On the use of a simple primary productivity model to assess the skill of a physical ocean model

2011 ◽  
Vol 40 (2) ◽  
Author(s):  
Lakshmi Kantha ◽  
Sandro Carniel ◽  
Carol Clayson ◽  
Mauro Sclavo
Keyword(s):  
Ocean Circulation ◽  
Primary Productivity ◽  
Circulation Model ◽  
Ecosystem Model ◽  
Ocean Model ◽  
Trophic Levels ◽  
Skill Assessment ◽  
Ecosystem Models ◽  
Color Data ◽  
Satellite Ocean Color

AbstractEcosystem models, used mainly in studying the interactions between different trophic levels, can also be used for ocean circulation model skill assessment, with the help of satellite ocean color data. This paper presents how the use of a simple NPZ primary productivity ecosystem model, coupled to a hydrodynamical model, can help assessing the skill of the physical ocean model in depicting realistically the prevailing mesoscale features of the upper layers of the Gulf of Mexico. Results indicate that the physical model effectively reproduces the mesoscale features of circulation underlying the resulting chlorophyll concentrations, especially when circulation fronts exist.

scholarly journals Central Mediterranean Sea forecast: effects of high-resolution atmospheric forcings

2006 ◽  
Vol 3 (3) ◽  
pp. 637-669 ◽  
Author(s):  
S. Natale ◽  
R. Sorgente ◽  
S. Gaberšek ◽  
A. Ribotti ◽  
A. Olita
Keyword(s):  
High Resolution ◽  
Ocean Circulation ◽  
Regional Scale ◽  
Circulation Model ◽  
Surface Current ◽  
Ocean Model ◽  
Central Mediterranean ◽  
Resolution Model ◽  
Atmospheric Forcings ◽  
Very High

Abstract. Ocean forecasts over the Central Mediterranean, produced by a near real time regional scale system, have been evaluated in order to assess their predictability. The ocean circulation model has been forced at the surface by a medium, high or very high resolution atmospheric forcing. The simulated ocean parameters have been compared with satellite data and they were found to be generally in good agreement. High and very high resolution atmospheric forcings have been able to form noticeable, although short-lived, surface current structures, due to their ability to detect transient atmospheric disturbances. The existence of the current structures has not been directly assessed due to lack of measurements. The ocean model in the slave mode was not able to develop dynamics different from the driving coarse resolution model which provides the boundary conditions.

scholarly journals Multi-grid algorithm for passive tracer transport in the NEMO ocean circulation model: a case study with the NEMO OGCM (version 3.6)

2020 ◽  
Vol 13 (11) ◽  
pp. 5465-5483
Author(s):  
Clément Bricaud ◽  
Julien Le Sommer ◽  
Gurvan Madec ◽  
Christophe Calone ◽  
Julie Deshayes ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Ocean Dynamics ◽  
Global Ocean ◽  
Passive Tracer ◽  
Tracer Transport ◽  
Ocean Circulation Model ◽  
Grid Algorithm

Abstract. Ocean biogeochemical models are key tools for both scientific and operational applications. Nevertheless the cost of these models is often expensive because of the large number of biogeochemical tracers. This has motivated the development of multi-grid approaches where ocean dynamics and tracer transport are computed on grids of different spatial resolution. However, existing multi-grid approaches to tracer transport in ocean modelling do not allow the computation of ocean dynamics and tracer transport simultaneously. This paper describes a new multi-grid approach developed for accelerating the computation of passive tracer transport in the Nucleus for European Modelling of the Ocean (NEMO) ocean circulation model. In practice, passive tracer transport is computed at runtime on a grid with coarser spatial resolution than the hydrodynamics, which reduces the CPU cost of computing the evolution of tracers. We describe the multi-grid algorithm, its practical implementation in the NEMO ocean model, and discuss its performance on the basis of a series of sensitivity experiments with global ocean model configurations. Our experiments confirm that the spatial resolution of hydrodynamical fields can be coarsened by a factor of 3 in both horizontal directions without significantly affecting the resolved passive tracer fields. Overall, the proposed algorithm yields a reduction by a factor of 7 of the overhead associated with running a full biogeochemical model like PISCES (with 24 passive tracers). Propositions for further reducing this cost without affecting the resolved solution are discussed.

Evaluating Effects of Observational Data Assimilation in General Ocean Circulation Model by Ensemble Kalman Filtering: Numerical Experiments with Synthetic Observations

2021 ◽  
pp. 50-66
Author(s):  
V. N. Stepanov ◽  
◽  
Yu. D. Resnyanskii ◽  
B. S. Strukov ◽  
A. A. Zelen’ko ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Observational Data ◽  
Ocean Circulation ◽  
Numerical Experiments ◽  
Turbulent Viscosity ◽  
Bottom Topography ◽  
Synthetic Data ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean

The quality of simulation of model fields is analyzed depending on the assimilation of various types of data using the PDAF software product assimilating synthetic data into the NEMO global ocean model. Several numerical experiments are performed to simulate the ocean–sea ice system. Initially, free model was run with different values of the coefficients of horizontal turbulent viscosity and diffusion, but with the same atmospheric forcing. The model output obtained with higher values of these coefficients was used to determine the first guess fields in subsequent experiments with data assimilation, while the model results with lower values of the coefficients were assumed to be true states, and a part of these results was used as synthetic observations. The results are analyzed that are assimilation of various types of observational data using the Kalman filter included through the PDAF to the NEMO model with real bottom topography. It is shown that a degree of improving model fields in the process of data assimilation is highly dependent on the structure of data at the input of the assimilation procedure.

scholarly journals Changes in Ocean Heat Content Caused by Wave-Induced Mixing in a High-Resolution Ocean Model

2018 ◽  
Vol 48 (5) ◽  
pp. 1139-1150 ◽  
Author(s):  
Lachlan Stoney ◽  
Kevin J. E. Walsh ◽  
Steven Thomas ◽  
Paul Spence ◽  
Alexander V. Babanin
Keyword(s):  
High Resolution ◽  
Ocean Circulation ◽  
Heat Content ◽  
Circulation Model ◽  
Additional Term ◽  
Ocean Model ◽  
Ocean Heat Content ◽  
Sea Surface ◽  
Wave Heights ◽  
Wave Induced

Abstract A parameterization of turbulent mixing from unbroken surface waves is included in a 16-yr simulation within a high-resolution ocean circulation model (MOM5). This “surface wave mixing” (SWM) derives from the wave orbital motion and is parameterized as an additional term in a k-epsilon model. We show that SWM leads to significant changes in sea surface temperatures but smaller changes in ocean heat content, and show the extent to which these changes can reduce pre-existing model biases with respect to observed data. Specifically, SWM leads to a widespread improvement in sea surface temperature in both hemispheres in summer and winter, while for ocean heat content the improvements are less clear. In addition, we show that introducing SWM can lead to an accumulation of wave-induced ocean heat content between years. While it has been well established that secular positive trends exist in global wave heights, we find that such trends are relatively unimportant in driving the accumulation of wave-induced ocean heat content. Rather, in response to the new source of mixing, the simulated ocean climate evolves toward a new equilibrium with greater total ocean heat content.

scholarly journals Impact of Parameterized Internal Wave Drag on the Semidiurnal Energy Balance in a Global Ocean Circulation Model

2016 ◽  
Vol 46 (5) ◽  
pp. 1399-1419 ◽  
Author(s):  
Maarten C. Buijsman ◽  
Joseph K. Ansong ◽  
Brian K. Arbic ◽  
James G. Richman ◽  
Jay F. Shriver ◽  
...  
Keyword(s):  
Internal Wave ◽  
Ocean Circulation ◽  
Deep Water ◽  
Mode Conversion ◽  
Circulation Model ◽  
Wave Drag ◽  
Ocean Model ◽  
Internal Tides ◽  
Global Ocean ◽  
Numerical Dissipation

AbstractThe effects of a parameterized linear internal wave drag on the semidiurnal barotropic and baroclinic energetics of a realistically forced, three-dimensional global ocean model are analyzed. Although the main purpose of the parameterization is to improve the surface tides, it also influences the internal tides. The relatively coarse resolution of the model of ~8 km only permits the generation and propagation of the first three vertical modes. Hence, this wave drag parameterization represents the energy conversion to and the subsequent breaking of the unresolved high modes. The total tidal energy input and the spatial distribution of the barotropic energy loss agree with the Ocean Topography Experiment (TOPEX)/Poseidon (TPXO) tidal inversion model. The wave drag overestimates the high-mode conversion at ocean ridges as measured against regional high-resolution models. The wave drag also damps the low-mode internal tides as they propagate away from their generation sites. Hence, it can be considered a scattering parameterization, causing more than 50% of the deep-water dissipation of the internal tides. In the near field, most of the baroclinic dissipation is attributed to viscous and numerical dissipation. The far-field decay of the simulated internal tides is in agreement with satellite altimetry and falls within the broad range of Argo-inferred dissipation rates. In the simulation, about 12% of the semidiurnal internal tide energy generated in deep water reaches the continental margins.

scholarly journals The Finite-volumE Sea ice–Ocean Model (FESOM2)

2016 ◽  
Author(s):  
Sergey Danilov ◽  
Dmitry Sidorenko ◽  
Qiang Wang ◽  
Thomas Jung
Keyword(s):  
Sea Ice ◽  
Ocean Circulation ◽  
Unstructured Mesh ◽  
Circulation Model ◽  
Ocean Model ◽  
Arbitrary Lagrangian Eulerian ◽  
Major Step ◽  
Vertical Coordinate ◽  
Intercomparison Project ◽  
Mesh Models

Abstract. Version 2 of the unstructured-mesh sea ice – ocean circulation model FESOM is presented. It builds upon FESOM1.4 (Wang et al., 2014, Geosci. Mod. Dev., 7, 663–693) but differs by its dynamical core (finite volumes instead of finite elements) and is formulated using the Arbitrary Lagrangian Eulerian (ALE) vertical coordinate, which increases model flexibility. The model inherits the framework and sea ice model from the previous version, which minimizes the efforts needed from a user to switch from one version to the other. The ocean states simulated with FESOM1.4 and FESOM2.0 driven by CORE-II forcing are compared on a mesh used for CORE-II intercomparison project. Additionally the performance on an eddy-permitting mesh with uniform resolution is discussed. The new version improves numerical efficiency of FESOM in terms of CPU time by at least three times while retaining its fidelity in simulating sea ice and ocean. From this it is argued that FESOM2.0 provides a major step forward in establishing unstructured-mesh models as valuable tools in climate research.

scholarly journals Ecological ReGional Ocean Model with vertically resolved sediments (ERGOM SED 1.0): coupling benthic and pelagic biogeochemistry of the south-western Baltic Sea

2019 ◽  
Vol 12 (1) ◽  
pp. 275-320 ◽  
Author(s):  
Hagen Radtke ◽  
Marko Lipka ◽  
Dennis Bunke ◽  
Claudia Morys ◽  
Jana Woelfel ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Marine Ecosystem ◽  
Nutrient Recycling ◽  
Three Dimensional ◽  
Ecosystem Model ◽  
Ocean Model ◽  
Ecosystem Models ◽  
Predictive Capacity ◽  
Sediment Types ◽  
Marine Ecosystem Model

Abstract. Sediments play an important role in organic matter mineralisation and nutrient recycling, especially in shallow marine systems. Marine ecosystem models, however, often only include a coarse representation of processes beneath the sea floor. While these parameterisations may give a reasonable description of the present ecosystem state, they lack predictive capacity for possible future changes, which can only be obtained from mechanistic modelling. This paper describes an integrated benthic–pelagic ecosystem model developed for the German Exclusive Economic Zone (EEZ) in the western Baltic Sea. The model is a hybrid of two existing models: the pelagic part of the marine ecosystem model ERGOM and an early diagenetic model by Reed et al. (2011). The latter one was extended to include the carbon cycle, a determination of precipitation and dissolution reactions which accounts for salinity differences, an explicit description of the adsorption of clay minerals, and an alternative pyrite formation pathway. We present a one-dimensional application of the model to seven sites with different sediment types. The model was calibrated with observed pore water profiles and validated with results of sediment composition, bioturbation rates and bentho-pelagic fluxes gathered by in situ incubations of sediments (benthic chambers). The model results generally give a reasonable fit to the observations, even if some deviations are observed, e.g. an overestimation of sulfide concentrations in the sandy sediments. We therefore consider it a good first step towards a three-dimensional representation of sedimentary processes in coupled pelagic–benthic ecosystem models of the Baltic Sea.

scholarly journals A nested Atlantic-Mediterranean Sea general circulation model for operational forecasting

Ocean Science ◽  
2009 ◽  
Vol 5 (4) ◽  
pp. 461-473 ◽  
Author(s):  
P. Oddo ◽  
M. Adani ◽  
N. Pinardi ◽  
C. Fratianni ◽  
M. Tonani ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
General Circulation Model ◽  
Ocean Circulation ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Lateral Boundary ◽  
The Mediterranean ◽  
The Impact

Abstract. A new numerical general circulation ocean model for the Mediterranean Sea has been implemented nested within an Atlantic general circulation model within the framework of the Marine Environment and Security for the European Area project (MERSEA, Desaubies, 2006). A 4-year twin experiment was carried out from January 2004 to December 2007 with two different models to evaluate the impact on the Mediterranean Sea circulation of open lateral boundary conditions in the Atlantic Ocean. One model considers a closed lateral boundary in a large Atlantic box and the other is nested in the same box in a global ocean circulation model. Impact was observed comparing the two simulations with independent observations: ARGO for temperature and salinity profiles and tide gauges and along-track satellite observations for the sea surface height. The improvement in the nested Atlantic-Mediterranean model with respect to the closed one is particularly evident in the salinity characteristics of the Modified Atlantic Water and in the Mediterranean sea level seasonal variability.

scholarly journals Stability of the Global Ocean Circulation: Basic Bifurcation Diagrams

2005 ◽  
Vol 35 (6) ◽  
pp. 933-948 ◽  
Author(s):  
Henk A. Dijkstra ◽  
Wilbert Weijer
Keyword(s):  
Ocean Circulation ◽  
General Circulation ◽  
Multiple Equilibria ◽  
Stable Solution ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Freshwater Flux ◽  
Surface Salinity ◽  
Global Ocean Circulation

Abstract A study of the stability of the global ocean circulation is performed within a coarse-resolution general circulation model. Using techniques of numerical bifurcation theory, steady states of the global ocean circulation are explicitly calculated as parameters are varied. Under a freshwater flux forcing that is diagnosed from a reference circulation with Levitus surface salinity fields, the global ocean circulation has no multiple equilibria. It is shown how this unique-state regime transforms into a regime with multiple equilibria as the pattern of the freshwater flux is changed in the northern North Atlantic Ocean. In the multiple-equilibria regime, there are two branches of stable steady solutions: one with a strong northern overturning in the Atlantic and one with hardly any northern overturning. Along the unstable branch that connects both stable solution branches (here for the first time computed for a global ocean model), the strength of the southern sinking in the South Atlantic changes substantially. The existence of the multiple-equilibria regime critically depends on the spatial pattern of the freshwater flux field and explains the hysteresis behavior as found in many previous modeling studies.

scholarly journals Scalability and some optimization of the Finite-volumE Sea ice-Ocean Model, Version 2.0 (FESOM2)

2019 ◽  
Author(s):  
Nikolay V. Koldunov ◽  
Vadym Aizinger ◽  
Natalja Rakowsky ◽  
Patrick Scholz ◽  
Dmitry Sidorenko ◽  
...  
Keyword(s):  
Sea Ice ◽  
Finite Volume ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Special Focus ◽  
Climate Modelling ◽  
Parallel Scalability ◽  
Model Version ◽  
Version 2.0

Abstract. A study of the scalability of the Finite-volumE Sea ice-Ocean circulation Model, Version 2.0 (FESOM2), the first mature global model of its kind formulated on unstructured meshes, is presented. This study includes an analysis of main computational kernels with a special focus on bottlenecks in parallel scalability. Several model enhancements, improving this scalability for large numbers of processes, are described and tested. Model grids at different resolutions are used on four HPC systems with differing computation and communication hardware to demonstrate model's scalability and throughput. Furthermore, strategies for improvements in parallel performance are presented and assessed. We show that in terms of throughput FESOM2.0 is on par with the state-of-the-art structured ocean models and in realistic eddy resolving configuration (1/10° resolution) can produce about 16 years per day on 14 000 cores. This suggests that unstructured-mesh models are becoming extremely competitive tools in high-resolution climate modelling. It is shown that main bottlenecks of FESOM parallel scalability are the two-dimensional components of the model, namely the computations of external (barotropic) mode and the sea-ice model. It is argued that these bottlenecks are shared with other general ocean circulation models.

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