[MITgcm-support] definition of gravFacC and gravFacF

[Jean-Michel Campin]

Hi Angela,

Two things:
1) gravity that varies with height can be specified: 
      gravityFile='gravity_vector_Nr_long'
   in 1rst namelist "PARM01"
   units: m/s^2 ; location is at level center (rC).
   And the model constant "gravity" is used as the surface
   value, i.e., gravity at rF(1)
2) it's not implemented for pressure coordinate (a stop in 
 config_check.F), and this answer is still relevant:
   http://mitgcm.org/pipermail/mitgcm-support/2011-January/006960.html
 It's not working neither with z* coordinate (an other stop in
  config_check.F) but I don't remember why.

Cheers,
Jean-Michel

On Thu, Apr 27, 2017 at 09:10:19AM -0600, Angela Zalucha wrote:
> Dear Jean-Michel,
> 
> So then is gravFacC something that can be set or is it something
> that is calculated?  My ultimate question is has the MITgcm been
> updated such that gravity varies with height instead of assuming the
> gravitational forcing is the same as that at the surface?  For
> example, for Pluto the solid body radius is 1900 km, but the
> atmosphere that we model extends to 600 km, so the assumption of a
> constant gravitational force with height is very bad at high
> altitudes.
> 
> Angela
> 
> 
> 
> On 04/27/2017 06:45 AM, Jean-Michel Campin wrote:
> >Hi Angela,
> >
> >Here is what I found in PARAMS.h, lines 582,583:
> >C     gravFacC   :: gravity factor (vs surf. gravity) vert. profile at cell-Center
> >C     gravFacF   :: gravity factor (vs surf. gravity) vert. profile at cell-interF
> >meaning that:
> >  gravity at z=rC(k) is = gravFacC(k)*gravity
> >  gravity at z=rF(k) is = gravFacF(k)*gravity
> >and gravFacF(1) is assumed to be equal to one.
> >
> >Does this answer your question ?
> >
> >Cheers,
> >Jean-Michel
> >
> >On Thu, Apr 27, 2017 at 01:04:32AM -0600, Angela Zalucha wrote:
> >>Hi,
> >>
> >>What are the definitions (in words) of gravFacC and gravFacF?  It is
> >>not given in PARAMS.h .
> >>
> >>Thanks,
> >>
> >>Angela
> >>
> >>
> >>-- 
> >>=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=
> >>Angela Zalucha, Ph.D.
> >>Research Scientist
> >>SETI Institute
> >>+1 (617) 894-2937
> >>http://www.seti.org/users/azalucha
> >>https://www.linkedin.com/in/angela-zalucha-57451749
> >>=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=
> >>
> >>
> >>_______________________________________________
> >>MITgcm-support mailing list
> >>MITgcm-support at mitgcm.org
> >>http://mitgcm.org/mailman/listinfo/mitgcm-support
> >_______________________________________________
> >MITgcm-support mailing list
> >MITgcm-support at mitgcm.org
> >http://mitgcm.org/mailman/listinfo/mitgcm-support
> 
> -- 
> =^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=
> Angela Zalucha, Ph.D.
> Research Scientist
> SETI Institute
> +1 (617) 894-2937
> http://www.seti.org/users/azalucha
> https://www.linkedin.com/in/angela-zalucha-57451749
> =^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=|=^^=
> 
> 
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support