[ncl-talk] Computation of Density from WRF outputs
Dennis Shea
shea at ucar.edu
Sat Aug 17 10:15:58 MDT 2019
[1] NCL is language focused. Your comment/question:
",,,Qvapor, qcloud, qrain, qice, qgraupel. Do I need to account for all the
Qs? If so, how? I don’t suppose that I could just add them all up? Or is
only Qvapor relevant for kinetic energy computations in a Hurricane?"
is science focused. I'd suggest talking with your advisor.
[2] re: "How do we not have an in-built NCL function for computing NCL
already? "
I assume you mean:
"How do we not have a built-in NCL function for computing
density already?"
Please contact the WRF people: wrfhelp at ucar.edu
====================
Ideal gas law: p = (density)*RD*(temperature)
Hence:
density = p/(RD*temperature)
p => Pa
qv => kg/kg :QVAPOR
qc => kg/kg :QCLOUD
t => K
tv = t*(1+0.609*qv)
or, maybe
tv = t*(1+0.609*qv - qc)
RD = 287.04 ; [J/(K-kg)] Gas Constant dry air
density = p/(RD*tv)
On Fri, Aug 16, 2019 at 1:40 PM Prashanth Bhalachandran via ncl-talk <
ncl-talk at ucar.edu> wrote:
> Dear NCL Experts,
> I have a question regarding the computation of density from the WRF
> outputs. I specifically need to compute it for kinetic energy (rho *
> u_i^2).
>
> Since density is not an output from WRF, I currently have:
>
> Rho = ((pressure*100.)) /((287.0 *(1. + (0.608*qvapor))*temperature)).
>
> However, I realize that there are Qvapor, qcloud, qrain, qice, qgraupel.
> Do I need to account for all the Qs? If so, how? I don’t suppose that I
> could just add them all up? Or is only Qvapor relevant for kinetic energy
> computations in a Hurricane?
>
> Also, how do we not have an in-built NCL function for computing NCL
> already?
>
> Sincerely,
> Prashanth
>
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