[MITgcm-support] geostrophic velocity in the model

[Ichiro Fukumori]

At 10:49 AM 4/15/2004 -0700, Dimitris Menemenlis wrote:
>Does anyone know what is best way to diagnose the geostrophic component
>of velocity from the model.
>
>Specifically, should we assume that sea-surface height contains
>the least amount of ageostrophic contributions and reference
>everything to ETA.

This is not an assumption, and this should be the way to do it.  You
need pressure gradient to calculate geostrophic velocity.  Pressure is
computed hydrostatically from the surface plus sea level; sea level
gradient gives surface pressure gradient.  Even if ageostrophic flow
changes sea level, pressure gradient, and consequently geostrophic
velocity, is thus strictly dependent on ETA.

-- Ichiro


>Or is it preferable to pick mid-depth U/V as a reference.
>
>Or is there a better way?
>
>We are looking at North Pacific (~200E, 30N) and 10daily to monthly
>data.
>
>Dimitris
>Sab
>--
>Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
>Jet Propulsion Lab, California Insitute of Technology
>MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
>tel: 818-354-1656;  fax: 818-393-6720
>
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>MITgcm-support at mitgcm.org
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===============================================================
Ichiro Fukumori               | Jet Propulsion Laboratory
e-mail: fukumori at jpl.nasa.gov | Mail Stop 300-323
phone: +1 (818) 354-6965      | 4800 Oak Grove Drive
fax: +1 (818) 393-6720        | Pasadena, California 91109, U.S.A.
===============================================================