Re: plot mixed layer depth

[Jaison Kurian <jaison@xxxxxxxxxxxxxxxxxx>]

Hi Dominic,
              Welcome to Ferret users community. Here is an example to 
calculate mixed layer depth (mld) based on sigma_t criteria. You can also 
refer these mails in the archive :

http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_2003/msg00352.html
http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_2003/msg01168.html

Example:
-------
      set data levitus_climatology
      set reg/x=100E:280E/y=-60:60
 
! density based mld (mixed layer depth) calculation
!   temp & salt should be on same grid
!   z[gz=temp] stands for pressure in decibars(~ depth in meters)
!   density is calculated using RHO_UN function

      let density          = RHO_UN(salt,temp,z[gz=temp]) - 1000  ! kg/m3
      let sigma_t          = density - 1000 
      let mld_sig          = sigma_t[k=1] + 0.2     ! mld criteria
      let zero_at_mld_sig  = sigma_t - mld_sig
      let mld_z            = zero_at_mld_sig[z=@loc:0]

! for some sort of calculations we need to eliminate the z-grid information
!   from the mld variable. Using RESHAPE function to wrap the mld variable
!   only to X&Y-grids

      let xy_stamp         = x[gx=temp]+ y[gy=temp]
      let mld              = RESHAPE(mld_z,xy_stamp)  
      set var/title="Mixed Layer Depth (Density Criteria)"/units="meters" mld
    
      fill mld

! end of example 


Hope this helps

With Regards 

Jaison 



On Sun, 25 Jul 2004, DOMINIC RICKY FERNANDEZ wrote:

> 
> -- hi ferret users,
>                                  i m new to ferret. i would like to know how 
> to plot the mixed layer depth. where sigma(t)is 0.2 kg/m3 greater than the 
> surface.
>                      thanks in advance 
> ****************************************************
> Dominic Ricky Fernandez
> Physical Oceanography Division
> National Institute of Oceanography
> Dona Paula 403 004
> Goa, India
>  
> Tel : +91-(0)9422634637
> Tel : +91-(0)832-2450400 (O)
> Fax : +91-(0)832-2229102
> email : dominicf@darya.nio.org
>         dominic_ricky@yahoo.co.in
>         rickynio@rediffmail.com
> ******************************************************
> 

-- 
___________________________________________________

    Jaison Kurian                           
    Centre for Atmospheric and Oceanic Sciences
    Indian Institute of Science
    B A N G A L O R E   560 012
    Ph: +91-80-3942505
        +91-80-3600450
    Fax:+91-80-3600865
___________________________________________________