Re: Depth of the thermocline

[Jonathan Callahan <callahan@xxxxxxxxxxxxx>]

Fabrice,

This is relatively easy using the @DDC and @LOC transformations

http://ferret.wrc.noaa.gov/Ferret/Documentation/Users_Guide/v50_2000/Chapter3.htm#_VPID_69

Here's a short script which does what you want on the Levitus dataset. 
It is equally applicable to a 4D dataset.

Note that the grid cell positions along the Z axis determines the
possible values of  thermocline depth.  Your thermocline will be
somewhat blocky unless you apply some X and Y smoothing.

use levitus_climatology
let dtdz = temp[z=@ddc]
let dtdz_min = dtdz[z=@min]
let zero_at_min = dtdz - dtdz_min
let thermocline_rough = zero_at_min[z=@loc:0]
let thermocline = thermocline_rough[x=@sbx:11,y=@sbx:11]
set var/title="Thermocline Depth"/units="meters" thermocline
fill/lev=30 thermocline



-- Jonathan


Fabrice Vauclair wrote:
> 
> Dear Ferret users,
> I would like to calculate the thermocline depth by computing the depth of
> maximum vertical gradient in a 4D dataset. Is it possible to do that with FERRET
> ??
> Thanks a lot for your help.
> Fabrice
> 
> ----------------------------------------
> Fabrice Vauclair
> LEGOS/GRGS 14 av Ed. Belin, 31400 Toulouse Cedex 4
> FRANCE
> Tel: 05 61 33 30 04
> Fax: 05 61 25 32 05
> E-mail: Fabrice.Vauclair@cnes.fr
> -------------------------------------