[ncl-talk] How to calculate d(anyvariable)/dt from a wrf file in NCL

[Dennis Shea]

I don't understand " there is no time dimension "
I-----------------

Please see *wrf_times_c*
<https://www.ncl.ucar.edu/Document/Functions/WRF_contributed/wrf_times_c.shtml>

See the examples

On Thu, Nov 24, 2022 at 9:24 PM Lyndz via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Dear NCL experts,
>
> I would like to compute the potential vorticity tendency (dPV/dt) from a
> wrf file.
> However, there is no time dimension in the variables (although the "time"
> variable can be obtained using the wrf_user_getvar)
>
> Here's my script so far:
>
> filename = "./wrfout_d01_2011-12-12_12_00_00"
> a     = addfile(filename,"r")
> times = wrf_user_getvar(a,"times",-1)                   ; get all times in
> the file
> it = 89                                                   ; first time step
> theta = wrf_user_getvar(a,"theta",it)
> pv    = wrf_user_getvar(a,"pvo",it)                     ;potential
> vorticity
>
> I would like to compute dPV/dt using centered finite difference
> (center_finite_diff_n).
>
> Any ideas/solutions/examples on how can I do this in NCL?
>
> I'll appreciate any help on this matter.
>
> -Lyndz
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