On 03/02/2011 09:24 PM, Bryn Jones wrote:
Greetings.
I was wondering what the limits are, if any, for the thickness of
concrete road beds in METRo.
We were using a value of 0.3018 m which worked but a shallower 0.3017
m did not work and METRo choked. Somewhere in between there seems to
be an allowable threshold. Is this correct? If so, ~1 foot of
concrete as a minimum seems awfully thick.
Do any of the other road bed materials (sand, asphalt and crushed
rock) have maximum and/or minimum allowable thicknesses?
Thanks.
**S. Bryn Jones**
Content Development Meteorologist
Content Division
Pelmorex - The Weather Network
Tel.: (905) 829-1159 ext.1401
[email protected] <mailto:[email protected]>
Hi Bryn,
If you look at the documentation for the station configuration file
(http://documentation.wikia.com/wiki/Input_station_%28METRo%29), you
will find the following paragraph:
*Warning*: Under particular condition, METRo will not be able to run
with a given configuration. You will then see an error containing the
string "/Numerical stability test failed/". See the first bullet of the
changelog of version 3.0.1
<http://documentation.wikia.com/wiki/Changelog_%28METRo%29#Changes_7>
for more information.
The first bullet is :
* Stability check for the CFL condition
<http://en.wikipedia.org/wiki/Courant%E2%80%93Friedrichs%E2%80%93Lewy_condition>
in file |grille.f|. See https://gna.org/bugs/?7737
The CFL condition is well know in the Numerical Weather Prediction
world. In METRo, this condition implies that, for numerical stability
reasons, a given layer can not be less than a certain thickness. The
thickness depends of the layer's type.
In the next METRo version, to be released this summer, you will be able
to define you own layer types. Thus, you will be able to fine tune the
station configuration by using the physical parameters (conductivity and
capacity) of your layer.
But before that, you will have to play with the layer thickness. Using
another type might also works and gives better results.
Hope this answers your question,
Miguel
--
Miguel Tremblay
Coordonnateur national des services commerciaux de données-
National coordinator, commercial data services
Centre météorologique canadien - Canadian meteorological centre (CMC)
Environnement Canada - Environment Canada
http://www.ec.gc.ca/
2121 Trans-Canada N. Suite 230 Téléphone/Phone: 514-421-4729
Dorval, Québec Fax: 514-421-4679
CANADA H9P 1J3 courriel/email: [email protected]
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