Ocean Modeling Discussion

Bonjour I'd like to make two points: 1- OBCs are designed to handle both physical and numerical modes, and are probably more useful for the latter. This is probably why, in all our long-term simulations, Orlansky-type radiation conditions (in the active/passive approach) outperformed all others in ...

NEW_S_COORD in CROCO corresponds to Vstretching=4 in ROMS/COAWST (first introduced in ROMS-UCLA in 2010)

Hi Kate, note that nonbreaking-wave-induced mixing and Langmuir turbulence are generally considered two different processes of wave-induced mixing (related to Stokes drift)... Patrick

For wave‐induced vertical mixing in KPP, see Wang et al., JGR 2010, based on Qiao et al, JPO 2004. It is now part of CROCO (ROMS_AGRIF)

a square vortex is possible, but you need some resonant vortex Rossby waves. See this plot by Schubert et al. (1999). I also heard that G. Roullet (LPO, France) has presented some results at the Ocean Sciences meeting where he could make a square vortex using some flux-corrected advection schemes ...

just a precision. ROMS_AGRIF also uses a full stencil at the interface (nesting with 1:1 gives the same results as no nesting at all). The model runs stably with 1:5 ratio, which gives excellent results in 2-way nesting (1:3 is preferable for 1-way nesting, because the solutions are naturally less ...

Hi, please use the ROMS-AGRIF forum for your problem ... Patrick

yes Kate, we have done the TANK test case in the homogeneous and two-layered fluid (internal soliton) using a non-hydrostatic version of ROMS_AGRIF. We can accurately reproduce both the hydrostatic and non-hydrostatic analytical solutions in the homogeneous case and lab experiments in the two-layer ...

Couvelard X., P. Marchesiello, L. Gourdeau, and J. Lefevre, 2008: barotropic zonal jets induced by islands in the southwest Pacific. Journal of Physical Oceanography, 38, 2185-2204.

The implicit correction of Lemarié et al. (2012) fixes the problem for us (in ROMS_AGRIF). We implemented it for both interior diffusion (bi-laplacian) and sponges (laplacian) and WET_DRY runs without any problem in all configurations (e.g., with wetting-drying cells in sponge areas).

See answer and bug fix report in ROMS_AGRIF forum:
https://gforge.inria.fr/forum/?group_id=735

Patrick

Hi Hernan, could that explain the "inconsistency" between surface bulk formulations and OBCs in the simulations that you presented in Rio last year?

Since the response is slow to come, I will give my understanding of the status of RSUP3. The RSUP3 scheme presented in Marchesiello et al. (2009) was first implemented in the ROMS_AGRIF version and we had some success with it on various applications. Then, a form of it was implemented in the Rutgers ...

I think that this discussion demonstrates the fact that users should not have to choose their combination of OBCs (unless they really want to). in the ROMS_AGRIF version, there is a default set of choices which avoids a lot of trouble for users and a much faster start up. concerning 2D radiative ...

Hi Sasha, Thanks for the details on the radiative heating choices. I understand the issue of Bflux changing sign with depth and how it may affect the physical consistency of nonlocal mixing. This is a good point that leaves us with interesting physical issues. Note that we are well aware of the "bug ...

Hi Sasha, In your formulation you use : NonLocalFlux = C * G(sigma) * SurfaceForcingFlux taking: SurfaceForcingFlux = stflx(i,j,itemp) - srflx(i,j) But in Large et al. (1994) SurfaceForcingFlux also contains the radiative heat absorbed in the boundary layer (at level sigma) as it was believed to ...

Hi John, make_tides now reads TPXO7 but we will look at your routines. The management and corrections of tidal phase and amplitude needed in the case of real time forcing is not straightforward. If you simplified some of the treatment processes, that would be interesting to us as well. We may want ...

For information, the romstools package (provided with the agrif version of roms) also has a tidal toolbox (in matlab) that processes TPXO for ROMS. It is called make_tides ...

Did you try and reduce the hyperviscosity coefficient? the rotation of biharmonic tensor induces large vertical fluxes that violate stability constraints (see Marchesiello et al. 2009). Clipping of hyperviscosity is needed in this case ...

the circulation is not that affected by local extrema (unless out of control) but is greatly affected by diapycnal mixing.

a discussion on the need for monotonicity is good of course ...

monotonocity is far from being the only issue with tracer advection. An example of lock exchange experiment in different models is given by Flavien Gouillon (PhD thesis) at http://coaps.fsu.edu/~gouillon/Spurious.html again, monotone schemes have implicit diffusion, which becomes a problem with ...

The scheme in Marchesiello et al (2009), let's call it RSUP3, is not meant to outperform UP3 (the standard ROMS upstream-biased advection scheme) in terms of numerical properties (accuracy, dispersion ...). It is only an attempt to correct excess diapycnal mixing that arises with steep slopes (even ...

I did not have much success with the Akima advection scheme. I think that the only progress from the scheme proposed in Marchesiello et al. (2009) is coming from Lemarié et al. (a paper that will soon be published). It is a significant update from my work that will allow isopycnal mixing (with no ...

We have also recently proposed a nowcast/forecast system over New Caledonia: http://prevision.ird.nc/ (look at PREVISIONS/OCEAN). It is based on a protable package developped as part of the Romstools (IRD team). Our New Caledonia system is presented in the July 2008 MERCATOR Newsletter n°30: http: ...

A 1-year postdoctoral position in regional modeling is available in the oceanographic lab of the IRD center of New Caledonia. The funding project is an integrated study of the relation between ecological conditions and tuna fisheries with a focus on regional ENSO and climate impacts. The person ...

Hi, I would like to report a problem with ROMS 3rd order "horizontal" advection scheme for tracer advection. This scheme is a very nice compromise between quality (no dispersion, quasi-monotonic) and CPU cost (see Shchepetkin, 1998). However, when applied to sigma coordinate models the issue of the ...