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Latent heating limiter

This post was from a previous version of the WRF&MPAS-A Support Forum. New replies have been disabled and if you have follow up questions related to this post, then please start a new thread from the forum home page.

Dear WRF community,

In IEVA paper by Wicker & Skamarock, An Implicit-Explicit Vertical Transport Scheme for Convection Allowing Models (2020), authors stated:

For example, the High-Resolution Rapid Refresh (HRRR) model (Benjamin et al. 2016), which is based on a configuration of the Weather Research and Forecasting - Advanced Research WRF (WRF-ARW) community modeling system (Skamarock et al. 2008), uses two filters to control the magnitude of the vertical motion. The most significant filter is the reduction of latent heating by placing an upper limit on the heating rate produced by the physics parameterizations (mostly by phase changes within the cloud microphysics) at each time step

and later

The updraft data shown in Fig. 1 is adapted using data from Potvin et al. (2019). The Center for the Analysis and Prediction of Storms (CAPS, Snook et al. 2019) and the HRRR forecasts both use the latent heat limiting and w-damping...

The w-damping is obviously controlled by w_damping namelist.input flag, but would you kindly point me to the heating limiter filter configuration? It is controllable through namelist at all, or if not, how to remove it or control it's strength within code?

I would like to try some experiments without any of vertical motion limitations in order to see if that improves convection simulation in my case, and IEVA scheme might be enough to keep model from getting unstable.

Thank you in advance,
Ivan Toman
The namelist option is mp_tend_lim (&physics), which has a default value of 10 K/s
It is used in the subroutine moist_physics_finish_em (inside dyn_em/module_big_step_utilities_em.F)
Dear mr. Ming,

Thank you for your answer. I still have additional question. The User's guide states:

limit on temp tendency from microphysics latent heating when radar data assimilation is used

So, is this limiter active only when radar data assimilation is used, as guide apparently says, or it works regardless?
I know this is kind of confusing. We probably need to revise the README file.
When the option was first introduced, it had something to do with radar data DA. However, this option is extended later to be used for cases with larger time steps regardless of radar DA.
Please let me know if you have more questions.