Re: [ferret_users] Ferret's definition of the earth radius

[Olivier Marti <olivier.marti@xxxxxxxxxxxx>]

> Le 29 févr. 2016 à 16:18, Andy Jacobson - NOAA Affiliate <andy.jacobson@xxxxxxxx> a écrit :
> 
> Hi,
> 
> I'm trying to track down a problem conserving tracer mass in the GEOS-Chem model, using an emissions module called HEMCO.  It has been suggested that differences may be due to conflicting definitions of the radius of the earth.  As it turns out, I used Ferret to do my regridding, so I'm trying to discover what value Ferret is using.  I found one definition in FERRET/fmt/cmn/gt_lib.parm (6371.e5 cm).  Is there anywhere else that a value for the radius of the earth is defined in the ferret source code?
> 
> Thanks,
> 
> Andy
> 
> -- 
> Andy Jacobson
> andy.jacobson@xxxxxxxx
> 
> NOAA Earth System Research Lab
> Global Monitoring Division
> 325 Broadway R/GMD1
> Boulder, Colorado 80305
> 
> 303/578-2237

Andy,

you can also ask to Ferret !

i.e : 

!
! What is the Earth radius in Ferret

DEFINE SYMBOL MyPrec $1"360"

DEFINE AXIS/X=0:360/NPOINTS=($MyPrec)/EDGES/UNITS=degrees_east   xax
DEFINE AXIS/Y=-90:90/NPOINTS=($MyPrec)/EDGES/UNITS=degrees_north yax

LET             aire       = 1.0 + 0*(X[GX=xax]+Y[GY=yax])
LET/UNITS="m^2" aire_sum   = `aire[X=@DIN,Y=@DIN]`
LET             pi         = `ACOS (-1.0)`
LET/UNITS="m"   ra         = `(aire_sum/ 4.0 / pi)^0.5`

LIST/NOHEAD/QUIET/FORMAT=("Earth Radius in Ferret :", 1F20.6, " m") ra

Earth Radius in Ferret :      6370499.317638 m

-- 
Dr. Olivier Marti  - mailto:olivier.marti@xxxxxxxxxxxx
Laboratoire des Sciences du Climat et de l'Environnement
Institut Pierre Simon Laplace
Laboratoire CEA-CNRS-UVSQ  -  UMR 8212
Tel : +33 1 69 08 77 27 - Mob : +33 6 45 36 43 74
Fax : +33 1 69 08 30 73
<http://www.lsce.ipsl.fr/Pisp/olivier.marti>