Global ocean modeling and rendering techniques based on ellipsoid Rectangular grid mapping

Abstract. In this article we propose two grid generation methods for global ocean general circulation models. Contrary to conventional dipolar or tripolar grids, the proposed methods are based on Schwarz–Christoffel conformal mappings that map areas with user-prescribed, irregular boundaries to those with regular boundaries (i.e., disks, slits, etc.). The first method aims at improving existing dipolar grids. Compared with existing grids, the sample grid achieves a better trade-off between the enlargement of the latitudinal–longitudinal portion and the overall smooth grid cell size transition. The second method addresses more modern and advanced grid design requirements arising from high-resolution and multi-scale ocean modeling. The generated grids could potentially achieve the alignment of grid lines to the large-scale coastlines, enhanced spatial resolution in coastal regions, and easier computational load balance. Since the grids are orthogonal curvilinear, they can be easily utilized by the majority of ocean general circulation models that are based on finite difference and require grid orthogonality. The proposed grid generation algorithms can also be applied to the grid generation for regional ocean modeling where complex land–sea distribution is present.

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The Dependence of Global Ocean Modeling on Background Diapycnal Mixing

The Scientific World JOURNAL ◽

10.1155/2014/838701 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7

Author(s):

Zengan Deng

Keyword(s):

Surface Temperature ◽

Cold Water ◽

Ocean Model ◽

Meridional Overturning Circulation ◽

Ocean Modeling ◽

Global Ocean ◽

Diapycnal Mixing ◽

Hybrid Coordinate Ocean Model ◽

Order Of Magnitude ◽

Meridional Overturning

The Argo-derived background diapycnal mixing (BDM) proposed by Deng et al. (in publish) is introduced to and applied in Hybrid Coordinate Ocean Model (HYCOM). Sensitive experiments are carried out using HYCOM to detect the responses of ocean surface temperature and Meridional Overturning Circulation (MOC) to BDM in a global context. Preliminary results show that utilizing a constant BDM, with the same order of magnitude as the realistic one, may cause significant deviation in temperature and MOC. It is found that the dependence of surface temperature and MOC on BDM is prominent. Surface temperature is decreased with the increase of BDM, because diapycnal mixing can promote the deep cold water return to the upper ocean. Comparing to the control run, more striking MOC changes can be caused by the larger variation in BDM.

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Wave effects in global ocean modeling: parametrizations vs. forcing from a wave model

Ocean Dynamics ◽

10.1007/s10236-018-1220-2 ◽

2018 ◽

Vol 68 (12) ◽

pp. 1739-1758 ◽

Cited By ~ 9

Author(s):

Stéphane Law Chune ◽

Lotfi Aouf

Keyword(s):

Wave Model ◽

Ocean Modeling ◽

Global Ocean ◽

Wave Effects

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An Assessment of Orthobaric Density in the Global Ocean

Journal of Physical Oceanography ◽

10.1175/jpo2796.1 ◽

2005 ◽

Vol 35 (11) ◽

pp. 2054-2075 ◽

Cited By ~ 31

Author(s):

Trevor J. McDougall ◽

David R. Jackett

Keyword(s):

Southern Hemisphere ◽

World Ocean ◽

Ocean Basin ◽

Ocean Modeling ◽

Global Ocean ◽

Potential Density ◽

Vertical Coordinate ◽

The World ◽

Density Surface

Abstract Orthobaric density has recently been advanced as a new density variable for displaying ocean data and as a coordinate for ocean modeling. Here the extent to which orthobaric density surfaces are neutral is quantified and it is found that orthobaric density surfaces are less neutral in the World Ocean than are potential density surfaces referenced to 2000 dbar. Another property that is important for a vertical coordinate of a layered model is the quasi-material nature of the coordinate and it is shown that orthobaric density surfaces are significantly non-quasi-material. These limitations of orthobaric density arise because of its inability to accurately accommodate differences between water masses at fixed values of pressure and in situ density such as occur between the Northern and Southern Hemisphere portions of the World Ocean. It is shown that special forms of orthobaric density can be quite accurate if they are formed for an individual ocean basin and used only in that basin. While orthobaric density can be made to be approximately neutral in a single ocean basin, this is not possible in both the Northern and Southern Hemisphere portions of the Atlantic Ocean. While the helical nature of neutral trajectories (equivalently, the ill-defined nature of neutral surfaces) limits the neutrality of all types of density surface, the inability of orthobaric density surfaces to accurately accommodate more than one ocean basin is a much greater limitation.

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A multi-resolution approach to global ocean modeling

Ocean Modelling ◽

10.1016/j.ocemod.2013.04.010 ◽

2013 ◽

Vol 69 ◽

pp. 211-232 ◽

Cited By ~ 149

Author(s):

Todd Ringler ◽

Mark Petersen ◽

Robert L. Higdon ◽

Doug Jacobsen ◽

Philip W. Jones ◽

...

Keyword(s):

Ocean Modeling ◽

Global Ocean

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Ocean modeling in a global ocean observing system

Reviews of Geophysics ◽

10.1029/93rg00134 ◽

1993 ◽

Vol 31 (3) ◽

pp. 281 ◽

Cited By ~ 14

Author(s):

Neville R. Smith

Keyword(s):

Ocean Modeling ◽

Global Ocean ◽

Ocean Observing

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On the use of Schwarz–Christoffel conformal mappings to the grid generation for global ocean models

Geoscientific Model Development Discussions ◽

10.5194/gmdd-8-1337-2015 ◽

2015 ◽

Vol 8 (2) ◽

pp. 1337-1373

Author(s):

S. Xu ◽

B. Wang ◽

J. Liu

Keyword(s):

Conformal Mapping ◽

General Circulation ◽

Grid Generation ◽

General Circulation Models ◽

Ocean Modeling ◽

Global Ocean ◽

Generation Task ◽

Grid Design ◽

Ocean Models ◽

New Algorithms

Abstract. In this article we propose two conformal mapping based grid generation algorithms for global ocean general circulation models (OGCMs). Contrary to conventional, analytical forms based dipolar or tripolar grids, the new algorithms are based on Schwarz–Christoffel (SC) conformal mapping with prescribed boundary information. While dealing with the basic grid design problem of pole relocation, these new algorithms also address more advanced issues such as smoothed scaling factor, or the new requirements on OGCM grids arisen from the recent trend of high-resolution and multi-scale modeling. The proposed grid generation algorithm could potentially achieve the alignment of grid lines to coastlines, enhanced spatial resolution in coastal regions, and easier computational load balance. Since the generated grids are still orthogonal curvilinear, they can be readily utilized in existing Bryan–Cox–Semtner type ocean models. The proposed methodology can also be applied to the grid generation task for regional ocean modeling where complex land–ocean distribution is present.

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A Deep Learning Model for Forecasting Velocity Structures of the Loop Current System in the Gulf of Mexico

Forecasting ◽

10.3390/forecast3040056 ◽

2021 ◽

Vol 3 (4) ◽

pp. 934-953

Author(s):

Ali Muhamed Ali ◽

Hanqi Zhuang ◽

James VanZwieten ◽

Ali K. Ibrahim ◽

Laurent Chérubin

Keyword(s):

Deep Learning ◽

Gulf Of Mexico ◽

Short Term Memory ◽

Numerical Models ◽

Current System ◽

Ocean Modeling ◽

Global Ocean ◽

Ocean Current ◽

Loop Current

Despite the large efforts made by the ocean modeling community, such as the GODAE (Global Ocean Data Assimilation Experiment), which started in 1997 and was renamed as OceanPredict in 2019, the prediction of ocean currents has remained a challenge until the present day—particularly in ocean regions that are characterized by rapid changes in their circulation due to changes in atmospheric forcing or due to the release of available potential energy through the development of instabilities. Ocean numerical models’ useful forecast window is no longer than two days over a given area with the best initialization possible. Predictions quickly diverge from the observational field throughout the water and become unreliable, despite the fact that they can simulate the observed dynamics through other variables such as temperature, salinity and sea surface height. Numerical methods such as harmonic analysis are used to predict both short- and long-term tidal currents with significant accuracy. However, they are limited to the areas where the tide was measured. In this study, a new approach to ocean current prediction based on deep learning is proposed. This method is evaluated on the measured energetic currents of the Gulf of Mexico circulation dominated by the Loop Current (LC) at multiple spatial and temporal scales. The approach taken herein consists of dividing the velocity tensor into planes perpendicular to each of the three Cartesian coordinate system directions. A Long Short-Term Memory Recurrent Neural Network, which is best suited to handling long-term dependencies in the data, was thus used to predict the evolution of the velocity field in each plane, along each of the three directions. The predicted tensors, made of the planes perpendicular to each Cartesian direction, revealed that the model’s prediction skills were best for the flow field in the planes perpendicular to the direction of prediction. Furthermore, the fusion of all three predicted tensors significantly increased the overall skills of the flow prediction over the individual model’s predictions. The useful forecast period of this new model was greater than 4 days with a root mean square error less than 0.05 cm·s−1 and a correlation coefficient of 0.6.

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1/32° global ocean modeling and prediction

2003 User Group Conference. Proceedings ◽

10.1109/dodugc.2003.1253406 ◽

2004 ◽

Author(s):

J.F. Shriver ◽

H.E. Hurlburt ◽

A.J. Wallcraft ◽

R.C. Rhodes ◽

O.M. Smedstad

Keyword(s):

Ocean Modeling ◽

Global Ocean ◽

Modeling And Prediction

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100 Years of Progress in Ocean Observing Systems

Meteorological Monographs ◽

10.1175/amsmonographs-d-18-0014.1 ◽

2019 ◽

Vol 59 ◽

pp. 3.1-3.46 ◽

Cited By ~ 1

Author(s):

Russ E. Davis ◽

Lynne D. Talley ◽

Dean Roemmich ◽

W. Brechner Owens ◽

Daniel L. Rudnick ◽

...

Keyword(s):

Ocean Circulation ◽

Large Scale ◽

Southern Oscillation ◽

World Ocean ◽

Ocean Modeling ◽

Ocean Dynamics ◽

Global Ocean ◽

Tropical Ocean ◽

New Instrument ◽

Observing Systems

Abstract The history of over 100 years of observing the ocean is reviewed. The evolution of particular classes of ocean measurements (e.g., shipboard hydrography, moorings, and drifting floats) are summarized along with some of the discoveries and dynamical understanding they made possible. By the 1970s, isolated and “expedition” observational approaches were evolving into experimental campaigns that covered large ocean areas and addressed multiscale phenomena using diverse instrumental suites and associated modeling and analysis teams. The Mid-Ocean Dynamics Experiment (MODE) addressed mesoscale “eddies” and their interaction with larger-scale currents using new ocean modeling and experiment design techniques and a suite of developing observational methods. Following MODE, new instrument networks were established to study processes that dominated ocean behavior in different regions. The Tropical Ocean Global Atmosphere program gathered multiyear time series in the tropical Pacific to understand, and eventually predict, evolution of coupled ocean–atmosphere phenomena like El Niño–Southern Oscillation (ENSO). The World Ocean Circulation Experiment (WOCE) sought to quantify ocean transport throughout the global ocean using temperature, salinity, and other tracer measurements along with fewer direct velocity measurements with floats and moorings. Western and eastern boundary currents attracted comprehensive measurements, and various coastal regions, each with its unique scientific and societally important phenomena, became home to regional observing systems. Today, the trend toward networked observing arrays of many instrument types continues to be a productive way to understand and predict large-scale ocean phenomena.

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