Turbulent Dissipation term in Boulac scheme

[Kazim Hussain]

I am having trouble understanding the dissipation term for turbulent kinetic energy in Boulac scheme. As per the the 1989 paper from Bougeault and Lacarrere the dissipation term is given by
dissipation term = -ceps_b * te1**1.5 / dl1 .
(assuming my understanding that te1 was the tke bounded by a lowerlimit, and dl1 the dissipation length after similar bounding)
However in the code(module_bl_boulac.F) I see instead it is :
td(iz)=-ceps_b*sqrt(te1)/dl1

This maybe because of my poor understanding of the code and the parameters but I do not find the implementation of the dissipation term anywhere else. Is it something to do with the comment in the code:
! in this routine the shear, buoyancy and part of the dissipation terms
I would please like to know the details for my own understanding. If I am mistaken, apologies! Otherwise this seems like an important term written wrongly and needs to be accounted for, maybe then the testings would also lead to different constants for the scheme and it will not be fine for me to just correct the formula?

 

[Ming Chen]

Thank you for raising this issue. Sorry that I don't have an immediate answer to your question. I will talk to our expert and get back to you.

 

[Ming Chen]

I have talked to our experts. It turns out that this term is then multiplied by tke in invert.
It is a partially implicit resolution in the sense that the full dissipation term will be:

-ceps_b*sqrt(te)/dl1 * te(n+1)

where te is tke at time n, while te(n+1) is tke at time n+1.

But this is done in the invert routine.

Hope this is helpful for you.

 

[Kazim Hussain]

This was very helpful for clarity. Thank you so much!