scholarly journals Reconstruction of Atlantic historical winter coastal storms in the Spanish coasts of the Gulf of Cadiz, 1929–2005

2011 ◽  
Vol 11 (6) ◽  
pp. 1715-1722 ◽  
Author(s):  
P. Ribera ◽  
D. Gallego ◽  
C. Pena-Ortiz ◽  
L. Del Rio ◽  
T. A. Plomaritis ◽  
...  
Keyword(s):  
Winter Season ◽  
Positive Trend ◽  
Gulf Of Cadiz ◽  
Atlantic Sector ◽  
Coastal Storms ◽  
The North ◽  
Gulf Of Cádiz ◽  
Instrumental Period ◽  
The North Atlantic Oscillation ◽  
The Impact

Abstract. This paper presents the reconstruction of a climatological series of winter coastal storms on the northern coasts of the Gulf of Cadiz. This series has been put together using information extracted from regional and local Spanish newspapers. It includes all the storms coming from the Atlantic sector that have been detected during the winter season, from October to March, between 1929 and 2005. In order to validate this historical storm series, it has been compared with storms series identified from quasi-observational data and using different wave heights as thresholds to decide what is to be considered as a coastal storm. Nearly 2.6 reports per year about coastal storms are published in the press which correspond to waves of 3.6 m high or more and to prevailing winds from a direction ranging between SSW and WNW. A long- term positive trend has been detected for the complete storm series. If only the instrumental period is analysed, no significant trend is detected. It is suggested that this difference might be associated with the impact of the North Atlantic Oscillation over the occurrence of storms in this area.

scholarly journals Reconciling North Atlantic climate modes: revised monthly indices for the East Atlantic and the Scandinavian patterns beyond the 20th century

2018 ◽  
Vol 10 (4) ◽  
pp. 2329-2344 ◽  
Author(s):  
Laia Comas-Bru ◽  
Armand Hernández
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Winter Season ◽  
East Atlantic ◽  
Atlantic Sector ◽  
The North ◽  
North Atlantic Climate ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
Different Sources

Abstract. Climate variability in the North Atlantic sector is commonly ascribed to the North Atlantic Oscillation. However, recent studies have shown that taking into account the second and third mode of variability (namely the East Atlantic – EA – and the Scandinavian – SCA – patterns) greatly improves our understanding of their controlling mechanisms, as well as their impact on climate. The most commonly used EA and SCA indices span the period from 1950 to present, which is too short, for example, to calibrate palaeoclimate records or assess their variability over multi-decadal scales. To tackle this, here, we create new EOF-based (empirical orthogonal function) monthly EA and SCA indices covering the period from 1851 to present, and compare them with their equivalent instrumental indices. We also review and discuss the value of these new records and provide insights into the reasons why different sources of data may give slightly different time series. Furthermore, we demonstrate that using these patterns to explain climate variability beyond the winter season needs to be done carefully due to their non-stationary behaviour. The datasets are available at https://doi.org/10.1594/PANGAEA.892769.

Spatial differences in the impact of the North Atlantic Oscillation on the flow of rivers in Europe

2011 ◽  
Vol 42 (1) ◽  
pp. 30-39 ◽  
Author(s):  
Dariusz Wrzesiński ◽  
Rafał Paluszkiewicz
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Winter Season ◽  
Winter Period ◽  
The North ◽  
The North Atlantic ◽  
Positive Correlations ◽  
The North Atlantic Oscillation ◽  
River Profiles ◽  
The Impact

The article presents regional differences in the impact that the North Atlantic Oscillation (NAO) exerts on the flow of European rivers. The impact is determined by temporal variations in the strength of relations expressed by coefficients of correlation between monthly or seasonal NAO indices and discharges recorded at 510 river profiles. The results of the correlation analysis were arranged using Ward’s method of hierarchical grouping. The classification of river profiles thus obtained made it possible to distinguish seven regions differing in the nature of the dependence between streamflow and the intensity of the NAO. The most statistically significant positive correlations are displayed by the rivers of Fennoscandia, Denmark and the northwest part of the British Isles in the winter period, while the most significant negative correlations (also in winter) are recorded for streams of the Mediterranean Basin, western France and the southeast of England. In the southeast part of the Baltic Sea drainage basin, significant positive correlations of streamflow with the NAO indices can be observed in the winter season and negative correlations are observed in spring.

scholarly journals Reconciling North Atlantic climate modes: Revised monthly indices for the East Atlantic and the Scandinavian patterns beyond the 20th century

2018 ◽  
Author(s):  
Laia Comas-Bru ◽  
Armand Hernández
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Winter Season ◽  
East Atlantic ◽  
Atlantic Sector ◽  
The North ◽  
North Atlantic Climate ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
Different Sources

Abstract. Climate variability in the North Atlantic sector is commonly ascribed to the North Atlantic Oscillation. However, recent studies have shown that taking into account the second and third mode of variability (namely the East Atlantic – EA – and the Scandinavian – SCA – patterns) greatly improves our understanding of their controlling mechanisms, as well as their impact on climate. The most commonly used EA and SCA indices span the period from 1950 to present which is too short, for example, to calibrate palaeoclimate records or assess their variability over multi-decadal scales. To tackle this, here, we create new EOF-based monthly EA and SCA indices covering the period from 1851 to present; and compare them with their equivalent instrumental indices. We also review and discuss the value of these new records and provide insights into the reasons why different sources of data may give slightly different time-series. Furthermore, we demonstrate that using these patterns to explain climate variability beyond the winter season needs to be done carefully due to their non-stationary behaviour. The datasets are available at https://doi.pangaea.de/10.1594/PANGAEA.892769.

scholarly journals Thrust–wrench interference tectonics in the Gulf of Cadiz (Africa–Iberia plate boundary in the North-East Atlantic): Insights from analog models

2011 ◽  
Vol 289 (1-4) ◽  
pp. 135-149 ◽  
Author(s):  
João C. Duarte ◽  
Filipe M. Rosas ◽  
Pedro Terrinha ◽  
Marc-André Gutscher ◽  
Jacques Malavieille ◽  
...  
Keyword(s):  
Plate Boundary ◽  
Gulf Of Cadiz ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
Gulf Of Cádiz ◽  
Analog Models

scholarly journals The Impact of the North Atlantic Oscillation on Climate through Its Influence on the Atlantic Meridional Overturning Circulation

2016 ◽  
Vol 29 (3) ◽  
pp. 941-962 ◽  
Author(s):  
Thomas L. Delworth ◽  
Fanrong Zeng
Keyword(s):  
North Atlantic ◽  
Time Scale ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
The North ◽  
Hemispheric Temperature ◽  
Meridional Overturning ◽  
The North Atlantic Oscillation ◽  
The Impact ◽  
Model Ocean

Abstract The impact of the North Atlantic Oscillation (NAO) on the Atlantic meridional overturning circulation (AMOC) and large-scale climate is assessed using simulations with three different climate models. Perturbation experiments are conducted in which a pattern of anomalous heat flux corresponding to the NAO is added to the model ocean. Differences between the perturbation experiments and a control illustrate how the model ocean and climate system respond to the NAO. A positive phase of the NAO strengthens the AMOC by extracting heat from the subpolar gyre, thereby increasing deep-water formation, horizontal density gradients, and the AMOC. The flux forcings have the spatial structure of the observed NAO, but the amplitude of the forcing varies in time with distinct periods varying from 2 to 100 yr. The response of the AMOC to NAO variations is small at short time scales but increases up to the dominant time scale of internal AMOC variability (20–30 yr for the models used). The amplitude of the AMOC response, as well as associated oceanic heat transport, is approximately constant as the time scale of the forcing is increased further. In contrast, the response of other properties, such as hemispheric temperature or Arctic sea ice, continues to increase as the time scale of the forcing becomes progressively longer. The larger response is associated with the time integral of the anomalous oceanic heat transport at longer time scales, combined with an increased impact of radiative feedback processes. It is shown that NAO fluctuations, similar in amplitude to those observed over the last century, can modulate hemispheric temperature by several tenths of a degree.

scholarly journals Impact of precipitation intermittency on NAO-temperature signals in proxy records

2013 ◽  
Vol 9 (2) ◽  
pp. 871-886 ◽  
Author(s):  
M. Casado ◽  
P. Ortega ◽  
V. Masson-Delmotte ◽  
C. Risi ◽  
D. Swingedouw ◽  
...  
Keyword(s):  
General Circulation ◽  
Ice Core ◽  
Circulation Model ◽  
Ice Cores ◽  
Stable Isotope Ratio ◽  
Global Network ◽  
Temporal Correlations ◽  
The North ◽  
The North Atlantic Oscillation ◽  
The Impact

Abstract. In mid and high latitudes, the stable isotope ratio in precipitation is driven by changes in temperature, which control atmospheric distillation. This relationship forms the basis for many continental paleoclimatic reconstructions using direct (e.g. ice cores) or indirect (e.g. tree ring cellulose, speleothem calcite) archives of past precipitation. However, the archiving process is inherently biased by intermittency of precipitation. Here, we use two sets of atmospheric reanalyses (NCEP (National Centers for Environmental Prediction) and ERA-interim) to quantify this precipitation intermittency bias, by comparing seasonal (winter and summer) temperatures estimated with and without precipitation weighting. We show that this bias reaches up to 10 °C and has large interannual variability. We then assess the impact of precipitation intermittency on the strength and stability of temporal correlations between seasonal temperatures and the North Atlantic Oscillation (NAO). Precipitation weighting reduces the correlation between winter NAO and temperature in some areas (e.g. Québec, South-East USA, East Greenland, East Siberia, Mediterranean sector) but does not alter the main patterns of correlation. The correlations between NAO, δ18O in precipitation, temperature and precipitation weighted temperature are investigated using outputs of an atmospheric general circulation model enabled with stable isotopes and nudged using reanalyses (LMDZiso (Laboratoire de Météorologie Dynamique Zoom)). In winter, LMDZiso shows similar correlation values between the NAO and both the precipitation weighted temperature and δ18O in precipitation, thus suggesting limited impacts of moisture origin. Correlations of comparable magnitude are obtained for the available observational evidence (GNIP (Global Network of Isotopes in Precipitation) and Greenland ice core data). Our findings support the use of archives of past δ18O for NAO reconstructions.

scholarly journals Dynamical analysis of a reduced model for the North Atlantic Oscillation

2021 ◽  
Author(s):  
Courtney Quinn ◽  
Dylan Harries ◽  
Terence J. O’Kane
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Growth Rates ◽  
Time Dependent ◽  
Unstable State ◽  
Time Step ◽  
Atlantic Sector ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

AbstractThe dynamics of the North Atlantic Oscillation (NAO) are analyzed through a data-driven model obtained from atmospheric reanalysis data. We apply a regularized vector autoregressive clustering technique to identify recurrent and persistent states of atmospheric circulation patterns in the North Atlantic sector (110°W-0°E, 20°N-90°N). In order to analyze the dynamics associated with the resulting cluster-based models, we define a time-dependent linear delayed map with a switching sequence set a priori by the cluster affiliations at each time step. Using a method for computing the covariant Lyapunov vectors (CLVs) over various time windows, we produce sets of mixed singular vectors (for short windows) and approximate the asymptotic CLVs (for longer windows). The growth rates and alignment of the resulting time-dependent vectors are then analyzed. We find that the window chosen to compute the vectors acts as a filter on the dynamics. For short windows, the alignment and changes in growth rates are indicative of individual transitions between persistent states. For long windows, we observe an emergent annual signal manifest in the alignment of the CLVs characteristic of the observed seasonality in the NAO index. Analysis of the average finite-time dimension reveals the NAO− as the most unstable state relative to the NAO+, with persistent AR states largely stable. Our results agree with other recent theoretical and empirical studies that have shown blocking events to have less predictability than periods of enhanced zonal flow.

scholarly journals Tidal and seasonal carbon and nutrients dynamics of the Guadalquivir Estuary and the Bay of Cádiz (SW Iberian Peninsula)

2012 ◽  
Vol 9 (10) ◽  
pp. 14537-14558
Author(s):  
M. Ribas-Ribas ◽  
L. I. Carracedo ◽  
E. Anfuso ◽  
J. M. Forja
Keyword(s):  
Continental Shelf ◽  
Dissolved Inorganic Carbon ◽  
Gulf Of Cadiz ◽  
Diurnal Variability ◽  
Guadalquivir Estuary ◽  
The North ◽  
Total Dissolved Nitrogen ◽  
Gulf Of Cádiz ◽  
Bay Of Cadiz ◽  
Bay Of Cádiz

Abstract. To study the effects of the physical environment on carbon and nutrients cycles dynamics in the north eastern shelf of the Gulf of Cádiz, changes in currents, tides, salinity, temperature, carbon system parameters (fugacity of CO2 (fCO2), dissolved organic carbon, dissolved inorganic carbon and pH) and others related (dissolved oxygen, total dissolved nitrogen, nutrients and suspended particulate matter) were measured in transects across the Guadalquivir Estuary and Bay of Cádiz mouths. Thus, the main objective of this study is to investigate the influence of these inner ecosystems on the carbon and nutrient distributions in the adjacent continental shelf. Three cruises have been undertaken in June 2006, November 2006 and February 2007, each one covering one complete tidal cycle during June, both systems were exporting components to the adjacent continental shelf of the Gulf of Cádiz. In an annual scale, Guadalquivir Estuary exported components while Bay of Cádiz imported them. Diurnal variability of fCO2 could have a potentially important implication on the estimate of air-sea CO2 fluxes. Monthly studies should be undertaken to completely understand this dynamic system.

scholarly journals Satellite-observed sea ice area flux through Baffin Bay: 1988–2015

2018 ◽  
Author(s):  
Haibo Bi ◽  
Yunhe Wang ◽  
Xiuli Xu ◽  
Yu Liang ◽  
Jue Huang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Vital Role ◽  
Positive Trend ◽  
Sea Ice Concentration ◽  
Baffin Bay ◽  
The North ◽  
Time Period ◽  
Sea Ice Drift ◽  
The North Atlantic Oscillation ◽  
Increasing Trends

Abstract. Sea ice export through Baffin Bay plays a vital role in modulating the meridional overturning process in the downstream Labrador Sea. In this study, satellite-derived sea ice products are explored to obtain the sea ice flux (SIF) through three passages (referred to as A, B, and C for the north, middle, and south passages, respectively) of Baffin Bay. Over the period 1988–2015, the average annual (October–September) sea ice area export is 555 × 103 km2, 642 × 103 km2, and 551 × 103 km2 through passages A, B, and C, respectively. These amounts are less than that observed through the Fram Strait (FS, 707 × 103 km2). Clear increasing trends in annual sea ice export on the order of 53.1 × 103 km2/de and 43.2 × 103 km2/de are identified at passages A and B, respectively. The trend at the south passage (C), however, is slightly negative (−13.3 × 103 km2/de). The positive trends in annual SIF at A and B are primarily attributable to the increase during winter months, which is triggered by the accelerated sea ice motion (SIM) and partly compensated by the reduced sea ice concentration (SIC). During the summer months, the sea ice export through each Baffin Bay passage usually presents a negative trend, primarily because of the decline in SIM and it is further enhanced by a dramatic decrease in SIC. A significant positive trend in the net SIF (i.e. net ice inflow) is found for between the passages A (or B) and C at 54.5 (or 64.2) × 103 km2/de. Therefore, Baffin Bay may have presented a greater convergence of ice. Overall, the connection between Baffin Bay sea ice export and the North Atlantic Oscillation (NAO) is tenuous, although the correlation is sensitive to variations in the selected time period. In contrast, the association with the cross-gate sea level pressure difference (SLPD) is robust in Baffin Bay (R = 0.69–0.71 depending on the passages), but relatively weaker compared with that in the FS (R = 0.74). Baffin Bay is bounded by Baffin Island to the west and Greenland to the east, thus, sea ice drift is not converted to the free state observed in the FS.

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