Re: On the the derivation with NCL

> I am trying to compute something like the following with NCL
>
> dq/dt + V.grad(q) + omega.dq/dp
>
> Where
>
> "d/dt" and "d/dp" are partial derivative
> "omega" is the vertical velocity
> "V" is the horizontal wind
> "q" is the quantity to derive
> "grad(q)" is the horizontal gradient of q
>
> There is a way to do it quickly with NCL?
> ---------------------------------

I'm not sure what you mean by "quickly".
Is there a ready made function for the equation of continuity ... no.

What type of grid is it? global [ regular or gaussian]
                         regional?

   q(time,lev,lat,lon), omega(time,lev,lat,lon)
   u(time,lev,lat,lon), v(time,lev,lat,lon)
   p(lev)
   time(time)

dqdt = center_finite_diff(q(lev|:,lat|:,lon|:,time|:),t,False,0)
dqdp = center_finite_diff(q(time|:,lat|:,lon|:,lev|:),p,False,0)

global gaussiam grid:
  q_grad_lon = q ; create arrays to hold output, same size and type as input
  q_grad_lat = q
                                ; this procedure will overwrite
                                ; values in T_grad_lon and T_grad_lat
  gradsg (q, q_grad_lon, q_grad_lat)

====
  V.grad(q) ==> u*q_grad_lon + v*q_grad_lat
  omega*dqdp ==> omega*dqdp
====

  http://www.ncl.ucar.edu/Document/Functions/Built-in/center_finite_diff.shtml

  http://www.ncl.ucar.edu/Document/Functions/Built-in/gradsg.shtml
  http://www.ncl.ucar.edu/Document/Functions/Built-in/gradsg.shtml

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Received on Sat Jul 21 2007 - 06:48:28 MDT