Question about hail_opt in WRF hailcast.

[Kimsuhyun]

I have a few questions while doing WRF hailingcast.
First, in namelist.input, there are hailscast_opt and hails_opt.
Hailcast_opt seems like a direct option for hailcast, what exactly does the hail_opt option mean?
In the description, I think if I choose the WSM6 and WDM6 options, I turn it on, but if I set the hail_opt to =1, do I perform hailcast while considering WSM6 and WDM6?
Second, set cul_physics to 0 (off) in all domains,
Can I run the model by setting mp_physics = 6 (WSM6) and setting it to hail_opt = 1, hailcast_opt = 1?

 

[kwerner]

Hi,
To do hailcasting, you need to set hailcast_opt = 1. The other variable, hail_opt" is specific to certain microphysics schemes, to allow for ensemble perturbations of CCN and hail/graupel. Take a look at the description of the 2 variables to use for hailcasting in the Namelist chapter of the WRF Users' Guide.

 

[Kimsuhyun]

Hi,
To do hailcasting, you need to set hailcast_opt = 1. The other variable, hail_opt" is specific to certain microphysics schemes, to allow for ensemble perturbations of CCN and hail/graupel. Take a look at the description of the 2 variables to use for hailcasting in the Namelist chapter of the WRF Users' Guide.

Thank you for your response.
Additionally, I noticed that the HAILCAST_DIAM_MAX result changes when I set hailcast_opt = 1 in namelist.input and set hail_opt to 0 and 1.
Since on, off of hail_opt seems to be an option to convert graupel to HAIL in WSM, WDM6, is it better to set hailcast_opt to 1 and hail_opt to 0?
I'm asking because I don't see that in the WRF-userguide.

 

[kwerner]

Yes, if you don't want graupel parameters to be switched to hail parameters, then you should probably set hail_opt = 0. You could always run a couple quicker simulations to see which option provides the most realistic results and then use that one.