Re: [ferret_users] calculate vertical velocity in ferret

[Steve Guimond <guimond@xxxxxxxxxxxxx>]

Hi,
  Assuming the flow is Boussinesq (density constant everywhere except
where coupled with gravity i.e. incompressible) you can use

du/dx + dv/dy = -dw/dz

To do this in Ferret,

!div is dw/dz

let div = -1*(u[x=@ddc] + v[y=@ddc])

By imposing boundary conditions at the top and bottom of w=0 you can
integrate dw/dz to find the vertical velocity at each level.


Steve

=======================================================
Stephen R. Guimond
Graduate Research Assistant
Center for Ocean-Atmospheric Prediction Studies (COAPS)
=======================================================

On Mon, 26 Nov 2007, yangxing zheng wrote:

> Hi ferret_users,
>
>     I have gridded ocean data with variables including
> u,v, temp, ...
> Unfortunately I need vertical velocity w which is not
> an output of model. One way to get w is to use
> continuity equation. Does anyone have any idea how to
> do it in ferret, also how is potential error produced
> using continuity equation to calculate w?
>
>    Thanks a lot!
>
>    Yangxing
>
>
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