[Wrf-users] Confused about model height

[Eric Altshuler]

Hello John,

Geopotential heights are always given as height above sea level (I think the definition is more rigorous than this, but the effects of the non-spherical earth and non-uniform gravitiational fields are second-order effects). Otherwise, if height fields were computed as the height above the ground level, height fields would be distorted by the pattern of surface topography, and could not be used for calculating geostrophic winds, for example.

Best regards,

Eric L. Altshuler
Assistant Research Scientist
Center for Ocean-Land-Atmosphere Studies
4041 Powder Mill Road, Suite 302
Calverton, MD 20705-3106
USA

E-mail: ela at cola.iges.org
Phone: (301) 902-1257
Fax: (301) 595-9793

----- Original Message -----
From: "John Krasting" <krasting at envsci.rutgers.edu>
To: wrf-users at ucar.edu, "WRF Help" <wrfhelp at ucar.edu>
Sent: Tuesday, March 10, 2009 3:01:14 PM GMT -05:00 US/Canada Eastern
Subject: [Wrf-users] Confused about model height

Hi Users -

Just want to confirm exactly how height is calculated using ARWpost.

Is this the height above ground level or above sea level?  I'm
assuming that since WRF is using a terrain-following hydrostatic
coordinate, that these values are above ground level.


Thanks,
John

-----------------------------

more module_calc_height.f90
!! Diagnostics: Height

MODULE module_calc_height

  CONTAINS
  SUBROUTINE calc_height(SCR, cname, cdesc, cunits)

  USE constants_module
  USE module_model_basics

  !Arguments
  real, pointer, dimension(:,:,:)       :: SCR
  character (len=128)                   :: cname, cdesc, cunits


  SCR      = ( (PH+PHB) / G ) / 1000.
  cname    = "height"
  cdesc    = "Model height"
  cunits   = "KM"

  END SUBROUTINE calc_height

END MODULE module_calc_height
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