
Close Association ◽  
Alboran Sea ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
Alborán Sea

This study analysed the regime shift of tope shark and the overlapping taxa Raja spp. in the Alboran Sea. Tope shark and Raja spp. landings are both significantly correlated with the North Atlantic Oscillation (NAO). A significant negative correlation was found between Raja spp. landings and tope shark landings. This finding suggests that climatic oscillations affect regime shifts between these taxa in the Alboran Sea. Studies are scarce on the dependence of deep-sea communities on biological and physical processes occurring in near-shore pelagic environments mediated by large-scale atmospheric phenomena. Similar to previous studies on the Mediterranean Sea, a close association was found between landings of deep-water animals and the NAO. The main conclusion is that the regime shift of tope shark and the overlapping taxa Raja spp. is mediated by a negative NAO and accumulated snow.

scholarly journals The North Atlantic Oscillation Response to Large-Scale Atmospheric Anomalies in the Northeastern Pacific

2013 ◽  
Vol 70 (9) ◽  
pp. 2854-2874 ◽  
Author(s):  
Marie Drouard ◽  
Gwendal Rivière ◽  
Philippe Arbogast
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Wave Breaking ◽  
Large Scale ◽  
Wave Train ◽  
Low Frequency ◽  
The North ◽  
Northeastern Pacific ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract Ingredients in the North Pacific flow influencing Rossby wave breakings in the North Atlantic and the intraseasonal variations of the North Atlantic Oscillation (NAO) are investigated using both reanalysis data and a three-level quasigeostrophic model on the sphere. First, a long-term run is shown to reproduce the observed relationship between the nature of the synoptic wave breaking and the phase of the NAO. Furthermore, a large-scale, low-frequency ridge anomaly is identified in the northeastern Pacific in the days prior to the maximum of the positive NAO phase both in the reanalysis and in the model. A large-scale northeastern Pacific trough anomaly is observed during the negative NAO phase but does not systematically precede it. Then, short-term linear and nonlinear simulations are performed to understand how the large-scale ridge anomaly can act as a precursor of the positive NAO phase. The numerical setup allows for analysis of the propagation of synoptic waves in the eastern Pacific in the presence of a large-scale ridge or trough anomaly and their downstream impact onto the Atlantic jet when they break. The ridge acts in two ways. First, it tends to prevent the downstream propagation of small waves compared to long waves. Second, it deflects the propagation of the wave trains in such a way that they mainly propagate equatorward in the Atlantic. The two modes of action favor the anticyclonic wave breaking and, therefore, the positive NAO phase. With the trough, the wave train propagation is more zonal, disturbances are more meridionally elongated, and cyclonic wave breaking is more frequent in the Atlantic than in the ridge case.

scholarly journals Stochastic Forcing of Ocean Variability by the North Atlantic Oscillation

2009 ◽  
Vol 39 (1) ◽  
pp. 162-184 ◽  
Author(s):  
Kettyah C. Chhak ◽  
Andrew M. Moore ◽  
Ralph F. Milliff
Keyword(s):  
North Atlantic Oscillation ◽  
Ocean Circulation ◽  
Rossby Wave ◽  
North Atlantic ◽  
Large Scale ◽  
Western Boundary ◽  
Stochastic Forcing ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract At middle and high latitudes, the magnitude of stochastic wind stress forcing of the ocean by atmospheric variability on synoptic time scales (i.e., “weather” related variability) is comparable to that of the seasonal cycle. Stochastic forcing may therefore have a significant influence on the ocean circulation, climate, and ocean predictability. Here, the influence of stochastic forcing associated with the North Atlantic Oscillation on the subtropical gyre circulation of the North Atlantic is explored in an eddy-permitting quasigeostrophic framework. For the North Atlantic winds used in this study, the root-mean-square of the annual average Ekman pumping velocity of the seasonal cycle between 35° and 52°N is 1.3 × 10−7 m s−1, while the wintertime standard deviation of the stochastic component of the North Atlantic Oscillation over the same latitude band is 2.2 × 10−7 m s−1. Significant stochastically induced variability in the ocean circulation occurs near the western boundary region and along the western margins of the abyssal plains associated with vortex stretching, energy release from the mean flow, and the generation of topographic Rossby waves. Variability arises from a combination of two effects, depending on the measure of variance used: growth of unstable modes of the underlying circulation and modal interference resulting from their nonnormal nature, which dominates during the first 10 days or so of perturbation growth. Near the surface, most of the variability is associated with large-scale changes in the barotropic circulation, although more than 20% of the energy and enstrophy variability is associated with small-scale baroclinic waves. In the deep ocean, much of the stochastically induced variability is apparently due to topographic Rossby wave activity along the continental rise and ocean ridges. Previous studies have demonstrated that rectification of topographic Rossby wave–induced circulations in the western North Atlantic may contribute to the western boundary current recirculation zones. The authors suggest that a source of topographic Rossby wave energy, significant enough to rectify the mean ocean circulation, may arise from stochastic forcing by large-scale atmospheric forcing, such as the North Atlantic Oscillation and other atmospheric teleconnection patterns.

Weather Regime Transitions and the Interannual Variability of the North Atlantic Oscillation. Part II: Dynamical Processes

2012 ◽  
Vol 69 (8) ◽  
pp. 2347-2363 ◽  
Author(s):  
Dehai Luo ◽  
Jing Cha ◽  
Steven B. Feldstein
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Large Scale ◽  
Storm Track ◽  
Constructive Interference ◽  
Dynamical Processes ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
Regime Transitions

Abstract In this study, attention is focused on identifying the dynamical processes that contribute to the negative North Atlantic Oscillation (NAO)− to positive NAO (NAO+) and NAO+ to NAO− transitions that occur during 1978–90 (P1) and 1991–2008 (P2). By constructing Atlantic ridge (AR) and Scandinavian blocking (SBL) indices, the composite analysis demonstrates that in a stronger AR (SBL) winter NAO− (NAO+) event can more easily transition into an NAO+ (NAO−) event. Composites of 300-hPa geopotential height anomalies for the NAO− to NAO+ and NAO+ to NAO− transition events during P1 and P2 are calculated. It is shown for P2 (P1) that the NAO+ to SBL to NAO− (NAO− to AR to NAO+) transition results from the retrograde drift of an enhanced high-latitude, large-scale, positive (negative) anomaly over northern Europe during the decay of the previous NAO+ (NAO−) event. This finding cannot be detected for NAO events without transition. Moreover, it is found that the amplification of retrograding wavenumber 1 is more important for the NAO− to NAO+ transition during P1, but the marked reintensification and retrograde movement of both wavenumbers 1 and 2 after the NAO+ event decays is crucial for the NAO+ to NAO− transition during P2. It is further shown that destructive (constructive) interference between wavenumbers 1 and 2 over the North Atlantic during P1 (P2) is responsible for the subsequent weak NAO+ (strong NAO−) anomaly associated with the NAO− to NAO+ (NAO+ to NAO−) transition. Also, the weakening (strengthening) of the vertically integrated zonal wind (upstream Atlantic storm track) is found to play an important role in the NAO regime transition.

On the Resonances and Teleconnections of the North Atlantic and Madden-Julian Oscillations

2020 ◽  
Author(s):  
Gilbert Brunet ◽  
Yosvany Martinez ◽  
Hai Lin ◽  
Natacha Bernier
Keyword(s):  
North Atlantic Oscillation ◽  
Normal Mode ◽  
North Atlantic ◽  
Large Scale ◽  
Normal Mode Analysis ◽  
Mode Analysis ◽  
Dynamic Framework ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

<p>The key to better prediction of S2S variability and weather regimes in a changing climate lies with improved understanding of the fundamental nature of S2S phase space structure and associated predictability and dynamical processes. The latter can be decomposed into a finite number of relatively large-scale discrete-like Rossby waves with coherent space-time characteristics using Empirical Normal Mode (ENM) analysis. ENM analysis is based on principal component analysis, conservation laws and normal mode theories. These modes evolve in a complex manner through nonlinear interactions with themselves and transient eddies and weak dissipative processes. Within this atmospheric dynamic framework, we will discuss the teleconnections and the 35-day wave resonance of the North Atlantic Oscillation using recent diagnostics and numerical experiments.</p><p>References</p><p>Brunet, G. and J. Methven, 2018: Identifying wave processes associated with predictability across time scales: An empirical normal mode approach. Book chapter in Sub-seasonal to seasonal prediction: The gap between weather and climate forecasting. Editors A.W. Robertson and F. Vitart, Elsevier. p.1-42</p><p>Brunet, G. 1994:  Empirical normal mode analysis of atmospheric data. J. Atmos. Sci., 51, 932-952.</p><p>Lin, H., G. Brunet, and J. Derome, 2009: An observed connection between the North Atlantic Oscillation and the Madden-Julian Oscillation.  J. Climate, 22, 364-380.</p><p>Lin, H., G. Brunet and J. Derome 2007: Intraseasonal Variability in a Dry Atmospheric Model, J. Atmos. Sci., 64, 2442-2441.</p>

scholarly journals Effect of large-scale modes of total variability of the atmosphere and ocean in the Atlantic-European region on the climate of Belarus

2020 ◽  
Vol 64 (5) ◽  
pp. 609-616
Author(s):  
S. A. Lysenko ◽  
V. F. Loginov ◽  
I. V. Buyakov
Keyword(s):  
North Atlantic Oscillation ◽  
Air Temperature ◽  
North Atlantic ◽  
Large Scale ◽  
European Region ◽  
The North ◽  
Temperature And Precipitation ◽  
Acceleration And Deceleration ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

We have established the relationships of quasicyclic components in changes of air temperature and precipitation in Belarus with large-scale modes of general variability of the atmosphere and ocean in the Atlantic-European region. When the summer air temperature changes in Belarus and in Eastern Europe, a quasi-60-year oscillation is identified, which coincides in phase with the Atlantic multi-decadal oscillation. It is shown that the time series of winter air temperature in Belarus contain a quasi-8-year component synchronized with a similar component of the North Atlantic Oscillation. Moreover, the periods of acceleration and deceleration of winter warming in Belarus coincide with the upward and downward quasi-30-year phases of the North Atlantic Oscillation, respectively. The latter are also consistent with fluctuations in moisture content in Belarus and Europe. Based on the established patterns, we have concluded that the rapid rise in winter temperatures, slowing down of summer warming and deterioration in water supply in the southern regions of Belarus observed in the last decade are part of a natural cycle lasting about 30 years, developing against the background of a long-term trend of anthropogenic global warming. 

scholarly journals Impact of the North Atlantic Oscillation on the variations of aerosol ground levels through local processes over Europe

2013 ◽  
Vol 13 (5) ◽  
pp. 13889-13914 ◽  
Author(s):  
S. Jerez ◽  
P. Jimenez-Guerrero ◽  
J. P. Montávez ◽  
R. M. Trigo
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Large Scale ◽  
Ground Level ◽  
Oxidative Capacity ◽  
Radiation Balance ◽  
Potential Predictability ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. This contribution assesses non-antropogenic variations in ground-level aerosol concentrations over Europe associated to changes in the phase of the North Atlantic Oscillation (NAO). The NAO controls a large amount of the European climate variability with asymmetric impacts in both time and space. Based on simulated data and focusing on how the local atmospheric processes (without considering large-scale mechanisms) governed by the NAO affect the levels of various aerosol species, this study highlights that positive NAO phases favor increased aerosols levels in southern (northern) regions in winter (summer), while negative NAO phases enhance them in northern (southern) regions in winter (summer). Variations are up to and over 100% for most aerosols, being clearly related to the NAO-impact on precipitation and wind, as they act to clean the atmosphere through removal and dispersion processes, and to the NAO-impact on the radiation balance (i.e. cloudiness) as it rebounds on the biogenic emitting activity and on the oxidative capacity of the atmosphere. Beyond deepening on the understanding of fundamental interactions between climate and air quality, these results provide a basis for improving the potential predictability of this later since much work is being done in order to gain accuracy in the NAO predictions.

scholarly journals Wave Energy Extraction by the End of the Century: Impact of the North Atlantic Oscillation

2018 ◽  
Author(s):  
Jelena Janjić ◽  
Sarah Gallagher ◽  
Emily Gleeson ◽  
Frédéric Dias
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Large Scale ◽  
Global Climate ◽  
Wave Climate ◽  
Wavewatch Iii ◽  
The North ◽  
Wave Parameters ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Using wind speeds and sea ice fields from the EC-Earth global climate model to run the WAVEWATCH III model, we investigate the changes in the wave climate of the northeast Atlantic by the end of the 21st century. Changes in wave climate parameters are related to changes in wind forcing both locally and remotely. In particular, we are interested in the behavior of large-scale atmospheric oscillations and their influence on the wave climate of the North Atlantic Ocean. Knowing that the North Atlantic Oscillation (NAO) is related to large-scale atmospheric circulation, we carried out a correlation analysis of the NAO pattern using an ensemble of EC-Earth global climate simulations. These simulations include historical periods (1980–2009) and projected changes (2070–2099) by the end of the century under the RCP4.5 and RCP8.5 Representative Concentration Pathway (RCP) forcing scenarios with three members in each RCP wave model ensemble. In addition, we analysed the correlations between the NAO and a range of wave parameters that describe the wave climate from EC-Earth driven WAVEWATCH III model simulation over the North Atlantic basin, focusing on a high resolution two-way nested grid over the northeast Atlantic. The results show a distinct decrease by the end of the century and a strong positive correlation with the NAO for all wave parameters observed.

scholarly journals Spatiotemporal variability of lightning activity in Europe and the relation to the North Atlantic Oscillation teleconnection pattern

2017 ◽  
Vol 17 (8) ◽  
pp. 1319-1336 ◽  
Author(s):  
David Piper ◽  
Michael Kunz
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Large Scale ◽  
Lightning Activity ◽  
Spatiotemporal Variability ◽  
Convective Activity ◽  
Diurnal Cycles ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. Comprehensive lightning statistics are presented for a large, contiguous domain covering several European countries such as France, Germany, Austria, and Switzerland. Spatiotemporal variability of convective activity is investigated based on a 14-year time series (2001–2014) of lightning data. Based on the binary variable thunderstorm day, the mean spatial patterns of lightning activity and regional peculiarities regarding seasonality are discussed. Diurnal cycles are compared among several regions and evaluated with respect to major seasonal changes. Further analyses are performed regarding interannual variability and the impact of teleconnection patterns on convection. Mean convective activity across central Europe is characterized by a strong northwest-to-southeast gradient with pronounced secondary features superimposed. The zone of maximum values of thunderstorm days propagates southwestward along the southern Alpine range from April to July. Diurnal cycles vary substantially between both different months and regions, particularly regarding the incidence of nighttime lightning. The North Atlantic Oscillation (NAO) is shown to have a significant impact on convective activity in several regions, which is primarily caused by variations of the large-scale lifting pattern in both NAO phases. This dynamical effect is partly compensated for by thermodynamical modifications of the pre-convective environment. The results point to a crucial role of large-scale flow in steering the spatiotemporal patterns of convective activity.

Malthus and the North Atlantic Oscillation: A Reply to Kyle Harper

2016 ◽  
Vol 46 (4) ◽  
pp. 563-578
Author(s):  
John L. Brooke
Keyword(s):  
Climate Change ◽  
North Atlantic Oscillation ◽  
Central Asia ◽  
North Atlantic ◽  
Large Scale ◽  
Classical Antiquity ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The Impact

Subsequent to Harper’s review essay centered on Brooke’s Climate Change and the Course of Global History: A Rough Journey, Brooke concedes that he could have focused more attention on the problem of the Malthusian trap. He stresses, nevertheless, that his reservations regarding the concept of Malthusian crises in pre-industrial societies are well placed, given the concept’s prominence in the large-scale environmental histories written during the past several decades. Turning to the impact of climate change in late classical antiquity, Brooke discusses established and new evidence for increasing, sometimes catastrophic, precipitation from the Mediterranean area into central Asia after a.d. 500 and after 1250, as a result of shifts toward the negative mode of the North Atlantic Oscillation. He also surveys the evidence for emerging arguments that this cooling-driven precipitation may have triggered outbreaks of bubonic plague in Central Asia.

scholarly journals The Arctic Winter Sea Ice Quadrupole Revisited

2017 ◽  
Vol 30 (9) ◽  
pp. 3157-3167 ◽  
Author(s):  
S. Close ◽  
M.-N. Houssais ◽  
C. Herbaut
Keyword(s):  
Sea Ice ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Large Scale ◽  
Dominant Mode ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

The dominant mode of Arctic sea ice variability in winter is often maintained to be represented by a quadrupole structure, comprising poles of one sign in the Okhotsk, Greenland, and Barents Seas and of opposing sign in the Labrador and Bering Seas, forced by the North Atlantic Oscillation. This study revisits this large-scale winter mode of sea ice variability using microwave satellite and reanalysis data. It is found that the quadrupole structure does not describe a significant covariance relationship among all four component poles. The first empirical orthogonal mode, explaining covariability in the sea ice of the Barents, Greenland, and Okhotsk Seas, is linked to the Siberian high, while the North Atlantic Oscillation only exhibits a significant relationship with the Labrador Sea ice, which varies independently as the second mode. The principal components are characterized by a strong low-frequency signal; because the satellite record is still short, these results suggest that statistical analyses should be applied cautiously.

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