How to set-up the MYNN-EDMF scheme

[afernandezody]

Hello,
After listening to Monday's talk and scanning the NOAA technical memorandum, I'm still not 100% sure on how to set up MYNN-EDMF v3.0 versus v2.7 (especially on whether to deactivate the mass-flux scheme). Using most default flags, I came up with: an initial snippet:
bl_pbl_physics = 5
bl_mynn_closure = 2.7
bl_mynn_mixlength = 2
bl_mynn_cloudpdf = 2
bl_mynn_edmf = 1
bl_mynn_edmf_mom = 0
bl_mynn_edmf_tke = 0
bl_mynn_cloudmix = 1
bl_mynn_mixqt = 0
bl_mynn_ess = 1
bl_mynn_tkeadvect = F
bl_mynn_mixaerosols = 1
bl_mynn_mixnumcon = 1
bl_mynn_mixscalars = 0
icloud_bl = 1
I have 2 related questions:
Q1 - Would this be a recommended starting point to use MYNN-EDMF v2.7?
Q2 - If upgrading to bl_mynn_closure = 3.0, would I need to modify any of the parameters? My main concern is whether bl_mynn_edmf should be switch to a value of 0.
Thanks.

 

[kwerner]

Hi,
I want to let you know we are contacting our MYNN collaborators for suggestions. We will get back to you as soon as we have a response. Thank you for your patience.

 

[joeolson42]

First, I wouldn't consider 2.7 or 3.0 to be an upgrade compared to 2.6. The differences will be small and may not be better. The most well-tested configuration is:

bl_pbl_physics = 5
bl_mynn_closure = 2.6
bl_mynn_mixlength = 1
bl_mynn_cloudpdf = 2
bl_mynn_edmf = 1
bl_mynn_edmf_mom = 1
bl_mynn_edmf_tke = 0
bl_mynn_cloudmix = 1
bl_mynn_mixqt = 0
bl_mynn_ess = 0
bl_mynn_tkeadvect = F
bl_mynn_mixaerosols = 1
bl_mynn_mixnumcon = 1
bl_mynn_mixscalars = 0
icloud_bl = 1

I'd recommend using the same configuration options with bl_mynn_closure = 2.7 and 3.0.
If you use level 3.0 and keep bl_mynn_edmf = 1 (recommended), it will negate the countergradient terms and rely on the mass-flux component for nonlocal mixing.
If you use level 3.0 and set bl_mynn_edmf = 0 (original scheme), it will shut off the mass-flux component and use the countergradient terms to represent nonlocal mixing. The shallow cumulus clouds will be degraded, so this configuration is not recommended. I really only maintain this option for historical reasons.

-joe