scholarly journals A global viral oceanography database (gVOD)

2021 ◽  
Vol 13 (3) ◽  
pp. 1251-1271
Author(s):  
Le Xie ◽  
Wei Wei ◽  
Lanlan Cai ◽  
Xiaowei Chen ◽  
Yuhong Huang ◽  
...  
Keyword(s):  
North Atlantic ◽  
Marine Ecology ◽  
Global Ocean ◽  
Nutrient Cycles ◽  
Viral Production ◽  
Viral Abundance ◽  
The North ◽  
Random Forest Method ◽  
Order Of Magnitude ◽  
Marine Biosphere

Abstract. Virioplankton are a key component of the marine biosphere in maintaining diversity of microorganisms and stabilizing ecosystems. They also contribute greatly to nutrient cycles/cycling by releasing organic matter after lysis of hosts. In this study, we constructed the first global viral oceanography database (gVOD) by collecting 10 931 viral abundance (VA) data and 727 viral production (VP) data, along with host and relevant oceanographic parameters when available. Most VA data were obtained in the North Atlantic (32 %) and North Pacific (29 %) oceans, while the southeast Pacific and Indian oceans were quite undersampled. The VA in the global ocean was 1.17(±3.31)×107 particles mL−1. The lytic and lysogenic VP in the global ocean was 9.87(±24.16)×105 and 2.53(±8.64)×105 particlesmL-1h-1, respectively. Average VA in coastal oceans was higher than that in surface open oceans (3.61(±6.30)×107 versus 0.73(±1.24)×107 particles mL−1), while average VP in coastal and surface open oceans was close. Vertically, VA, lytic VP and lysogenic VP deceased from surface to deep oceans by about 1 order of magnitude. The total number of viruses in the global ocean estimated by bin-averaging and the random forest method was 1.56×1030 and 1.49×1030 particles, leading to an estimate of global ocean viral biomass at 35.9 and 34.4 Tg C, respectively. We expect that the gVOD will be a fundamental and very useful database for laboratory, field and modeling studies in marine ecology and biogeochemistry. The full gVOD database (Xie et al., 2020) is stored in PANGAEA (https://doi.org/10.1594/PANGAEA.915758).

scholarly journals A global viral oceanography database (gVOD)

2020 ◽  
Author(s):  
Le Xie ◽  
Wei Wei ◽  
Lanlan Cai ◽  
Xiaowei Chen ◽  
Yuhong Huang ◽  
...  
Keyword(s):  
North Atlantic ◽  
Deep Ocean ◽  
Marine Ecology ◽  
Global Ocean ◽  
Viral Production ◽  
Viral Abundance ◽  
The North ◽  
Southeast Pacific ◽  
Order Of Magnitude ◽  
Marine Biosphere

Abstract. Virioplankton is a key component of marine biosphere in maintaining diversity of microorganisms and stabilizing ecosystems. They also greatly contribute to nutrient recycles by releasing organic matter after lysis of hosts. In this study, we constructed the first global viral oceanography database (gVOD) by collecting 10 931 viral abundance (VA) data and 727 viral production (VP) data, along with host and other oceanographic parameters when available. Most VA data were obtained in the North Atlantic (32 %) and North Pacific Oceans (29 %), while the Southeast Pacific and Indian Oceans were quite under sampled. The VA in the global ocean was 1.17 (± 3.31) × 107 particles ml−1. The lytic and lysogenic VP in the global ocean was 9.87 (± 24.16) × 105 and 2.53 (± 8.64) × 105 particles ml−1 h−1, respectively. Average VA in coastal oceans was higher than that in surface open oceans [3.61 (± 6.30) × 107 versus 0.73 (± 1.24) × 107 particles ml−1], while average VP in coastal and surface open oceans was close. Vertically, VA, lytic and lysogenic VP deceased from surface to deep ocean by about one order of magnitude. The total number of viruses in the global ocean estimated by bin average and random forest methods was 1.4 × 1030 particles and 1.39 × 1030 particles, leading to an estimate of global ocean viral biomass at 32.3 and 32.2 Tg C, respectively. We expect that the gVOD will be a fundamental and very useful database for laboratory, field and modeling studies in marine ecology and biogeochemistry. The full gVOD database is stored at PANGAEA (a temporary link: https://www.pangaea.de/tok/19f9d7b496a00f57f491e639440708aee00b6a49).

scholarly journals Viral Abundance, Decay, and Diversity in the Meso- and Bathypelagic Waters of the North Atlantic

2007 ◽  
Vol 73 (14) ◽  
pp. 4429-4438 ◽  
Author(s):  
Verónica Parada ◽  
Eva Sintes ◽  
Hendrik M. van Aken ◽  
Markus G. Weinbauer ◽  
Gerhard J. Herndl
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Pulsed Field Gel Electrophoresis ◽  
Decay Rates ◽  
Leucine Incorporation ◽  
Taxon Richness ◽  
Viral Production ◽  
Viral Abundance ◽  
The North ◽  
Order Of Magnitude

ABSTRACT To elucidate the potential importance of deep-water viruses in controlling the meso- and bathypelagic picoplankton community, the abundance, decay rate, and diversity of the virioplankton community were determined in the meso- and bathypelagic water masses of the eastern part of the subtropical North Atlantic. Viral abundance averaged 1.4 × 106 ml−1 at around 100 m of depth and decreased only by a factor of 2 at 3,000 to 4,000 m of depth. In contrast, picoplankton abundance decreased by 1 order of magnitude to the Lower Deep Water (LDW; 3,500- to 5,000-m depth). The virus-to-picoplankton ratio increased from 9 at about 100 m of depth to 110 in the LDW. Mean viral decay rates were 3.5 × 10−3 h−1 between 900 m and 2,750 m and 1.1 × 10−3 h−1 at 4,000 m of depth, corresponding to viral turnover times of 11 and 39 days, respectively. Pulsed-field gel electrophoresis fingerprints obtained from the viral community between 2,400 m and 4,000 m of depth revealed a maximum of only four bands from 4,000 m of depth. Based on the high viral abundance and the low picoplankton production determined via leucine incorporation, we conclude that the viral production calculated from the viral decay is insufficient to maintain the high viral abundance in the deep North Atlantic. Rather, we propose that substantial allochthonous viral input or lysogenic or pseudolysogenic production is required to maintain the high viral abundance detected in the meso- and bathypelagic North Atlantic. Consequently, deep-water prokaryotes are apparently far less controlled in their abundance and taxon richness by lytic prokaryotic phages than the high viral abundance and the virus-to-picoplankton ratio would suggest.

The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation

2020 ◽  
Vol 33 (6) ◽  
pp. 2111-2130
Author(s):  
Woo Geun Cheon ◽  
Jong-Seong Kug
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North Pacific ◽  
Global Ocean ◽  
The North ◽  
Westerly Winds ◽  
The North Atlantic ◽  
Global Ocean Circulation ◽  
The Antarctic ◽  
The North Pacific

AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.

scholarly journals Marine productivity response to Heinrich events: a model-data comparison

2012 ◽  
Vol 8 (5) ◽  
pp. 1581-1598 ◽  
Author(s):  
V. Mariotti ◽  
L. Bopp ◽  
A. Tagliabue ◽  
M. Kageyama ◽  
D. Swingedouw
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Circulation Model ◽  
Global Ocean ◽  
Biogeochemical Model ◽  
Heinrich Events ◽  
The North ◽  
Heinrich Event ◽  
The North Atlantic ◽  
Marine Productivity

Abstract. Marine sediments records suggest large changes in marine productivity during glacial periods, with abrupt variations especially during the Heinrich events. Here, we study the response of marine biogeochemistry to such an event by using a biogeochemical model of the global ocean (PISCES) coupled to an ocean-atmosphere general circulation model (IPSL-CM4). We conduct a 400-yr-long transient simulation under glacial climate conditions with a freshwater forcing of 0.1 Sv applied to the North Atlantic to mimic a Heinrich event, alongside a glacial control simulation. To evaluate our numerical results, we have compiled the available marine productivity records covering Heinrich events. We find that simulated primary productivity and organic carbon export decrease globally (by 16% for both) during a Heinrich event, albeit with large regional variations. In our experiments, the North Atlantic displays a significant decrease, whereas the Southern Ocean shows an increase, in agreement with paleo-productivity reconstructions. In the Equatorial Pacific, the model simulates an increase in organic matter export production but decreased biogenic silica export. This antagonistic behaviour results from changes in relative uptake of carbon and silicic acid by diatoms. Reasonable agreement between model and data for the large-scale response to Heinrich events gives confidence in models used to predict future centennial changes in marine production. In addition, our model allows us to investigate the mechanisms behind the observed changes in the response to Heinrich events.

scholarly journals Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic

2018 ◽  
Vol 15 (8) ◽  
pp. 2289-2307 ◽  
Author(s):  
Nolwenn Lemaitre ◽  
Hélène Planquette ◽  
Frédéric Planchon ◽  
Géraldine Sarthou ◽  
Stéphanie Jacquet ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
North Atlantic ◽  
Deep Convection ◽  
Sediment Traps ◽  
Heterotrophic Activity ◽  
Physical Forcing ◽  
The North ◽  
Poc Export ◽  
Order Of Magnitude ◽  
The North Atlantic

Abstract. The remineralisation of sinking particles by prokaryotic heterotrophic activity is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May–June 2014) using the particulate biogenic barium (excess barium; Baxs) proxy. Important mesopelagic (100–1000 m) Baxs differences were observed along the transect depending on the intensity of past blooms, the phytoplankton community structure, and the physical forcing, including downwelling. The subpolar province was characterized by the highest mesopelagic Baxs content (up to 727 pmol L−1), which was attributed to an intense bloom averaging 6 mg chl a m−3 between January and June 2014 and by an intense 1500 m deep convection in the central Labrador Sea during the winter preceding the sampling. This downwelling could have promoted a deepening of the prokaryotic heterotrophic activity, increasing the Baxs content. In comparison, the temperate province, characterized by the lowest Baxs content (391 pmol L−1), was sampled during the bloom period and phytoplankton appear to be dominated by small and calcifying species, such as coccolithophorids. The Baxs content, related to oxygen consumption, was converted into a remineralisation flux using an updated relationship, proposed for the first time in the North Atlantic. The estimated fluxes were of the same order of magnitude as other fluxes obtained using independent methods (moored sediment traps, incubations) in the North Atlantic. Interestingly, in the subpolar and subtropical provinces, mesopelagic POC remineralisation fluxes (up to 13 and 4.6 mmol C m−2 d−1, respectively) were equalling and occasionally even exceeding upper-ocean POC export fluxes, deduced using the 234Th method. These results highlight the important impact of the mesopelagic remineralisation on the biological carbon pump of the studied area with a near-zero, deep (> 1000 m) carbon sequestration efficiency in spring 2014.

Efficient carbon drawdown allows for a high future carbon uptake in the North Atlantic

2021 ◽  
Author(s):  
Nadine Goris ◽  
Jerry Tjiputra ◽  
Are Ohlsen ◽  
Jörg Schwinger ◽  
Siv Lauvset ◽  
...  
Keyword(s):  
North Atlantic ◽  
High Latitude ◽  
Deep Convection ◽  
Deep Ocean ◽  
Nutrient Supply ◽  
Global Ocean ◽  
Carbon Uptake ◽  
Model Ensemble ◽  
The North ◽  
The North Atlantic

<p>As one of the major carbon sinks in the global ocean, the North Atlantic is a key player in mediating and ameliorating the ongoing global warming. Projections of the North Atlantic carbon sink in a high-CO<sub>2</sub> future vary greatly among models, with some showing that a slowdown in carbon uptake has already begun and others predicting that this slowdown will not occur until nearly 2100.</p><p>Discrepancies among models largely originate because of differences in the efficiency of the high-latitude transport of carbon from the surface to the deep ocean. This transport occurs through biological production, deep convection and subsequent transport via the deep western boundary current. For an ensemble of 11 CMIP5-models, we studied the efficiency of this transport and identified two indicators of contemporary model behavior that are highly correlated with a model´s projected future carbon-uptake. The first indicator is the high latitude summer pCO<sub>2</sub><sup>sea</sup>-anomaly of a model, which is tightly linked to winter mixing and nutrient supply, but also to deep convection. The second indicator is the fraction of the anthropogenic carbon-inventory stored below 1000-m depth, indicating how efficient carbon is transported into the deep ocean. By comparing to the observational database, these indicators allow us to better constrain the model ensemble, and demonstrate that the models with more efficient surface to deep transport are best aligned with current observations. These models also show the largest future North Atlantic carbon uptake, which we then conclude is the more plausible future evolution. We further study if the high correlations between our contemporary indicators and a model´s future North Atlantic carbon uptake is also upheld for the next model generation, CMIP6. We hypothesize that this is the case and that our indicators can not only help us to constrain the CMIP6 model ensemble but also inform us about progress made between CMIP5 and CMIP6 in terms of North Atlantic carbon uptake, winter mixing, nutrient supply, deep convection and transport of carbon into the deep ocean.</p>

Variability of the Oceanic Mixed Layer, 1960–2004

2008 ◽  
Vol 21 (5) ◽  
pp. 1029-1047 ◽  
Author(s):  
James A. Carton ◽  
Semyon A. Grodsky ◽  
Hailong Liu
Keyword(s):  
Mixed Layer ◽  
North Atlantic ◽  
Southern Oscillation ◽  
Mixed Layer Depth ◽  
Global Ocean ◽  
Boreal Summer ◽  
Layer Depth ◽  
The North ◽  
The North Atlantic ◽  
Mixed Layers

Abstract A new monthly uniformly gridded analysis of mixed layer properties based on the World Ocean Atlas 2005 global ocean dataset is used to examine interannual and longer changes in mixed layer properties during the 45-yr period 1960–2004. The analysis reveals substantial variability in the winter–spring depth of the mixed layer in the subtropics and midlatitudes. In the North Pacific an empirical orthogonal function analysis shows a pattern of mixed layer depth variability peaking in the central subtropics. This pattern occurs coincident with intensification of local surface winds and may be responsible for the SST changes associated with the Pacific decadal oscillation. Years with deep winter–spring mixed layers coincide with years in which winter–spring SST is low. In the North Atlantic a pattern of winter–spring mixed layer depth variability occurs that is not so obviously connected to local changes in winds or SST, suggesting that other processes such as advection are more important. Interestingly, at decadal periods the winter–spring mixed layers of both basins show trends, deepening by 10–40 m over the 45-yr period of this analysis. The long-term mixed layer deepening is even stronger (50–100 m) in the North Atlantic subpolar gyre. At tropical latitudes the boreal winter mixed layer varies in phase with the Southern Oscillation index, deepening in the eastern Pacific and shallowing in the western Pacific and eastern Indian Oceans during El Niños. In boreal summer the mixed layer in the Arabian Sea region of the western Indian Ocean varies in response to changes in the strength of the southwest monsoon.

scholarly journals North Atlantic SST Anomalies and the Cold North European Weather Events of Winter 2009/10 and December 2010

2014 ◽  
Vol 142 (2) ◽  
pp. 922-932 ◽  
Author(s):  
Jian Buchan ◽  
Joël J.-M. Hirschi ◽  
Adam T. Blaker ◽  
Bablu Sinha
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Cold Weather ◽  
Global Ocean ◽  
Northern Europe ◽  
Significant Shift ◽  
The North ◽  
Extreme Cold ◽  
The North Atlantic ◽  
Sst Anomalies

Abstract Northern Europe experienced consecutive periods of extreme cold weather in the winter of 2009/10 and in late 2010. These periods were characterized by a tripole pattern in North Atlantic sea surface temperature (SST) anomalies and exceptionally negative phases of the North Atlantic Oscillation (NAO). A global ocean–atmosphere general circulation model (OAGCM) is used to investigate the ocean’s role in influencing North Atlantic and European climate. Observed SST anomalies are used to force the atmospheric model and the resultant changes in atmospheric conditions over northern Europe are examined. Different atmospheric responses occur in the winter of 2009/10 and the early winter of 2010. These experiments suggest that North Atlantic SST anomalies did not significantly affect the development of the negative NAO phase in the cold winter of 2009/10. However, in November and December 2010 the large-scale North Atlantic SST anomaly pattern leads to a significant shift in the atmospheric circulation over the North Atlantic toward a NAO negative phase. Therefore, these results indicate that SST anomalies in November/December 2010 were particularly conducive to the development of a negative NAO phase, which culminated in the extreme cold weather conditions experienced over northern Europe in December 2010.

scholarly journals The mean state and variability of the North Atlantic circulation: a perspective from ocean reanalyses

2020 ◽  
Author(s):  
Laura Jackson ◽  
Clotilde Dubois ◽  
Gael Forget ◽  
Keith Haines ◽  
Matt Harrison ◽  
...  
Keyword(s):  
North Atlantic ◽  
Decadal Variability ◽  
Heat Content ◽  
Meridional Overturning Circulation ◽  
Global Ocean ◽  
The North ◽  
Ocean Reanalyses ◽  
The Mean ◽  
The North Atlantic ◽  
Mean State

<p>The observational network around the North Atlantic has improved significantly over the last few decades with the advent of Argo and satellite observations, and the more recent efforts to monitor the Atlantic Meridional Overturning Circulation (AMOC) using arrays such as RAPID and OSNAP. These have shown decadal timescale changes across the North Atlantic including in heat content, heat transport and the circulation. </p><p>However there are still significant gaps in the observational coverage, and significant uncertainties around some observational products. Ocean reanalyses integrate the observations with a dynamically consistent ocean model and are potentially tools that can be used to understand the observed changes. However the suitability of the reanalyses for the task must also be assessed.<br>We use an ensemble of global ocean reanalyses in comparison with observations in order to examine the mean state and interannual-decadal variability of the North Atlantic ocean since 1993. We assess how well the reanalyses are able to capture different processes and whether any understanding can be inferred. In particular we look at ocean heat content, transports, the AMOC and gyre strengths, water masses and convection. </p><p> </p>

scholarly journals NATO IN THE NEW STRATEGIC ENVIRONMENT: CYBER ATTACKS NOW COVERED BY ARTICLE 5 OF THE NORTH ATLANTIC TREATY

2014 ◽  
Vol 6 (2) ◽  
pp. 397-418 ◽  
Author(s):  
Grzegorz KOSTRZEWA-ZORBAS
Keyword(s):  
North Atlantic ◽  
The United States ◽  
Cyber Attacks ◽  
Global Ocean ◽  
Cyber Warfare ◽  
Security Environment ◽  
The North ◽  
The North Atlantic ◽  
Strategic Space ◽  
Article 5

The greatest change ever in the defence policy and military strategy of the North Atlantic Treaty Organisation occurred in 2014 in response to a series of major cyber attacks against NATO member states and partner states - Estonia in 2007, the United States and Georgia in 2008, and others in later years - and to a general transformation of the security environment in which cyberwar and other threats to cybersecurity gain rapidly in importance. At the 2014 Wales Summit, NATO recognised that cyber defence is part of its central task of collective defence and that Article 5 of the North Atlantic Treaty - ”The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all . . .” - can be invoked in the case of cyber attacks. This statement is the first and only expansion of the meaning of Article 5 and the first and only addition of a new type of warfare to the policy and strategy of NATO. After the change, the Alliance must face new challenges not less urgent and difficult than the old ones of kinetic warfare or weapons of mass destruction. This article addresses the broadest strategic context of the change. An analysis is made in the light of the global strategic thought and of the development of warfare through history. By entering the new strategic space of cyber warfare, NATO proves itself to be among the world’s most modern and advanced powers while, at the same time, it returns to the ancient - and lasting - tenet of strategy: information is not inferior to force. This way the Alliance moves away from Carl von Clausewitz and closer to Sun Zi. The recognition of cyberspace as a strategic space also corresponds to another influential idea in the heritage of strategy: the concept of the ”great common” the control of which is the key to the power over the world and over war and peace worldwide. Alfred Thayer Mahan considered the global ocean to be the ”great common” crossed by vital trade routes and by navies competing for superiority. Now cyberspace is as open, vital and fragile as the maritime space was in Mahan’s vision. Cyberwar also creates a promise and a temptation of a decisive strike - the first and last strike in a war - circumventing all military defences and paralysing the enemy country. It is a new version - less lethal or not, dependent on the tactics of cyber attacks in a cyber offensive - of the idea of strategic bombing and of the entire concept of air power, especially by its visionary Giulio Douhet, and then of nuclear strategy. Finally, the article provides two practical recommendations regarding the policy and structure of the North Atlantic Alliance in unfolding new era. Now NATO needs a speedy follow-on to the breakthrough decision of the Wales Summit. Cyber defence should be fully integrated into the next Strategic Concept which is expected in or around 2020 but could be worked out sooner because of the accelerating transition of the security environment. NATO should also consider establishing a global Cyber Command to maintain the initiative and to assure the credibility of the enlarged meaning of Article 5 of the North Atlantic Treaty. This credibility will be immediately, continuously and comprehensively tested by many players of the global game.

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