Large-scale impacts of submesoscale dynamics on phytoplankton: Local and remote effects

Lévy, Marina; Iovino, Doroteaciro; Resplandy, Laure; Klein, Patrice; Madec, Gurvan; Tréguier, Anne‐Marie; Masson, Sébastien; Takahashi, Keiko

doi:10.1016/j.ocemod.2011.12.003

Cited by 127 publications

(136 citation statements)

References 68 publications

Supporting

Mentioning

131

Contrasting

Order By: Relevance

“…In the ETNA both eddy types have in common that in their center the ML base rises towards shallow depth (50 to 100 m), which in turn favors biological productivity in the euphotic zone (Falkowski et al, 1991;McGillicuddy et al, 1998). In addition, an enhanced vertical flux of nutrients within or at the periphery of the eddies due to submesoscale instabilities is expected to occur (Brannigan et al, 2015;Karstensen et al, 2016;Lévy et al, 2012;Martin and Richards, 2001;Omand et al, 2015). As a consequence the eddies establish a specific ecosystem of high primary production, particle load and degradation processes, and even unexpected nitrogen loss processes (Löscher et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…The key point in changing non-conservative tracers in the eddy cores is the physicalbiological coupling, which is strongly linked to the vertical velocities of submesoscale physics, stimulating primary production (upward nutrient flux) in particular under oligotrophic conditions (Falkowski et al, 1991;Levy et al, 2001;McGillicuddy et al, 2007). The detailed understanding of the physical and biogeochemical processes and their linkage in eddies is still limited (Lévy et al, 2012). Consequently the relative magnitude of eddy-dependent vertical nutrient flux, primary productivity and associated enhanced oxygen consumption or nitrogen fixation/denitrification in the eddy cores and accordingly the contribution to the large-scale oxygen or nutrient distribution is fairly unknown.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of “dead-zone” eddies in the eastern tropical North Atlantic

Schütte¹,

Karstensen²,

Krahmann³

et al. 2016

Biogeosciences

101

View full text Add to dashboard Cite

Abstract. Localized open-ocean low-oxygen "dead zones" in the eastern tropical North Atlantic are recently discovered ocean features that can develop in dynamically isolated water masses within cyclonic eddies (CE) and anticyclonic modewater eddies (ACME). Analysis of a comprehensive oxygen dataset obtained from gliders, moorings, research vessels and Argo floats reveals that "dead-zone" eddies are found in surprisingly high numbers and in a large area from about 4 to 22 • N, from the shelf at the eastern boundary to 38 • W. In total, 173 profiles with oxygen concentrations below the minimum background concentration of 40 µmol kg −1 could be associated with 27 independent eddies (10 CEs; 17 ACMEs) over a period of 10 years. Lowest oxygen concentrations in CEs are less than 10 µmol kg −1 while in ACMEs even suboxic (< 1 µmol kg −1 ) levels are observed. The oxygen minimum in the eddies is located at shallow depth from 50 to 150 m with a mean depth of 80 m. Compared to the surrounding waters, the mean oxygen anomaly in the core depth range (50 and 150 m) for CEs (ACMEs) is −38 (−79) µmol kg −1 . North of 12 • N, the oxygen-depleted eddies carry anomalously low-salinity water of South Atlantic origin from the eastern boundary upwelling region into the open ocean. Here water mass properties and satellite eddy tracking both point to an eddy generation near the eastern boundary. In contrast, the oxygen-depleted eddies south of 12 • N carry weak hydrographic anomalies in their cores and seem to be generated in the open ocean away from the boundary. In both regions a decrease in oxygen from east to west is identified supporting the en-route creation of the low-oxygen core through a combination of high productivity in the eddy surface waters and an isolation of the eddy cores with respect to lateral oxygen supply. Indeed, eddies of both types feature a cold sea surface temperature anomaly and enhanced chlorophyll concentrations in their center. The low-oxygen core depth in the eddies aligns with the depth of the shallow oxygen minimum zone of the eastern tropical North Atlantic. Averaged over the whole area an oxygen reduction of 7 µmol kg −1 in the depth range of 50 to 150 m (peak reduction is 16 µmol kg −1 at 100 m depth) can be associated with the dispersion of the eddies. Thus the locally increased oxygen consumption within the eddy cores enhances the total oxygen consumption in the open eastern tropical North Atlantic Ocean and seems to be an contributor to the formation of the shallow oxygen minimum zone.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of “dead-zone” eddies in the eastern tropical North Atlantic

Schütte¹,

Karstensen²,

Krahmann³

et al. 2016

Biogeosciences

101

View full text Add to dashboard Cite

show abstract

“…We started from identical distributions of biomass for all plankton types, and from nutrient fields derived from [34]. Model outputs were saved every 2 days (48 h averages).…”

Section: Off-line Model Integrationmentioning

confidence: 99%

The dynamical landscape of marine phytoplankton diversity

Lévy

Jahn

Dutkiewicz

et al. 2015

J. R. Soc. Interface.

View full text Add to dashboard Cite

Observations suggest that the landscape of marine phytoplankton assemblage might be strongly heterogeneous at the dynamical mesoscale and submesoscale (10-100 km, days to months), with potential consequences in terms of global diversity and carbon export. But these variations are not well documented as synoptic taxonomic data are difficult to acquire. Here, we examine how phytoplankton assemblage and diversity vary between mesoscale eddies and submesoscale fronts. We use a multi-phytoplankton numerical model embedded in a mesoscale flow representative of the North Atlantic. Our model results suggest that the mesoscale flow dynamically distorts the niches predefined by environmental contrasts at the basin scale and that the phytoplankton diversity landscape varies over temporal and spatial scales that are one order of magnitude smaller than those of the basin-scale environmental conditions. We find that any assemblage and any level of diversity can occur in eddies and fronts. However, on a statistical level, the results suggest a tendency for larger diversity and more fast-growing types at fronts, where nutrient supplies are larger and where populations of adjacent water masses are constantly brought into contact; and lower diversity in the core of eddies, where water masses are kept isolated long enough to enable competitive exclusion.

show abstract

“…Capet et al, 2008a;Klein et al, 2008) and are observed in the wintertime midlatitude ocean (Shcherbina et al, 2013;Chapter 5). These submesoscale flows at scales 1-100 km are associated with large vertical fluxes of both physical and biogeochemical tracers that have been argued to regulate the oceanic heat and carbon uptake in global warming scenarios (Capet et al, 2008a;Klein and Lapeyre, 2009;Ferrari, 2011;Lévy et al, 2012;Mahadevan, 2014). Current global ocean models do not resolve submesoscale flows, so these fluxes must be represented by parameterizations that should be based on physical understanding.…”

Section: Introductionmentioning

confidence: 99%

Submesoscale turbulence in the upper ocean

Callies¹

2016

View full text Add to dashboard Cite

Submesoscale flows, current systems 1-100 km in horizontal extent, are increasingly coming into focus as an important component of upper-ocean dynamics. A range of processes have been proposed to energize submesoscale flows, but which process dominates in reality must be determined observationally. We diagnose from observed flow statistics that in the thermocline the dynamics in the submesoscale range transition from geostrophic turbulence at large scales to inertia-gravity waves at small scales, with the transition scale depending dramatically on geographic location. A similar transition is shown to occur in the atmosphere, suggesting intriguing similarities between atmospheric and oceanic dynamics. We furthermore diagnose from upper-ocean observations a seasonal cycle in submesoscale turbulence: fronts and currents are more energetic in the deep wintertime mixed layer than in the summertime seasonal thermocline. This seasonal cycle hints at the importance of baroclinic mixed layer instabilities in energizing submesoscale turbulence in winter. To better understand this energization, three aspects of the dynamics of baroclinic mixed layer instabilities are investigated. First, we formulate a quasigeostrophic model that describes the linear and nonlinear evolution of these instabilities. The simple model reproduces the observed wintertime distribution of energy across scales and depth, suggesting it captures the essence of how the submesoscale range is energized in winter. Second, we investigate how baroclinic instabilities are affected by convection, which is generated by atmospheric forcing and dominates the mixed layer dynamics at small scales. It is found that baroclinic instabilities are remarkably resilient to the presence of convection and develop even when rapid overturns keep the mixed layer unstratified. Third, we discuss the restratification induced by baroclinic mixed layer instabilities. We show that the rate of restratification depends on characteristics of the baroclinic eddies themselves, a dependence not captured by a previously proposed parameterization. These insights sharpen our understanding of submesoscale dynamics and can help focus future inquiry into whether and how submesoscale flows influence the ocean's role in climate.Thesis supervisor: Raffaele Ferrari Title: Breene M. Kerr Professor of Oceanography

show abstract

Large-scale impacts of submesoscale dynamics on phytoplankton: Local and remote effects

Cited by 127 publications

References 68 publications

Characterization of “dead-zone” eddies in the eastern tropical North Atlantic

Characterization of “dead-zone” eddies in the eastern tropical North Atlantic

The dynamical landscape of marine phytoplankton diversity

Submesoscale turbulence in the upper ocean

Contact Info

Product

Resources

About