Three-dimensional view of the large-scale tropospheric ozone distribution over the North Atlantic Ocean during summer

1996 ◽  
Vol 101 (D22) ◽  
pp. 29305-29316 ◽  
Author(s):  
P. Kasibhatla ◽  
H. Levy ◽  
A. Klonecki ◽  
W. L. Chameides
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Tropospheric Ozone ◽  
Large Scale ◽  
North Atlantic Ocean ◽  
Three Dimensional ◽  
The North ◽  
Ozone Distribution ◽  
The North Atlantic

scholarly journals Assimilation of chlorophyll data into a stochastic ensemble simulation for the North Atlantic ocean

2020 ◽  
Author(s):  
Yeray Santana-Falcón ◽  
Pierre Brasseur ◽  
Jean Michel Brankart ◽  
Florent Garnier
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Three Dimensional ◽  
State Variables ◽  
Sensitivity Experiment ◽  
The North ◽  
Assimilation Process ◽  
The North Atlantic ◽  
One Year

<p>Satellite-derived surface chlorophyll data are daily assimilated into a three-dimensional 24 member ensemble configuration of an online-coupled NEMO-PISCES model for the North Atlantic ocean. A one-year multivariate assimilation experiment is performed to evaluate the impacts on analyses and forecast ensembles. Our results demonstrate that the integration of data improves surface analysis and forecast chlorophyll representation in a major part of the model domain, where the assimilated simulation outperforms the probabilistic skills of a non-assimilated analogous simulation. However, improvements are dependent on the reliability of the prior free ensemble. A regional diagnosis shows that surface chlorophyll is overestimated in the northern limit of the subtropical North Atlantic, where the prior ensemble spread does not cover the observation's variability. There, the system cannot deal with corrections that alter the equilibrium between the observed and unobserved state variables producing instabilities that propagate into the forecast. To alleviate these inconsistencies, a one-month sensitivity experiment in which the assimilation process is only applied to model fluctuations is performed. Results suggest the use of this methodology may decrease the effect of corrections on the correlations between state vectors. Overall, the experiments presented here evidence the need of refining the description of model's uncertainties according to the biogeochemical characteristics of each oceanic region.</p>

scholarly journals Assimilation of chlorophyll data into a stochastic ensemble simulation for the North Atlantic Ocean

Ocean Science ◽  
2020 ◽  
Vol 16 (5) ◽  
pp. 1297-1315
Author(s):  
Yeray Santana-Falcón ◽  
Pierre Brasseur ◽  
Jean Michel Brankart ◽  
Florent Garnier
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Three Dimensional ◽  
State Variables ◽  
Sensitivity Experiment ◽  
The North ◽  
Ecosystem Studies ◽  
Interaction Scheme ◽  
The North Atlantic

Abstract. Satellite-derived surface chlorophyll data are assimilated daily into a three-dimensional 24-member ensemble configuration of an online-coupled NEMO (Nucleus for European Modeling of the Ocean)–PISCES (Pelagic Interaction Scheme of Carbon and Ecosystem Studies) model for the North Atlantic Ocean. A 1-year multivariate assimilation experiment is performed to evaluate the impacts on analyses and forecast ensembles. Our results demonstrate that the integration of data improves surface analysis and forecast chlorophyll representation in a major part of the model domain, where the assimilated simulation outperforms the probabilistic skills of a non-assimilated analogous simulation. However, improvements are dependent on the reliability of the prior free ensemble. A regional diagnosis shows that surface chlorophyll is overestimated in the northern limit of the subtropical North Atlantic, where the prior ensemble spread does not cover the observation's variability. There, the system cannot deal with corrections that alter the equilibrium between the observed and unobserved state variables producing instabilities that propagate into the forecast. To alleviate these inconsistencies, a 1-month sensitivity experiment in which the assimilation process is only applied to model fluctuations is performed. Results suggest the use of this methodology may decrease the effect of corrections on the correlations between state vectors. Overall, the experiments presented here evidence the need of refining the description of model's uncertainties according to the biogeochemical characteristics of each oceanic region.

Detection and characterization of SCVs in the North Atlantic

2020 ◽  
Author(s):  
Ashwita Chouksey ◽  
Xavier Carton ◽  
Jonathan Gula
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Large Scale ◽  
North Atlantic Ocean ◽  
The North ◽  
Place Of Origin ◽  
Different Depths ◽  
The North Atlantic ◽  
Transport And Mixing

<p>In recent years, the oceanographic community has devoted considerable interest to the study of SCVs (Submesoscale Coherent Vortices, i.e. vortices with radii between 2-30 km, below the first internal radius of deformation); indeed, both mesoscale and submesoscale eddies contribute to the transport and mixing of water masses and of tracers (active and passive), affecting the heat transport, the ventilation pathways and thus having an impact on the large scale circulation.</p><p>In different areas of the ocean, SCVs have been detected, via satellite or in-situ measurements, at the surface or at depth. From these data, SCVs were found to be of different shapes and sizes depending on their place of origin and on their location. Here, we will concentrate rather on the SCVs at depth.</p><p>In this study, we use a high resolution simulation of the North Atlantic ocean with the ROMS-CROCO model. In this simulation, we also identify the SCVs at different depths and densities; we analyse their site and mechanism of generation, their drift, the physical processes conducting to this drift and their interactions with the surrounding flows. We also quantify their physical characteristics (radius, thickness, intensity/vorticity, bias in polarity: cyclones versus anticyclones). We provide averages for these characteristics and standard deviations. </p><p>We compare the model results with the observational data, in particular temperature and salinity profiles from Argo floats and velocity data from currentmeter recordings. </p><p>This study is a first step in the understanding of the formation, occurrences and structure of SCVs in the North Atlantic Ocean, of help to improve their in-situ sampling.</p>

Mapping Tectonic Deformation in the Crust and Upper Mantle Beneath Europe and the North Atlantic Ocean

Science ◽  
2013 ◽  
Vol 341 (6148) ◽  
pp. 871-875 ◽  
Author(s):  
Hejun Zhu ◽  
Jeroen Tromp
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Three Dimensional ◽  
Surface Strain ◽  
Tectonic Deformation ◽  
Crust And Upper Mantle ◽  
The North ◽  
Ductile Flow ◽  
The North Atlantic

We constructed a three-dimensional azimuthally anisotropic model of Europe and the North Atlantic Ocean based on adjoint seismic tomography. Several features are well correlated with historical tectonic events in this region, such as extension along the North Atlantic Ridge, trench retreat in the Mediterranean, and counterclockwise rotation of the Anatolian Plate. Beneath northeastern Europe, the direction of the fast anisotropic axis follows trends of ancient rift systems older than 350 million years, suggesting “frozen-in” anisotropy related to the formation of the craton. Local anisotropic strength profiles identify the brittle-ductile transitions in lithospheric strength. In continental regions, these profiles also identify the lower crust, characterized by ductile flow. The observed anisotropic fabric is generally consistent with the current surface strain rate measured by geodetic surveys.

scholarly journals Assimilation of chlorophyll data into a stochastic ensemble simulation for the North Atlantic ocean

2020 ◽  
Author(s):  
Yeray Santana-Falcón ◽  
Pierre Brasseur ◽  
Jean Michel Brankart ◽  
Florent Garnier
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Three Dimensional ◽  
State Variables ◽  
Sensitivity Experiment ◽  
The North ◽  
Assimilation Process ◽  
The North Atlantic ◽  
One Year

Abstract. Satellite-derived surface chlorophyll data are daily assimilated into a three-dimensional 24 member ensemble configuration of an online-coupled NEMO-PISCES model for the North Atlantic ocean. A one-year multivariate assimilation experiment is performed to evaluate the impacts on analyses and forecast ensembles. Our results demonstrate that the integration of data improves surface analysis and forecast chlorophyll representation in a major part of the model domain, where the assimilated simulation outperforms the probabilistic skills of a non-assimilated analogous simulation. However, improvements are dependent on the reliability of the prior free ensemble. A regional diagnosis shows that surface chlorophyll is overestimated in the northern limit of the subtropical North Atlantic, where the prior ensemble spread does not cover the observation's variability. There, the system cannot deal with corrections that alter the equilibrium between the observed and unobserved state variables producing instabilities that propagate into the forecast. To alleviate these inconsistencies, a one-month sensitivity experiment in which the assimilation process is only applied to model fluctuations is performed. Results suggest the use of this methodology may decrease the effect of corrections on the correlations between state vectors. Overall, the experiments presented here evidence the need of refining the description of model's uncertainties according to the biogeochemical characteristics of each oceanic region.

On the North Atlantic Ocean Heat Content Change between 1955–70 and 1980–95

2012 ◽  
Vol 25 (10) ◽  
pp. 3619-3628 ◽  
Author(s):  
Xiaoming Zhai ◽  
Luke Sheldon
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Gulf Stream ◽  
Large Scale ◽  
North Atlantic Ocean ◽  
Heat Content ◽  
Ocean Heat Content ◽  
The North ◽  
Content Change ◽  
The North Atlantic

Abstract The upper-ocean heat content of the North Atlantic has undergone significant changes over the last 50 years but the underlying physical mechanisms are not yet well understood. In the present study, the authors examine the North Atlantic ocean heat content change in the upper 700 m between the 1955–70 and 1980–95 periods. Consistent with previous studies, the large-scale pattern consists of warming of the tropics and subtropics and cooling of the subpolar ocean. However, this study finds that the most significant heat content change in the North Atlantic during these two time periods is the warming of the Gulf Stream region. Numerical experiments strongly suggest that this warming in the Gulf Stream region is largely driven by changes of the large-scale wind forcing. Furthermore, the increased ocean heat content in the Gulf Stream region appears to feedback on to the atmosphere, resulting in warmer surface air temperature and enhanced precipitation there.

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