A comparison of temperature, salinity, and chlorofluorocarbon observations with results from a 1° resolution three-dimensional global ocean model

1998 ◽  
Vol 103 (C1) ◽  
pp. 1099-1119 ◽  
Author(s):  
A. P. Craig ◽  
J. L. Bullister ◽  
D. E. Harrison ◽  
R. M. Chervin ◽  
A. J. Semtner
Keyword(s):  
Three Dimensional ◽  
Ocean Model ◽  
Global Ocean

scholarly journals A parameterization of local and remote tidal mixing

2020 ◽  
Author(s):  
Casimir de Lavergne ◽  
Clément Vic ◽  
Gurvan Madec ◽  
Fabien Roquet ◽  
Amy Waterhouse ◽  
...  
Keyword(s):  
Vertical Mixing ◽  
Three Dimensional ◽  
Internal Tide ◽  
Ocean Model ◽  
Internal Tides ◽  
Tidal Mixing ◽  
Global Ocean ◽  
Energy Conserving ◽  
Energy Constrained ◽  
Lagrangian Tracking

<p>Vertical mixing is often regarded as the Achilles’ heel of ocean models. In particular, few models include a comprehensive and energy-constrained parameterization of mixing by internal ocean tides. Here, we present an energy-conserving mixing scheme which accounts for the local breaking of high-mode internal tides and the distant dissipation of low-mode internal tides. The scheme relies on four static two-dimensional maps of internal tide dissipation, constructed using mode-by-mode Lagrangian tracking of energy beams from sources to sinks. Each map is associated with a distinct dissipative process and a corresponding vertical structure. Applied to an observational climatology of stratification, the scheme produces a global three-dimensional map of dissipation which compares well with available microstructure observations and with upper-ocean finestructure mixing estimates. Implemented in the NEMO global ocean model, the scheme improves the representation of deep water-mass transformation and obviates the need for a constant background diffusivity.</p>

scholarly journals Assessment of a NEMO-based hydrodynamic modelling system for the Great Lakes

2012 ◽  
Vol 47 (3-4) ◽  
pp. 198-214 ◽  
Author(s):  
Frederic Dupont ◽  
Padala Chittibabu ◽  
Vincent Fortin ◽  
Yerubandi R. Rao ◽  
Youyu Lu
Keyword(s):  
Great Lakes ◽  
Thermal Structure ◽  
Three Dimensional ◽  
Multiscale Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Central Basin ◽  
Surface Mixed Layer ◽  
Global Environmental ◽  
Modelling System

Environment Canada recently developed a coupled lake–atmosphere–hydrological modelling system for the Laurentian Great Lakes. This modelling system consists of the Canadian Regional Deterministic Prediction System (RDPS), which is based on the Global Environmental Multiscale model (GEM), the MESH (Modélisation Environnementale Surface et Hydrologie) surface and river routing model, and a hydrodynamic model based on the three-dimensional global ocean model Nucleus for European Modelling of the Ocean (NEMO). This paper describes the performance of the NEMO model in the Great Lakes. The model was run from 2004 to 2009 with atmospheric forcing from GEM and river forcing from the MESH modelling system for the Great Lakes region and compared with available observations in selected lakes. The NEMO model is able to produce observed variations of lake levels, ice concentrations, lake surface temperatures, surface currents and vertical thermal structure reasonably well in most of the Great Lakes. However, the model produced a diffused thermocline in the central basin of Lake Erie. The model predicted evaporation is relatively strong in the upper lakes. Preliminary results of the modelling system indicate that the model needs further improvements in atmospheric–lake exchange bulk formulae and surface mixed layer physics.

scholarly journals THREE-DIMENSIONAL SIMULATION OF TIDAL CURRENT IN LAMPUNG BAY: DIAGNOSTIC NUMERICAL EXPERIMENTS

2010 ◽  
Vol 3 (-) ◽  
Author(s):  
Alan Frendy Koropitan ◽  
Safwan Hadi ◽  
Ivonne M.Radjawane
Keyword(s):  
Tidal Current ◽  
Lower Layer ◽  
Three Dimensional ◽  
Ocean Model ◽  
Residual Current ◽  
Global Ocean ◽  
Open Boundary ◽  
Ocean Tide ◽  
Tidal Elevation ◽  
Diagnostic Mode

Princeton Ocean Model (POM) was used to calculate the tidal current in Lampung Bay using diagnostic mode. The model was forced by tidal elevation, which was given along the open boundary using a global ocean tide model-ORITIDE. The computed tidal elevation at St. 1 and St 2 are in a good agreement with the observed data, but the computed tidal current at St 1 at depth 2 m is not good and moderate approximation is showed at depth 10 m. Probably, it was influenced by non-linier effect of coastal geometry and bottom friction because of the position of current meter, mooring closed to the coastline. Generally, the calculated tidal currents in all layers show that the water flows into the bay during flood tide and goes out from the bay during ebb tide. The tidal current becomes strong when passing through the narrow passage of Pahawang Strait. The simulation of residual tidal current with particular emphasis on predominant contituent of M2 shows a strong inflow from the western part of the bay mouth, up to the central part of the bay, then the strong residual current deflects to the southeast and flows out from the eastern part of the bay mouth. This flow pattern is apparent in the upper and lower layer. The other part flows to the bay head and froms an antic lockwise circulation in the small basin region of the bay head. The anticlockwise circulations are showed in the upper layer and disappear in the layer near the bottom. Keywords: POM, diagnostic mode, tidal current, residual current, Lampung Ba.

scholarly journals Skill tests of three-dimensional tidal currents in a global ocean model: A look at the North Atlantic

2012 ◽  
Vol 117 (C8) ◽  
pp. n/a-n/a ◽  
Author(s):  
Patrick G. Timko ◽  
Brian K. Arbic ◽  
James G. Richman ◽  
Robert B. Scott ◽  
E. Joseph Metzger ◽  
...  
Keyword(s):  
North Atlantic ◽  
Three Dimensional ◽  
Ocean Model ◽  
Tidal Currents ◽  
Global Ocean ◽  
The North ◽  
The North Atlantic

scholarly journals Thermodynamic Analysis of Ocean Circulation

2007 ◽  
Vol 37 (8) ◽  
pp. 2038-2052 ◽  
Author(s):  
J. Nycander ◽  
J. Nilsson ◽  
K. Döös ◽  
G. Broström
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Three Dimensional ◽  
Boussinesq Equations ◽  
Ocean Model ◽  
Global Ocean ◽  
Small Scale ◽  
Ekman Pumping ◽  
Overturning Circulation ◽  
Thermodynamic Work

Abstract Calculating a streamfunction as function of depth and density is proposed as a new way of analyzing the thermodynamic character of the overturning circulation in the global ocean. The sign of an overturning cell in this streamfunction directly shows whether it is driven mechanically by large-scale wind stress or thermally by heat conduction and small-scale mixing. It is also shown that the integral of this streamfunction gives the thermodynamic work performed by the fluid. The analysis is also valid for the Boussinesq equations, although formally there is no thermodynamic work in an incompressible fluid. The proposed method is applied both to an idealized coarse-resolution three-dimensional numerical ocean model, and to the realistic high-resolution Ocean Circulation and Climate Advanced Model (OCCAM). It is shown that the overturning circulation in OCCAM between the 200- and 1000-m depth is dominated by a thermally indirect cell of 24 Sverdrups (1 Sv ≡ 106 m3 s−1), forced by Ekman pumping. In the densest and deepest waters there is a thermally direct cell of 18 Sv, which requires a forcing by around 100 GW of parameterized small-scale mixing.

scholarly journals Estimating Eddy Stresses by Fitting Dynamics to Observations Using a Residual-Mean Ocean Circulation Model and Its Adjoint

2005 ◽  
Vol 35 (10) ◽  
pp. 1891-1910 ◽  
Author(s):  
David Ferreira ◽  
John Marshall ◽  
Patrick Heimbach
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Three Dimensional ◽  
Circulation Model ◽  
Eddy Diffusivity ◽  
Ocean Model ◽  
Global Ocean ◽  
Western Boundary ◽  
Mean Flow ◽  
Ocean Circulation Model

Abstract A global ocean circulation model is formulated in terms of the “residual mean” and used to study eddy–mean flow interaction. Adjoint techniques are used to compute the three-dimensional eddy stress field that minimizes the departure of the coarse-resolution model from climatological observations of temperature. The resulting 3D maps of eddy stress and residual-mean circulation yield a wealth of information about the role of eddies in large-scale ocean circulation. In eddy-rich regions such as the Southern Ocean, the Kuroshio, and the Gulf Stream, eddy stresses have an amplitude comparable to the wind stress, of order 0.2 N m−2, and carry momentum from the surface down to the bottom, where they are balanced by mountain form drag. From the optimized eddy stress, 3D maps of horizontal eddy diffusivity κ are inferred. The diffusivities have a well-defined large-scale structure whose prominent features are 1) large values of κ (up to 4000 m2 s−1) in the western boundary currents and on the equatorial flank of the Antarctic Circumpolar Current and 2) a surface intensification of κ, suggestive of a dependence on the stratification N 2. It is shown that implementation of an eddy parameterization scheme in which the eddy diffusivity has an N 2 dependence significantly improves the climatology of the ocean model state relative to that obtained using a spatially uniform diffusivity.

Application of the Sequential Three-Dimensional Variational Method to Assimilating SST in a Global Ocean Model

2008 ◽  
Vol 25 (6) ◽  
pp. 1018-1033 ◽  
Author(s):  
Zhongjie He ◽  
Yuanfu Xie ◽  
Wei Li ◽  
Dong Li ◽  
Guijun Han ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Three Dimensional ◽  
Ocean Model ◽  
Global Ocean ◽  
Background Error ◽  
Recursive Filters ◽  
Error Covariance ◽  
Observation Network ◽  
Isotropic Functions ◽  
Dependent Error

Abstract A recursive filter or parameterized curve fitting technique is usually used in a three-dimensional variational data assimilation (3DVAR) scheme to approximate the background error covariance, which can only represent the errors of an ocean field over a predetermined scale. Without an accurate flow-dependent error covariance that is also local and time dependent, a 3DVAR system may not provide good analyses because it is optimal only under the assumption of an accurate covariance. In this study, a sequential 3DVAR (S3DVAR) is formulated in model grid space to examine if there is useful information that can be extracted from the observation. This formulation is composed of a series of 3DVARs, each of which uses recursive filters with different length scales. It can provide an inhomogeneous and anisotropic analysis for the wavelengths that can be resolved by the observation network, just as with the conventional Barnes analysis or successive corrections. Being a variational formulation, S3DVAR can deal with data globally with an explicit specification of the observation errors; explicit physical balances or constraints; and advanced datasets, such as satellite and radar. Even though the S3DVAR analysis can be viewed as a set of isotropic functions superpositioned together, this superposition is not prespecified as in a single 3DVAR approach but is determined by the information that can be resolved by observation. The S3DVAR is adopted in a global sea surface temperature (SST) data assimilation system, into which the shipboard SSTs and the 4-km Advanced Very High Resolution Radiometer (AVHRR) Pathfinder daily SSTs are assimilated, respectively. The results demonstrate that the proposed S3DVAR works better in practice than a single 3DVAR.

scholarly journals A Discussion of Flow Pathways in the Central and Eastern Equatorial Pacific

2007 ◽  
Vol 37 (5) ◽  
pp. 1321-1339 ◽  
Author(s):  
Jaclyn N. Brown ◽  
J. Stuart Godfrey ◽  
Andreas Schiller
Keyword(s):  
Three Dimensional ◽  
Meridional Flow ◽  
Ocean Model ◽  
Equatorial Pacific ◽  
Global Ocean ◽  
Equatorial Pacific Ocean ◽  
Central Pacific ◽  
Equatorial Undercurrent ◽  
Eastern Equatorial Pacific ◽  
Southward Flow

Abstract An eddy-permitting global ocean model is used to interpret kinematics within the central and eastern equatorial Pacific Ocean, from 160°E to the coast of America. Because of high levels of variability in this region, observational studies of meridional flow are contradictory, in particular as to whether the net flow is northward or southward. Unlike most oceanographic datasets, model output can be analyzed at high temporal and spatial resolution, providing clues as to real ocean behavior. In the model, a net southward flow occurs across the equator east of 160°W, at most density layers throughout the year. In the central Pacific, from 160°E to 160°W, the net flow is northward but varies with season and occurs primarily in the mixed layer. This is a key region for the flow of Equatorial Undercurrent water into the Northern Hemisphere. The three-dimensional flow is very complex and seasonally dependent. It is vital that these flows are analyzed in an isopycnal framework, or else the pathways are very misleading. In the first half of the year, evidence is found of meridional tropical cells on either side of the equator out to ±5°. These cells appear to exist without any need for diapycnal downwelling. In the second half of the year, when tropical instability waves are active, the cells are overlaid by a strong surface southward flow that appears to be a bolus-type transport. This transport is not apparent unless the flow is calculated in the aforementioned manner.

Sign in / Sign up

Export Citation Format

Share Document