Coupled physical and biological modelling of the spring bloom in the North Atlantic (II): three dimensional bloom and post-bloom processes

Abstract. The North Atlantic spring bloom is one of the main events that lead to carbon export to the deep ocean and drive oceanic uptake of CO2 from the atmosphere. Here we use a suite of physical, bio-optical and chemical measurements made during the 2008 spring bloom to optimize and compare three different models of biological carbon export. The observations are from a Lagrangian float that operated south of Iceland from early April to late June, and were calibrated with ship-based measurements. The simplest model is representative of typical NPZD models used for the North Atlantic, while the most complex model explicitly includes diatoms and the formation of fast sinking diatom aggregates and cysts under silicate limitation. We carried out a variational optimization and error analysis for the biological parameters of all three models, and compared their ability to replicate the observations. The observations were sufficient to constrain most phytoplankton-related model parameters to accuracies of better than 15%. However, the lack of zooplankton observations leads to large uncertainties in model parameters for grazing. The simulated vertical carbon flux at 100 m depth is similar between models and agrees well with available observations, but at 600 m the simulated flux is much larger for the model with diatom aggregation. While none of the models can be formally rejected based on their misfit with the available observations, the model that includes export by diatom aggregation has slightly better fit to the observations and more accurately represents the mechanisms and timing of carbon export based on observations not included in the optimization. Thus models that accurately simulate the upper 100 m do not necessarily accurately simulate export to deeper depths.

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Net community production and export from Seaglider measurements in the North Atlantic after the spring bloom

Journal of Geophysical Research Oceans ◽

10.1002/2014jc010105 ◽

2014 ◽

Vol 119 (9) ◽

pp. 6121-6139 ◽

Cited By ~ 19

Author(s):

Matthew B. Alkire ◽

Craig Lee ◽

Eric D'Asaro ◽

Mary Jane Perry ◽

Nathan Briggs ◽

...

Keyword(s):

North Atlantic ◽

Spring Bloom ◽

Net Community Production ◽

The North ◽

The North Atlantic ◽

Community Production

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Timing of migratory baleen whales at the Azores in relation to the North Atlantic spring bloom

Marine Ecology Progress Series ◽

10.3354/meps09349 ◽

2011 ◽

Vol 440 ◽

pp. 267-279 ◽

Cited By ~ 46

Author(s):

F Visser ◽

KL Hartman ◽

GJ Pierce ◽

VD Valavanis ◽

J Huisman

Keyword(s):

North Atlantic ◽

Spring Bloom ◽

Baleen Whales ◽

The North ◽

The North Atlantic

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RAS-NAAD: 40-yr High-Resolution North Atlantic Atmospheric Hindcast for Multipurpose Applications (New Dataset for the Regional Mesoscale Studies in the Atmosphere and the Ocean)

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-19-0190.1 ◽

2020 ◽

Vol 59 (5) ◽

pp. 793-817 ◽

Cited By ~ 5

Author(s):

Alexander Gavrikov ◽

Sergey K. Gulev ◽

Margarita Markina ◽

Natalia Tilinina ◽

Polina Verezemskaya ◽

...

Keyword(s):

High Resolution ◽

Ocean Circulation ◽

North Atlantic ◽

Three Dimensional ◽

Vertical Direction ◽

Lateral Boundary Condition ◽

Three Dimensional Model ◽

Free Atmosphere ◽

The North ◽

The North Atlantic

AbstractWe present in this paper the results of the Russian Academy of Sciences North Atlantic Atmospheric Downscaling (RAS-NAAD) project, which provides a 40-yr 3D hindcast of the North Atlantic (10°–80°N) atmosphere at 14-km spatial resolution with 50 levels in the vertical direction (up to 50 hPa), performed with a regional setting of the WRF-ARW 3.8.1 model for the period 1979–2018 and forced by ERA-Interim as a lateral boundary condition. The dataset provides a variety of surface and free-atmosphere parameters at sigma model levels and meets many demands of meteorologists, climate scientists, and oceanographers working in both research and operational domains. Three-dimensional model output at 3-hourly time resolution is freely available to the users. Our evaluation demonstrates a realistic representation of most characteristics in both datasets and also identifies biases mostly in the ice-covered regions. High-resolution and nonhydrostatic model settings in NAAD resolve mesoscale dynamics first of all in the subpolar latitudes. NAAD also provides a new view of the North Atlantic extratropical cyclone activity with a much larger number of cyclones as compared with most reanalyses. It also effectively captures highly localized mechanisms of atmospheric moisture transports. Applications of NAAD to ocean circulation and wave modeling are demonstrated.

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Bioturbational structures in the North Atlantic: new approaches for studying cores

The Paleontological Society Special Publications ◽

10.1017/s2475262200006663 ◽

1992 ◽

Vol 6 ◽

pp. 106-106

Author(s):

Shaoping Fu ◽

Friedrich Werner

Keyword(s):

North Atlantic ◽

Sediment Cores ◽

Three Dimensional ◽

Bedding Plane ◽

Lateral Migration ◽

Core Diameter ◽

The North ◽

Biogenic Structures ◽

Sediment Cover ◽

The North Atlantic

General environmental correlation, established for trace fossils, is hard to apply to modern sediment cores, for which environmental factors can be measured directly - at least with regard to the top layers. Reasons for this difficulty are obvious: (1) Outcrop volume is limited by the core diameter. (2) Biogenic structures are hard to see, because they have not yet been “developed” by diagenetic processes. (3) Cores are traditionally studied in vertical cuts, in which search patterns parallel to bedding plane - typical for deep-sea environment - are poorly expressed. Therefore cores from the North Atlantic were studied not only by traditional X-ray radiography (both vertical and horizontal cuts), but by computer tomography (CT), which renders series of sections parallel to the bedding plane, as well as a three-dimensional picture, without destroying the valuable core.On the Iceland-Faeroe Ridge, the distribution of ichnocoenoses appears to be largely controlled by microenvironments in connection with local channel systems and their lateral migration. In a local, ridge-parallel channel system at the southern slope, a core from the NE flank shows a vertical alternation of Zoophycos, Trichichnus, and Planolites communities correlating with fluctuations of CaCO3 and the fraction >63μm. In contrast to this, on the opposite slope, sediments are uniform and dominated by Scolicia. On the colder N slope of the ridge, topography is more uniform and the water motion is sluggish. The characteristic and dominant ichnogenus is Chondrites. On top of the ridge the sediment cover becomes very thin, contains large amounts of dropstones, but still Chondrites is dominant.

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