open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi all,

In the ASCII ATMOSPHERIC DATA FILE, the latest Telemac release allows to add a selection of columns, including the units. For example:


This file gives the suggestion that the units are being read, and also in the manual
the variable CLDC is said to be possible in both octas and tenths. However, from a browse through the code it seems that the units are not used and that all formula's are assuming the data to be in octas. Am I missing some conversion step, or should we update the manual to only mention octas as allowed user input?


What I found at different places:

• telemac3d_dict (also 2d): keyword CLOUD COVER in octas or tenths
• waqtel_user (chapter 3.1): CLDC in octas or tenths
• waqtel_theory (chapter 6.3.2): cloudiness in octa or nebulosity in tenths
• exchange_with_atmosphere.f (here named NEBU): octas
• cals2d_thermic.f: octas
• meteo_telemac.f: tenths

Hello Jurjen,

Thanks for your feedback. You are partially right.

If using WAQTEL and the thermic model (coupled with TELEMAC-2D or TELEMAC-3D), you are right, cloud cover has to be given in octas as you were able to read in the dedicated subroutines/modules CALCS2D_THERMIC and EXCHANGE_WITH_ATMOSPHERE.

The line with units is read but not used, but has to exist. You can write whatever you want, but it is a good help in examples to write good units.
The "rigid" format with at least 2 lines to be read is imposed (you can also add other lines with comments starting with symbol #).

METEO_TELEMAC is a module which was initially implemented for KHIONE (ice modelling). In KHIONE, cloud cover is expected to be expressed in tenths (see THERMAL_KHIONE module and local variable CC). The management of meteo data was unified for TELEMAC-2D/3D/WAQTEL/KHIONE for release v8p2.
The unit tenths written in this module as a comment comes from the KHIONE version. Indeed, it should be written octas or tenths depending on the module (WAQTEL or KHIONE).
Perhaps the 2 thermal models from WAQTEL and KHIONE should be unified but time is missing.

For TELEMAC-2D, TELEMAC-3D dictionaries and WAQTEL manuals, the units are good but the concerned modules should be added I think. I will do it when I have time. So should it be done as well for METEO_TELEMAC module.

Hope this helps,

Chi-Tuan

Thanks for the in-depth explanation. Great if this could be added to the documentation on the mentioned places!

Thanks for the commits!

While we are at it, I have another (very minor) suggestion on the documentation.
For WAQTEL keyword COEFFICIENTS FOR CALIBRATING ATMOSPHERIC RADIATION (EMA).

The dico says that this is equal "Variable eair in the documentation"
This is incorrect e_air is always calculated by the formula given in 6.3.2 of waqtel_theory.
Instead: EMA is identical to (1 - alb_lw). This can be verified by reading that alb_lw is 0.03 and that the default of EMA is 0.97.

Suggestion to correct this in the dico-file.

Hello,

You are partially right.

For 2D, the dictionary is right.
For 3D, I agree that another explanation is needed, connected to the alb_lw variable.
Looking at what is written for atmospheric radiation in the WAQTEL theory guide and user manual, a few additional words are needed to describe the various formulae available to compute e_air in 3D.

Coming soon...

Chi-Tuan