Ocean Modeling Discussion

ROMS/TOMS

Search for:
 It is currently Sat Jul 22, 2017 2:49 pm

 Page 1 of 1 [ 1 post ]
 All times are UTC
Author Message
 Post subject: Terrain-following vertical coordinate overhaulPosted: Fri Mar 06, 2009 4:23 am

Joined: Wed Feb 26, 2003 4:41 pm
Posts: 1008
Location: IMCS, Rutgers University
ROMS terrain-following, vertical coordinate have been revisited and further generalized to support additional transformation equations and numerous vertical stretching function provided that few constraints are satisfied. For more detailed information please check WikiROMS. Notice that this Vertical S-coordinate link provides technical information, rules to follow when creating additional vertical stretching functions, metadata considerations to facilitate post-processing, and few examples comparing the vertical transformations.

The new tranformation and vertical stretching functions are now available in ROMS svn revision 322 (see track ticket).

This implies that user need to be more careful from now on when preparing initial conditions, boundary conditions, climatologies, and observations since there are various ways to compute the depths of the grid in terms of the vertical transformations and their associated stretching parameters. A new routine netcdf_check_var was added to module mod_netcdf.F to check these parameters for consistency.

It is my plan to start releasing in the repository all the Matlab scripts that maybe used for pre- and post-processing. We need to guaranttee that users are using the official codes to compute the depths associated with a particular application. There are a lot of scripts that may not be doing this correctly. Anyway, it is a good idea to keep these scripts under svn control.

Warning:

• All the standard input scripts (ocean*.in) were changed to add two new parameters Vtransform and Vstretching:
Code:
! Set vertical, terrain-following coordinates transformation equation and
! stretching function (see below for details), [1:Ngrids].

Vtransform == 1                          ! transformation equation
Vstretching == 1                          ! stretching function

! Vertical S-coordinates parameters, [1:Ngrids].

THETA_S == 5.0d0                      ! surface stretching parameter
THETA_B == 0.4d0                      ! bottom  stretching parameter
TCLINE == 50.0d0                     ! critical depth (m)
Here, Vtransform = 1 correspond to the original vertical transformation in ROMS (available since 1999). Vstretching = 1 corresponds also to the origina vertical stretching function (Song and Haidvogel, 1994). The advantages of the new transformation and stretching functions are discussed in WikiROMS.

• In order to use the new transformation (Vtransform=2) and vertical stretching funtions (Vstretching=1,2,3) you need to regenerate your input netcdf files and provide the correct 3D fields that depend on the vertical grid (depths). Usually, such fields are interpolated to tthe terrain-following coordinate grid. Notice that in the idealized test problems, the 3D fields are automatically assigned at the correct depths and no changes are necessary when using analytical expressions.

• Notice that there are several possibilities for vertical stretching functions, Vstretching = 1,2,3. Functions 1 and 2 are appropriate for applications with depth bathymetry. I higlhly recommend to use function 3 in very shallow sediment applications (<200m). It is your resposability to choose the appropriate function for your application.

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 1 of 1 [ 1 post ]

 All times are UTC

Who is online

Users browsing this forum: Bing [Bot] and 1 guest

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum

Search for:
 Jump to:  Select a forum ------------------ News, Events & Job Opportunities    Meetings/Workshops    Job Opportunities    Ocean News ROMS/TOMS    ROMS Adjoint    ROMS Benchmarks    ROMS Bugs    ROMS Discussion    ROMS Documentation    ROMS Ecosystem    ROMS FAQ    ROMS Ice    ROMS Information    ROMS Installation    ROMS Known Problems    ROMS Messages    ROMS Problems    ROMS Releases    ROMS Results    ROMS Sediment    ROMS Source    ROMS Tips    ROMS Tools and Techniques    ROMS Trivia    ROMS Usage    ROMS Webinar    ROMS Wish List ROMS/TOMS Applications    User Applications    Adriatic Sea Ocean Modeling    Ocean Modeling FAQ