[ferret_users] curious Ambiguous coordinates on Z axis

To: ferret_users <oar.pmel.ferret_users@xxxxxxxx>

Subject: [ferret_users] curious Ambiguous coordinates on Z axis

From: David Wang <climater@xxxxxxxxx>

Date: Thu, 02 Oct 2008 11:41:29 -0400

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Hi Ferreters,

It seems to me that if I load two netcdf files whose variables have the identical vertical axis, Ferret will still render them as different ones, and issue a warning message ("*** NOTE: Ambiguous coordinates on Z axis") when calculations are done among variables. I guess calculations are correctly done, but the message is somewhat misleading. Here is an illustrative example:

$ ln -s $FER_DSETS/data/levitus_climatology.cdf .
$ ferret
        NOAA/PMEL TMAP
        FERRET v6.1
        Linux(g77) 2.4.21-32 - 03/25/08
         2-Oct-08 11:10

yes? use "$FER_DSETS/data/levitus_climatology.cdf"
yes? use "./levitus_climatology.cdf"
yes? say `temp[d=1],return=zaxis`
!-> MESSAGE/CONTINUE ZAXLEVITR
ZAXLEVITR
yes? say `temp[d=2],return=zaxis`
!-> MESSAGE/CONTINUE ZAXLEVITR1
ZAXLEVITR1
yes? shade/y=0 temp[d=2]-temp[d=1]
*** NOTE: Ambiguous coordinates on Z axis: TEMP[D=2]-TEMP[D=1]

Thanks,
David