scholarly journals The Sub-Polar Gyre Index – a community data set for application in fisheries and environment research

2016 ◽  
Author(s):  
Barbara Berx ◽  
Mark R. Payne
Keyword(s):  
Time Series ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Marine Ecosystem ◽  
Series Length ◽  
Data Set ◽  
The North ◽  
Community Data ◽  
Definition Of ◽  
Index Time Series

Abstract. Scientific interest in the sub-polar gyre of the North Atlantic Ocean has increased in recent years. The sub-polar gyre has contracted and weakened, and changes in circulation pathways have been linked to changes in marine ecosystem productivity. To aid fisheries and environmental scientists, we here present a time series of the Sub-Polar Gyre Index (SPG-I) based on monthly mean maps of sea surface height. The established definition of the SPG-I is applied, and the first EOF and PC are presented. Sensitivity to the spatial domain and time series length are explored, but found not to be important factors. Our time series compares well with indices presented previously. The SPG-I time series is freely available online (doi:10.7489/1806-1) and we invite the community to access, apply and publish studies using this index time series.

scholarly journals The Sub-Polar Gyre Index – a community data set for application in fisheries and environment research

2017 ◽  
Vol 9 (1) ◽  
pp. 259-266 ◽  
Author(s):  
Barbara Berx ◽  
Mark R. Payne
Keyword(s):  
Time Series ◽  
North Atlantic Ocean ◽  
Marine Ecosystem ◽  
Principal Component ◽  
Series Length ◽  
Data Set ◽  
The North ◽  
Community Data ◽  
Definition Of ◽  
Index Time Series

Abstract. Scientific interest in the sub-polar gyre of the North Atlantic Ocean has increased in recent years. The sub-polar gyre has contracted and weakened, and changes in circulation pathways have been linked to changes in marine ecosystem productivity. To aid fisheries and environmental scientists, we present here a time series of the Sub-Polar Gyre Index (SPG-I) based on monthly mean maps of sea surface height. The established definition of the SPG-I is applied, and the first EOF (empirical orthogonal function) and PC (principal component) are presented. Sensitivity to the spatial domain and time series length are explored but found not to be important factors in terms of the SPG-I's interpretation. Our time series compares well with indices presented previously. The SPG-I time series is freely available online (http://dx.doi.org/10.7489/1806-1), and we invite the community to access, apply, and publish studies using this index time series.

scholarly journals Detecting quasi-oscillations in the monthly precipitation regimes of the Iberian Peninsula

2003 ◽  
Vol 21 (3) ◽  
pp. 819-832 ◽  
Author(s):  
L. Morala ◽  
A. Serrano ◽  
J. A. Garcia
Keyword(s):  
Time Series ◽  
High Pressure ◽  
Iberian Peninsula ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Singular Spectrum Analysis ◽  
Monthly Precipitation ◽  
The North ◽  
Precipitation Regimes ◽  
The North Atlantic

Abstract. A spectral analysis of the time series corresponding to the main monthly precipitation regimes of the Iberian Peninsula was performed using two methods, the Multi-Taper Method and Monte Carlo Singular Spectrum Analysis. The Multi-Taper Method gave a preliminary view of the presence of signals in some of the time series. Monte Carlo Singular Spectrum Analysis discriminated between potential oscillations and noise. From the results of the two methods it is concluded that there exist three significant quasi-oscillations at the 95% level of confidence: a 5.0 year quasi-oscillation and a long-term trend in the Atlantic pattern of March, a 3.2 year quasi-oscillation in the Cantabrian pattern of January, and a 4.0 year quasi-oscillation in the Catalonian pattern of February. These quasi-oscillations might be related to climatic variations with similar periodicities over the North Atlantic Ocean. The possible simultaneity of high values of precipitation generated by the significant quasi-oscillations and high sea–level pressures was studied by means of composite maps. It was found that high values of precipitation generated by the oscillations of the Atlantic patterns of January and March exist simultaneously with a specific high pressure structure over the North Atlantic Ocean, that allow cyclonic perturbations to cross the Iberian Peninsula. During the non-wet years, this high pressure structure moves northwards, keeping the track of the low pressure centers to the north, far from the Iberian Peninsula. On the other hand, high values of precipitation generated by the oscillation of the Cantabrian pattern of January exist simultaneously with a high pressure structure over the Galicia region and the Cantabrian Sea, that allow a northerly flow over the region. Also, a positive trend in the NAO index for March has been found, starting in the sixties, which is not evident for other winter months. This trend agrees with the decreasing trend found in the March Atlantic pattern.Key words. Meteorology and atmospheric dynamics (climatology; precipitation) Oceanography: general (climate and interannual variability)

scholarly journals Prevalence of the Chloroflexi-Related SAR202 Bacterioplankton Cluster throughout the Mesopelagic Zone and Deep Ocean

2004 ◽  
Vol 70 (5) ◽  
pp. 2836-2842 ◽  
Author(s):  
R. M. Morris ◽  
M. S. Rappé ◽  
E. Urbach ◽  
S. A. Connon ◽  
S. J. Giovannoni
Keyword(s):  
Time Series ◽  
Pacific Ocean ◽  
16S Rrna ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
The North ◽  
The North Atlantic

ABSTRACT Since their initial discovery in samples from the north Atlantic Ocean, 16S rRNA genes related to the environmental gene clone cluster known as SAR202 have been recovered from pelagic freshwater, marine sediment, soil, and deep subsurface terrestrial environments. Together, these clones form a major, monophyletic subgroup of the phylum Chloroflexi. While members of this diverse group are consistently identified in the marine environment, there are currently no cultured representatives, and very little is known about their distribution or abundance in the world's oceans. In this study, published and newly identified SAR202-related 16S rRNA gene sequences were used to further resolve the phylogeny of this cluster and to design taxon-specific oligonucleotide probes for fluorescence in situ hybridization. Direct cell counts from the Bermuda Atlantic time series study site in the north Atlantic Ocean, the Hawaii ocean time series site in the central Pacific Ocean, and along the Newport hydroline in eastern Pacific coastal waters showed that SAR202 cluster cells were most abundant below the deep chlorophyll maximum and that they persisted to 3,600 m in the Atlantic Ocean and to 4,000 m in the Pacific Ocean, the deepest samples used in this study. On average, members of the SAR202 group accounted for 10.2% (±5.7%) of all DNA-containing bacterioplankton between 500 and 4,000 m.

scholarly journals The North Atlantic Oscillations: Cycle Times for the NAO, the AMO and the AMOC

Climate ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 43 ◽  
Author(s):  
Knut Lehre Seip ◽  
Øyvind Grøn ◽  
Hui Wang
Keyword(s):  
Time Series ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Atlantic Multidecadal Oscillation ◽  
Meridional Overturning Circulation ◽  
Cycle Times ◽  
The North ◽  
In Series ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

We show that oceanic cycle lengths persist across oceanic cyclic time-series by comparing cycles in series that come from “sister” measurements in the North Atlantic Ocean. These are the North Atlantic oscillation (NAO), the Atlantic multidecadal oscillation (AMO) and the Atlantic meridional overturning circulation (AMOC). The raw NAO series, which is an extremely noisy series in its raw format, showed cycles at 7, 13, 20, 26 and 34 years that were common with, or overlapped, the other two series, and across increasing degrees of smoothing of the NAO series. At the 1960 midpoint of the hiatus period 1943–1975, NAO was leading time-series to AMOC and AMO and AMO was a leading time-series to AMOC, but in 1975, at the end of the hiatus period, the leading relations were reversed.

scholarly journals C : N : P stoichiometry at the Bermuda Atlantic Time-series Study station in the North Atlantic Ocean

2015 ◽  
Vol 12 (12) ◽  
pp. 9275-9305
Author(s):  
A. Singh ◽  
S. E. Baer ◽  
U. Riebesell ◽  
A. C. Martiny ◽  
M. W. Lomas
Keyword(s):  
Time Series ◽  
Organic Matter ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Euphotic Zone ◽  
Redfield Ratio ◽  
The North ◽  
Elemental Stoichiometry ◽  
Series Study

Abstract. Nitrogen (N) and phosphorus (P) availability determine the strength of the ocean's carbon (C) uptake, and variation in the N : P ratio in inorganic nutrients is key to phytoplankton growth. A similarity between C : N : P ratios in the plankton biomass and deep-water nutrients was observed by Alfred C. Redfield around 80 years ago and suggested that biological processes in the surface ocean controlled deep ocean chemistry. Recent studies have emphasized the role of inorganic N : P ratios in governing biogeochemical processes, particularly the C : N : P ratio in suspended particulate organic matter (POM), with somewhat less attention given to exported POM and dissolved organic matter (DOM). Herein, we extend the discussion on ecosystem C : N : P stoichiometry but also examine temporal variation of stoichiometric relationships. We have analysed elemental stoichiometry in the suspended POM and total (POM + DOM) organic matter (TOM) pools in the upper 100 m, and in the exported POM and sub-euphotic zone (100–500 m) inorganic nutrient pools from the monthly data collected at the Bermuda Atlantic Time-series Study (BATS) site located in the western part of the North Atlantic Ocean. C : N : P ratios in the TOM pool were more than twice that in the POM pool. Observed C : N ratios in suspended POM were approximately equal to the canonical Redfield Ratio (C : N : P = 106 : 16 : 1), while N : P and C : P ratios in the same pool were more than twice the Redfield Ratio. Average N : P ratios in the subsurface inorganic nutrient pool were ~ 26 : 1, squarely between the suspended POM ratio and the Redfield ratio. We have further linked variation in elemental stoichiometry with that of phytoplankton cell abundance observed at the BATS site. Findings from this study suggest that the variation elemental ratios with depth in the euphotic zone was mainly due to different growth rates of cyanobacterial cells. These time-series data have also allowed us to examine the potential role of climate variability on C : N : P stoichiometry. This study strengthens our understanding of elemental stoichiometry in different organic matter pools and should improve biogeochemical models by constraining the range of non-Redfield stoichiometry.

scholarly journals Mercury distribution and transport in the North Atlantic Ocean along the GEOTRACES-GA01 transect

2018 ◽  
Vol 15 (8) ◽  
pp. 2309-2323 ◽  
Author(s):  
Daniel Cossa ◽  
Lars-Eric Heimbürger ◽  
Fiz F. Pérez ◽  
Maribel I. García-Ibáñez ◽  
Jeroen E. Sonke ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Geometric Mean ◽  
Meridional Overturning Circulation ◽  
Labrador Sea ◽  
Subpolar Gyre ◽  
Data Set ◽  
The North ◽  
The North Atlantic

Abstract. We report here the results of total mercury (HgT) determinations along the 2014 Geotraces Geovide cruise (GA01 transect) in the North Atlantic Ocean (NA) from Lisbon (Portugal) to the coast of Labrador (Canada). HgT concentrations in unfiltered samples (HgTUNF) were log-normally distributed and ranged between 0.16 and 1.54 pmol L−1, with a geometric mean of 0.51 pmol L−1 for the 535 samples analysed. The dissolved fraction (< 0.45 µm) of HgT (HgTF), determined on 141 samples, averaged 78 % of the HgTUNF for the entire data set, 84 % for open seawaters (below 100 m) and 91 % if the Labrador Sea data are excluded, where the primary production was high (with a winter convection down to 1400 m). HgTUNF concentrations increased eastwards and with depth from Greenland to Europe and from subsurface to bottom waters. The HgTUNF concentrations were similarly low in the subpolar gyre waters ( ∼  0.45 pmol L−1), whereas they exceeded 0.60 pmol L−1 in the subtropical gyre waters. The HgTUNF distribution mirrored that of dissolved oxygen concentration, with highest concentration levels associated with oxygen-depleted zones. The relationship between HgTF and the apparent oxygen utilization confirms the nutrient-like behaviour of Hg in the NA. An extended optimum multiparameter analysis allowed us to characterize HgTUNF concentrations in the different source water types (SWTs) present along the transect. The distribution pattern of HgTUNF, modelled by the mixing of SWTs, show Hg enrichment in Mediterranean waters and North East Atlantic Deep Water and low concentrations in young waters formed in the subpolar gyre and Nordic seas. The change in anthropogenic Hg concentrations in the Labrador Sea Water during its eastward journey suggests a continuous decrease in Hg content in this water mass over the last decades. Calculation of the water transport driven by the Atlantic Meridional Overturning Circulation across the Portugal–Greenland transect indicates northward Hg transport within the upper limb and southward Hg transport within the lower limb, with resulting net northward transport of about 97.2 kmol yr−1.

scholarly journals Modal composition of the central water in the North Atlantic subtropical gyre

2009 ◽  
Vol 6 (3) ◽  
pp. 2487-2506 ◽  
Author(s):  
A. Cianca ◽  
R. Santana ◽  
J. P. Marrero ◽  
M. J. Rueda ◽  
O. Llinás
Keyword(s):  
Time Series ◽  
North Atlantic ◽  
World Ocean ◽  
Average Density ◽  
Subtropical Gyre ◽  
Mode Water ◽  
Data Set ◽  
Modal Composition ◽  
The North ◽  
The North Atlantic

Abstract. The modal composition of the Central Water in the North Atlantic subtropical gyre is not clearly defined, as there are some uncertainties related to mode identification, as well as modes which are not well documented. This study shows that eastern North Atlantic Central Water (eastern NACW) in the subtropical gyre is composed of three modes: The North Atlantic Subpolar Mode Water (NASPMW σt=27.1 to 27.3), the Madeira Mode Water (MMW σt=26.4 to 26.6), and the mode water with a σt near 27.0, which is currently not well documented. We confirmed this mode based on the similarities found between it and the mode waters already reported. The similarities were determined from comparative analyses of the temperature/salinity standard curves and the gradients of the potential density anomalies of two concurrent data sets from two subtropical time-series stations (Bermuda Atlantic Time-series Study, BATS, in the west, and European Station for Time-series in the Ocean Canary Islands, ESTOC, in the east). In order to establish the outcropping regions, the corresponding pycnostads were determined using another climatologic data set (World Ocean Database, WOD2005). In this case, the pycnostads were located based on the presence of standard deviation minima from the average density anomalies. Finally, we confirmed that the pycnostads corresponded to the temperature values related to the modes by overlaying the characteristic modal isotherm of each of the modes in the geographic distribution of the pycnostads. Sea surface temperature data (SST) from the Ocean Pathfinder Program (OPP) were used to estimate the isotherms. The results showed a clear correspondence between the modal isotherms and the pycnostads, for both the modes that have already been documented and the mode confirmed in this study.

The circulation near the Reykjanes Ridge in summers 2015, 2016 and 2017

2021 ◽  
Author(s):  
Ivane Salaün ◽  
Virginie Thierry ◽  
Herlé Mercier
Keyword(s):  
North Atlantic ◽  
Water Mass ◽  
North Atlantic Ocean ◽  
Subpolar Gyre ◽  
Mode Water ◽  
Data Set ◽  
Reykjanes Ridge ◽  
Lower Mode ◽  
The North ◽  
The North Atlantic

&lt;p&gt;Located south of Iceland, the Reykjanes Ridge is a major topographic structure of the North Atlantic Ocean that strongly influences the spatial distribution and circulation of the North Atlantic Subpolar Gyre water masses. Around the ridge, the circulation is composed of two main along-ridge currents, the southwestward East Reykjanes Ridge Current (ERRC) in the Iceland Basin and the northeastward Irminger Current (IC) in the Irminger Sea. To study the along Reykjanes Ridge flow variability and the inter-basin connection through the ridge and connections with the interior of each basin, volume and water mass transports over the Reykjanes Ridge during summer 2015, 2016 and 2017 are analyzed. Data used are velocity and hydrographic measurements carried out along and perpendicular to the crest of the Reykjanes Ridge during the RREX (Reykjanes Ridge Experiment Project) cruises in June&amp;#8211;July 2015 and June&amp;#8211;July 2017 and BOCATS cruise in July 2016. The new circulation scheme in the area described in 2015&amp;#160; by Petit et al. (J. Geophys. Res., 2018) with flows connecting the ERRC and IC branches at specific locations set by the bathymetry of the ridge is again observed&amp;#160; in 2016 and&amp;#160; 2017, with variations concerning the connections with the interiors of the basins. The data set reveals remarkable changes in the hydrological properties and transports of the ERRC, IC and cross ridge flows. The westward transport across the ridge, which represents the subpolar gyre intensity, was estimated at -19.6&amp;#177;3.4 Sv in 2015 and -35.2&amp;#177;3 Sv in 2017. A freshening and a decline in density mainly affecting the Subpolar Mode Water was observed in 2017. It was associated with a lower mode water&amp;#160; transport partly compensated by a higher transport of intermediate and Arctic waters. We further document each water mass contribution to the westward flow of the gyre and the structure of the ERRC and IC.&lt;/p&gt;

scholarly journals About the seasonal and fortnightly variabilities of the Mediterranean outflow

Ocean Science ◽  
2011 ◽  
Vol 7 (3) ◽  
pp. 421-428 ◽  
Author(s):  
C. Millot ◽  
J. Garcia-Lafuente
Keyword(s):  
Time Series ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Internal Tide ◽  
Atlantic Water ◽  
Strait Of Gibraltar ◽  
The North ◽  
Mediterranean Outflow ◽  
The Mediterranean

Abstract. CTD time series from the HYDRO-CHANGES programme and INGRES projects have been collected simultaneously (2004–2008) on the shelf of Morocco and at the sills of Camarinal and Espartel in the strait of Gibraltar. They provide information that supports results recently obtained from the analysis of the two former time series, as well as from a reanalysis of GIBEX CTD profiles (1985–1986). The outflow of Mediterranean Waters, which does not show a clear seasonal variability before entering the strait, strongly mixes within the strait, due mainly to the internal tide, with the seasonally variable inflow of Atlantic Water. The outflow thus gets marked seasonal and fortnightly variabilities within the strait. Furthermore, since the outflowing waters entering the strait display marked spatial heterogeneity and long-term temporal variabilities, accurately predicting the characteristics of the Mediterranean outflow into the North Atlantic Ocean appears almost impossible.

Taxonomy and biogeography of the genus Heteroteuthis (Mollusca: Cephalopoda) in the Atlantic Ocean

2010 ◽  
Vol 90 (2) ◽  
pp. 367-390 ◽  
Author(s):  
Natalie Rotermund ◽  
Jürgen Guerrero-Kommritz
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
South Atlantic Ocean ◽  
Full Description ◽  
The South ◽  
The North ◽  
South West ◽  
The North Atlantic ◽  
Definition Of

Two species of the bobtail squid Heteroteuthis are reported from the Atlantic Ocean, H. dispar in the North Atlantic Ocean and H. dagamensis in the South Atlantic Ocean. In total 58 individuals were examined, 23 belonging to the species Heteroteuthis dispar and 35 belonging to the species H. dagamensis. All specimens were captured during the Walther Herwig Expeditions 1966, 1968, 1976 and 1982. A full description of both sexes of H. dispar and H. dagamensis is provided. These two species can only be distinguished by means of the male's enlarged suckers on arm pair III. Females are not useful for taxonomic identifications and are morphologically identical in both species. The results do not support the definition of subgenera in this genus. This is the first report for Heteroteuthis dagamensis in the South-West Atlantic Ocean.

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