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Re: COHERENS sigma to meters z coordinate



Hi Francisco,
In the message from Paul Farrar
http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_2003/msg00039.html

he defines a variable we can use for ZAXREPLACE.  The
data Paul uses is in two x and y and your datasets are in one
or the other, but I think you can use the same ideas.  The data
set he uses is on-line.  I'll use that data for an example

yes? USE  "http://pdas.navo.navy.mil/cgi-bin/nph-nc/data/SWAFS/swafs_ame_gme_2003011500.nc"

yes? SHOW DATA
..
 name     title                  I      J       K       L
 GRID_WATER_DEP
          Grid Water Depth      1:126  1:101   ...     ...
 WATER_TEMP
          Water Temperature     1:126  1:101   1:46    1:24

 
yes? SHADE grid_water_dep
yes? SET REGION/L=1

 ! Put water depth onto a grid with a depth axis
 ! (Paul uses reshape; either way this depends on
 ! the fact that the variables share the same X-Y grid).

yes? LET bb = grid_water_dep + 0*water_temp[L=1]
yes? SHOW GRID bb

  ! Define zz as the depth on the sigma-layer axis;
  ! this is the function we need for the second
  ! argument to zaxreplace

yes? LET zz=z*bb
yes? STAT zz
yes? PLOT/I=12/J=40 zz  ! zz is linear, ranging 0 to depth

  ! Define an output Z axis in depth units,
  ! and a variable on that axis

yes? DEF AXIS/Z=0:5500:100/DEPTH z100
yes? LET znew = z[gz=z100]
 
!  New variable on the depth axis

yes? LET watertemp_depth = ZAXREPLACE(water_temp, zz, znew)

yes? SET VIEW left
yes? SHADE/L=1/Y=39/TITLE="water temp, sigma" water_temp
 
yes? SET VIEW right
yes? SHADE/L=1/Y=39N/TITLE="water temp, depth" watertemp_depth
 
 

Francisco J Campuzano Guillen wrote:

Hi Ansley:
        I have been trying with the ZAXREPLACE, and couldn't get the
conversion done. I'll give you a bit more of information about my
ouput files for a better understand of the problem. My output files are
this way:

 1> C:\TMAP\fer_dsets\data\frontA_1.out3U.cdf
 name     title                             I         J         K         L
 DEP      water_depth                      1:50      1:1       ...       ...
 U2       U3D                              1:50      1:1       1:20      1:13
 V2       V3D                              1:50      1:1       1:20      1:13
 W2PHYS   W3D                              1:50      1:1       1:20      1:13
 CONCN    Contaminant                      1:50      1:1       1:20      1:13

    2> C:\TMAP\fer_dsets\data\seichA_1.out3U.cdf
 name     title                             I         J         K         L
 DEP      water_depth                      1:1       1:60      ...       ...
 U2       U3D                              1:1       1:60      1:20      1:8
 V2       V3D                              1:1       1:60      1:20      1:8
 W2PHYS   W3D                              1:1       1:60      1:20      1:8
 S        Salinity                         1:1       1:60      1:20      1:8

where S or CONCN have 20 sigma layers, and DEP is the depth in meters
for every I or J step, being 50 and 60 values respectively. So I do not
have a proper function for transforming the sigma layer into meters.
How should I replace or transform the Z-axis?. Many thanks in advance
for your advice. Regards:

                                Francisco Javier Campuzano Guillen

On Thu, 16 Jan 2003 15:07:53 -0800 Ansley Manke <ansley@pmel.noaa.gov>
wrote:

> Hi Francisco,
> Welcome to Ferret!  There is a method to replace the Z axis
> and convert from sigma coordinates to depth.  There is an
> FAQ on this; the example there (using ZAXREPLACE) should
> help you, if you have a function that relates the sigma levels to
> depth in meters.
>
> http://ferret.pmel.noaa.gov/Ferret/FAQ/data_management/sigma_coordinate_demo.html
>
> Ansley Manke
>
>
>
>
> Francisco J Campuzano Guillen wrote:
>
> > Hello Ferret users:
> >
> > This is my first message to the list, I recently started to use this
> > software because of the need to represent the NETCDF results from the
> > COHERENS (Coupled Hydrodynamical-Ecological Model for Regional and
> > Shelf Seas) model.
> > At this moment, I'm starting to experiment with the test cases that
> > comes included in the CD-ROM, and trying to represent the same
> > diagrams as they did in the COHERENS User's Guide(where depths are
> > represented in meters),and here is where my doubt comes:
> > How can I represent with the FERRET package the vertical coordinate in
> > meters instead of sigma-coordinated (I'm using the version 5.41 for
> > win32 (so -gui mode is not supported))?.Although I can use the data in
> > the default sigma coordinates,the outcomes when I SET DATA are:
> >
> > *** NOTE: Units on axis "z" are not recognized: sigma_level
> > *** NOTE: They will not be convertible
> >
> > I know it is possibly a quite simple question, but I have been looking
> > through the FERRET USERGUIDE and couldn't find the solution, if you
> > need any other details please ask.Thank you very much in advance your
> > help.Yours sincerely:
> >
> >                         Francisco Javier Campuzano Guillin
> >
> > ----------------------------------------
> > Francisco J Campuzano Guillin
> > Email: G.F.Campuzano@hull.ac.uk
> > University of Hull
>
> --
> Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246
>
>

----------------------------------------
Francisco J Campuzano Guillén
Email: G.F.Campuzano@hull.ac.uk
University of Hull

--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246
 


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