1. What graphics package is used to generate the plots of the WRFSI static fields?
2. What is NCL?
3. What do I need to do to have the GUI run NCL?
4. Is it necessary to use the GUI to run NCL?
5. Why don't the land/water boundaries match the map outline in the c-stagger grid average elevation plot?
6. Where can I find high resolution coastline data?
7. Why would a particular plot be missing?
8. Why are the bodies of water colored black on the soil temperature plot?
9. What version of NCAR Graphics and NCL can I use with the WRFSI GUI?

What graphics package is used to generate the plots of the WRFSI static fields?

The NCAR Command Language (NCL).

What is NCL?

NCAR Graphics Command Language is a programming language designed specifically for the analysis and visualization of data.

You can get more information about NCL at http://ngwww.ucar.edu.

What do I need to do to have the GUI run NCL?

You must have NCAR Graphics version 4.1.1, or higher, installed and its two environment variables set to create graphic plots. The env variables are NCARG_ROOT and NCL_COMMAND. For exampe, set the following:

setenv NCARG_ROOT /usr/local/ncarg-4.3.0
setenv NCL_COMMAND /usr/local/ncarg-4.3.0/bin/ncl   (must include ncl)
setenv NCARG_RANGS /data/ncl/rangs   (optional high resolution coastline data)

If the first two NCAR Graphics env variables are not defined, the GUI will supress the Domain Graphics user interface option.

Is it necessary to use the GUI to run NCL?

No, but you must have NCAR Graphics version 4.1.1, or higher, installed and its two environment variables set. To create graphics plots of the WRFSI static fields outside of the GUI, just run the perl script INSTALLROOT/graphica/ncl/generate_images.pl. For example:

cd INSTALLROOT/graphics/ncl
setenv MOAD_DATAROOT /wrfsi/domains/japan
generate_images.pl

Or,

cd INSTALLROOT/graphics/ncl
generate_images.pl -domain=/wrfsi/domains/japan

Additional usage information for generate_images.pl.

Why don't the land/water boundaries match the map outline in the c-stagger grid average elevation plot?

NCL has the ability to use a multi-resolution coastline database called RANGS (Regionally Accessible Nested Global Shorelines) developed by Rainer Feistel from Wessel and Smith's GSHHS (Global Self-consistent Hierarchical High-resolution Shoreline) database.

Unfortunately, NCL does not yet have the ability to do land/water masking when using this database. Thus, a "best guess" is made for this boundary, using the maximum and minimum average elevation values and the domain size.

Where can I find high resolution coastline data?

RANGS (Regionally Accessible Nested Global Shorelines) show high-resolution coastlines. http://ngwww.ucar.edu/ncl-talk/2002/0015.html

Why would a particular plot be missing?

Generally, eight plots are created with each domain:
c-stagger grid average elevation (avc),
annual minimum greenness fraction (gnn),
annual maximum greenness fraction (gnx),
bottom layer (30-90 cm) dominant category soiltype (sbl),
top layer (0-30 cm) dominant category soiltype (stl),
terrain slope index (slp),
terrain adjusted mean annual soil temperature (tmp), and
land use dominant category (use).

Two additional plots are available as of WRFSI version 2.0. They are:

maximun snow albedo (alb), and
maximun snow albedo interpolated (albint).

Occasionally, one of these plots may be missing. This is due to a plotting error that has occurred during the plotting process, and can happen when large domains with fine resolution are created.

Plots of domains located exclusively over an ocean can cause problems for the use of the NCL software, at this time.

Why are the bodies of water colored black on the soil temperature plot?

The soil temperature data include only soil temperature data, and those grid points located entirely over bodies of water are assigned the missing data parameter, which is plotted as black.

What version of NCAR Graphics and NCL can I use with the WRFSI GUI?

We have determined that, for best results, the version of NCAR Graphics that you use should match the version you use for NCAR Graphics NCL. For example, if you are using NCARG v4.1.1 then you should be using NCL v4.1.1 as well.

Any combination of NCARG and NCL versions (with and without the RANGS database) will produce gmeta graphics output by running the script, generate_images.pl. In some cases, there may be no background map. In order to get the high resolution background maps of coastline areas you absolutely must have RANGS database. If the domain is fully within the continental US, having RANGS will make no difference. RANGS is a coastline data set.

You may get error messages from the script, but the images will be created anyway.

Here is a breakdown of test results: 



NCARG version	NCL version	RANGS (y/n)	Map Result?
4.1.1	4.1.1	n	Low res
4.2.1	4.1.1	n	US map only
4.2.2	4.1.1	n	US map only
4.3.0	4.1.1	n	Low res
4.1.1	4.3.0	n	No map
4.2.1	4.3.0	n	US map only
4.2.2	4.3.0	n	US map only
4.3.0	4.3.0	n	US map only
4.1.1	4.1.1	y	Low res
4.2.1	4.1.1	y	US map only
4.2.2	4.1.1	y	US map only
4.3.0	4.1.1	y	Low res
4.1.1	4.3.0	y	High res, no US map
4.2.1	4.3.0	y	High res
4.2.2	4.3.0	y	High res
4.3.0	4.3.0	y	High res

WRFSI GUI version 2.0.0 mandated, within the software, that the user needs NCL and NCARG ver 4.3, but this is too restrictive. It looks like instead of requiring the you to have NCARG 4.3.0, you can get good results as long as you have a version higher than 4.1.1 and download the RANGS database. If you don't have a NCARG higher than 4.1.1, then you'll get the best results using NCL version 4.1.1.


If your code is too restrictive and needs to be changed, edit line 613, in SOURCE_ROOT/wrfsi/etc/generate_images.pl.in, line 613, in INSTALLROOT/wrfsi/etc/generate_images.pl, and line 613, in INSTALLROOT/wrfsi/graphics/ncl/generate_images.pl


from
  my $lowestversion="430";


to
  my $lowestversion="411";

Last updated: Fri 26 Nov 2004