Pressure gradient documentation conundrum and a request

Discussions, suggestions and corrections to ROMS/TOMS documentation currently under developement.

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rduran
Posts: 139
Joined: Fri Jan 08, 2010 7:22 pm
Location: Theiss Research

Pressure gradient documentation conundrum and a request

#1 Post by rduran » Tue Nov 08, 2011 4:10 pm

In the current cppdefs ( svn $Id: cppdefs.h 572 2011-10-18 17:56:01Z arango $ ) the pressure gradient options are:

Code: Select all

** Pressure gradient algorithm OPTIONS:                                      **
**                                                                           **
**   If no option is selected, the pressure gradient term is computed using  **
**   standard density Jacobian algorithm. Notice that there are two quartic  **
**   pressure Jacobian options. They differ on how the WENO reconciliation   **
**   step is done and in the monotonicity constraining algorithms.           **
**                                                                           **
** DJ_GRADPS           use if splines density Jacobian (Shchepetkin, 2000)   **
** PJ_GRADP            use if finite volume Pressure Jacobian (Lin,1997)     **
** PJ_GRADPQ2          use if quartic 2 Pressure Jacobian (Shchepetkin,2000) **
** PJ_GRADPQ4          use if quartic 4 Pressure Jacobian (Shchepetkin,2000) **
** WJ_GRADP            use if weighted density Jacobian (Song,1998)          **
In a 2002 paper (Developments in terrain-following ocean models:
intercomparisons of numerical aspects - Ezer, Arango & Shchepetkin) it is shown that ROMS can have an order of magnitude bigger errors than POM (best algorithm vs best algorithm when topography is very steep). In this paper they cite a paper titled A method for computing horizontal pressure-gradient force in an oceanic model with a nonaligned vertical coordinate (which was actually published in 2003 - Shchepetkin & McWilliam).

There is no Shchepetkin 2000 in the bibliography (https://www.myroms.org/wiki/index.php/Bibliography) so I'm wondering if the pressure gradient options in cppdefs.h are the same as the ones described in the 2003 paper.

It seems however that the 2003 paper algorithm was never fully implemented in ROMS-Rutgers
(viewtopic.php?f=14&t=2437&p=9083&hilit= ... ient#p9083)

Are there any plans to implement the 2003 pressure gradient algorithm in ROMS-rutgers?

Is it possible to use the latest pressure gradient algorithms? Are there newer algorithms I am missing?

Or are there any plans for future releases of algorithms that would improve ROMS performance over very steep topography?

Attempts to simulate a realistic continental slope would benefit from these improvements, unfortunately however I am probably not in a position to contribute to this endeavor myself.

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shchepet
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Re: Pressure gradient documentation conundrum and a request

#2 Post by shchepet » Wed Nov 09, 2011 1:06 am

Shchepetkin, 2000 (also cited in Ezer, Arango, Shchepetkin, 2002) refers to
http://www.atmos.ucla.edu/~alex/ROMS/pgf1A.ps
http://www.atmos.ucla.edu/~alex/ROMS/pgf1B.ps
which are odd and even pages of the same document (these files are designed
to generate a two-sided printout using one-sided black-and-white printer). It was
never formally published, even though algorithms developed there are widely used.

rduran
Posts: 139
Joined: Fri Jan 08, 2010 7:22 pm
Location: Theiss Research

Re: Pressure gradient documentation conundrum and a request

#3 Post by rduran » Thu Nov 10, 2011 2:46 am

Thank you Alexander!

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