[ncl-talk] Supercell Composite Parameter with WRF output

[Adam Phillips]

Hi Arnaitz,
I cannot answer how to compute your BS variable, but I can answer your
second query.
Use the where function to set the conditional requirements:
BS = where(BS.gt.20,20,BS)
BS = where(BS.lt.10,0,BS)
MUCIN = where(MUCIN.gt.-40,-40,MUCIN)
https://www.ncl.ucar.edu/Document/Functions/Built-in/where.shtml
Adam


On Sun, Apr 25, 2021 at 3:26 AM Arnaitz Fernández via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Hi. I'm trying to make an NCL script for calculating in a map values of
> SCP (Supercell Composite Parameter). The definition of this parameter is:
> SCP=  (MUCAPE/1000 ) *(BS eff /20 )* (SRH eff /50 ) * (-40/MUCIN),
> where BSeff is the Bulk Shear effective and SRH effective Storm relative
> Shear.
>
> With wrf_user_getvar I can obtain values of MUCAPE, MUCIN and SRH (with
> some calculations of u and v) but I don't know how to calculate BS.
>
> Another problem is that there are some values that requires conditionals:
> if BS>20 --> BS = 20
> if BS < 10 --> BS = 0
> if MUCIN > -40 --> MUCIN  =  -40.
>
> But there are values that change between different points on the map, so I
> don't know how to do this conditionals for each point of the map. I mean, I
> can't do: if MUCIN > -40: MUCIN = -40, because this is for all points of
> the map. So, do you know how to do that???
>
> Than you.
>
>
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-- 
Adam Phillips
Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
www.cgd.ucar.edu/staff/asphilli/   303-497-1726

<http://www.cgd.ucar.edu/staff/asphilli>
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