On Mon, 2 Nov 2009, Kyle Shannon wrote:
Hello everyone,
I am trying to use the netCDF subset tools and I was wondering what values are
acceptable for the 'vertCoord'
variable. Can I specify height above ground level and set vertCoord to n
meters above the ground?
Hiya Kyle,
I'm not quite sure I understand your question but the netCDF subset tool
can only return values that are in the file. For instance, if the file
has 2 meter height above ground level, you can not request 5 meters above
ground.
Here's a sample url DGEX_Alaska_12km grid
http://motherlode.ucar.edu:8081/thredds/ncss/grid/fmrc/NCEP/DGEX/Alaska_12km/files/DGEX_Alaska_12km_20091101_1200.grib2/dataset.html
Looking at the page, you can see that the values that are acceptable are
the values next to variable Geopotential_height.
with Vertical Levels (pressure) : 100000.0 85000.0 70000.0 50000.0 25000.0 Pa
Geopotential_height
Documentation about vertical coordinates says:
For Grid as Point only , you may specify the vertical coordinate. The
vertical slice closest to the requested coordinate will be returned. The
possible vertical coordinates are shown in the Dataset Descriptor
document. If you specify multiple variables with different vertical
coordinates, ambiguous results are possible, and you are advised not to
use the service in this way. If you do, the following rules are used:
1. Variables are examined in order they appear in the query, and the
vertical coordinate for the first variable that has one is used.
2. The service loops through the levels of that vertical coordinate,
and for each variable looks for the closest value (ignoring units!!)
3. If the value is outside the range for that variable, a missing value
(NaN) is used.
Example:
* vertCoord=850
For more information:
http://www.unidata.ucar.edu/projects/THREDDS/tech/interfaceSpec/NetcdfSubsetService.html
Robb...
>
# ===================
Kyle Shannon
Physical Science Technician
RMRS Fire Sciences Lab
Fire, Fuels & Smoke - RWU 4405
5775 Highway 10 W.
Missoula, MT 59808
(406)646-6577
kshannon@xxxxxxxxx
ksshannon@xxxxxxxxx
# ===================
===============================================================================
Robb Kambic Unidata Program Center
Software Engineer III Univ. Corp for Atmospheric Research
rkambic@xxxxxxxxxxxxxxxx WWW: http://www.unidata.ucar.edu/
===============================================================================
