Re: Geostrophic currents

[William S Kessler <William.S.Kessler@xxxxxxxx>]

The following script will calculate dynamic height and geostrophic
velocities from Levitus data. This script finds DH at one level relative
to a reference level. It is a different (harder) problem to find DH and
u_g on a vertical section.

This script uses Sigma-T, but it is easy (probably better) to use
Sigma-Theta:
let zz=z[gz=temp]
let theta = theta_fo(salt,temp,zz,0)
-->> Now call rho_un with theta not temp in the script below

Billy K
----------------------------------------------------------
! find dynamic ht in ferret from Levitus
! allows specification of ref and top levels (Levitus levels only!)
! arg1=ref level
! arg2=level of DH wanted

use "[your Levitus data file]"

let/q alpha0 = 1/rho_un(35,0,0)
let/q rho = rho_un(salt,temp,0)   ! sigma-t (could use sigma-theta)
let/q sva = 1/rho - alpha0

! factors are: 100 to get dyn-cm; 1.e4 for p in Pa; 10 for geopot -> DH
let/q dh = if sva[z=$1] then (100*1.e4/10)*sva[z=$2:$1@din]

! geostrophic currents
let twomega=1.458e-4
let pi=4*atan(1)
let yy=y[g=temp]
let ff=twomega*sin(yy*pi/180)
let ugxy=(-10/ff)*dh[y=@ddc]   ! velocity in cm/s
let vgxy=(10/ff)*dh[x=@ddc]



----- Original Message -----
From: Prakya Shree Ram <srprakhya@yahoo.com>
Date: Friday, February 25, 2005 1:50 am
Subject: Geostrophic currents

> Dear Ferreters,
> 
> Is there any way one can calculate geostrophic
> currents using Levitus climatology data? Please send
> the .jnl file if any one has it.
> 
> Regards,
> Sriram
> 
> 
> =====
> -----------------------------------------------------------------
> Dr. P. Shree Ram                         
> Research Associate                                
> N.I.O, Regional Centre
> 176, Lawsons Bay Colony
> Visakhapatnam-530 017
> 
> Tel: +91-891-2539180 (Off.) +91-891-2527303 (Res) +91 9440120306 
> (Mobile)Fax   : +91-891-2543595
> 
> 
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