On reducing the slope parameter in terrain-following numerical ocean models

Martinho, Antonio S.; Batteen, Mary L.

doi:10.1016/j.ocemod.2006.01.003

Cited by 35 publications

(30 citation statements)

References 11 publications

(6 reference statements)

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“…Another processoriented study was conducted by Batteen et al (2007) in the same area with a terrain-following, 3 km-resolution model. Filament structures were obtained off Cape Ghir when an iterative topography developed by Martinho and Batteen (2006) was used, while the Gaussian smoothed topography only generated little mesoscale activity.…”

Section: Introductionmentioning

confidence: 99%

Generation of the Cape Ghir upwelling filament: A numerical study

et al. 2012

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Filaments are narrow, shallow structures of cool water originating from the coast. They are typical features of the four main eastern boundary upwelling systems (EBUS). In spite of their significant biological and chemical roles, through the offshore exportation of nutrient-rich waters, the physical processes that generate them are still not completely understood. This paper is a process-oriented study of filament generation mechanisms. Our goal is twofold: firstly, to obtain a numerical solution able to correctly represent the characteristics of the filament off Cape Ghir (30• 38'N, northwest Africa) in the Canary EBUS and secondly, to explain its formation by a simple mechanism based on the balance of potential vorticity.The first goal is achieved by the use of the ROMS model (Regional Ocean Modeling System) with embedded domains around Cape Ghir, with a horizontal resolution going up to 1.5 km for the finest domain. The latter gets its initial and boundary conditions from a parent solution and is forced by climatological, high-resolution atmospheric fields. The modeled filaments display spatial, temporal and physical characteristics in agreement with the available in situ and satellite observations. This model solution is used as a reference to compare the results with a set of process-oriented experiments. These experiments allow us to reach the second objective. The solutions serve to highlight the contributions of various processes to the filament generation. Since the study is focused on general processes present under climatological forcing conditions, inter-annual forcing is not necessary.The underlying idea for the filament generation is the balance of potential vorticity in the Canary EBUS: the upwelling jet is characterized by negative relative vorticity and flows southward along a narrow band of uniform potential vorticity. In the vicinity of the cape, an injection of relative vorticity induced by the wind breaks the existing vorticity balance. The upwelling jet is prevented from continuing its way southward and has to turn offshore to follow lines of equal potential vorticity.The model results highlight the essential role of wind, associated with the particular topography (coastline and bottom) around the cape. The mechanism presented here is general and thus can be applied to other EBUS.

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Section: Introductionmentioning

confidence: 99%

Generation of the Cape Ghir upwelling filament: A numerical study

et al. 2012

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“…Since the lack of eddy separation off Cabo de Sao Vicente is a consequence of a numerical choice, i.e., in this case, bathymetry smoothing, an alternative type of smoothing the topography, called a one-dimensional direct iterative method (Martinho and Batteen, 2006) is now applied to the NCCS. A comparison by Martinho and Batteen (2006) of the traditional 2D smoothing with Gaussian filters (as used in Experiments 2 and 3) (Fig.…”

Section: Results Of Experiments 4 -Iterative Topography Experimentsmentioning

confidence: 99%

“…A comparison by Martinho and Batteen (2006) of the traditional 2D smoothing with Gaussian filters (as used in Experiments 2 and 3) (Fig. 10b) with this alternative method (Fig.…”

Section: Results Of Experiments 4 -Iterative Topography Experimentsmentioning

confidence: 99%

“…Based on these results, a new type of smoothing the topography recently developed by Martinho and Batteen (2006), which better preserves the raw topography, was subsequently shown in Experiment 4 to produce the anticyclonic meander off Cabo de Sao Vicente. This choice was then used in the final and most realistic of the NCCS experiments, Experiment 5, in which a seasonal study was conducted from March to September 1996.…”

Section: Discussionmentioning

confidence: 98%

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A process-oriented modelling study of the coastal Canary and Iberian Current system

et al. 2007

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“…A new topography smoothing technique (Martinho and Batteen, 2006) was used, which preserves the original configuration of the coastline, continental shelf break, seamounts, and islands, while still reducing the slope parameter to an acceptable value at all grid points. According to Mellor et al (1998), the slope parameter must be less than 0.2 at all locations in order to decrease the pressure gradient force error to an acceptable error (i.e., $0.5 cm s À1 ).…”

Section: Data Setsmentioning

confidence: 99%