Re: [ferret_users] Opening identical datasets define axis that are shared

["Ansley C. Manke" <ansley.b.manke@xxxxxxxx>]

By the way, the qualifier /LIKE= lets you get the attributes from an existing axis when defining an axis.

DEFINE AXIS/LIKE=axis_name  my_axis = ...

so you could do that instead of getting the time origin and units from the axis in your DEFINE command.

-Ansley

On 3/21/2019 8:03 AM, Patrick Brockmann wrote:

Hi ferreters,

I have encountered a problem when I open multiple identical datasets.

I can see that time axis are not defined for each dataset but shared.

It is a strategy.

But as a consequence, if I apply a change on a axis (for example a 10 days offset on the 1st one) then

other variables that share the time axis get this offset as well.

Is there a way to force ferret to define a unique time axis for each dataset ?

Below a simplified script that shows the problem.

!==============================================================================

cancel data/all; cancel var/all; cancel axis/all
 
use http://vesg.ipsl.upmc.fr/thredds/dodsC/work_thredds/p86pasb/IPSLCM6/PROD/midHolocene/CM61-LR-H6k-03/MONITORING/files/ATM_t2m_global_prio_ave.nc
use http://vesg.ipsl.upmc.fr/thredds/dodsC/work_thredds/p86pasb/IPSLCM6/PROD/midHolocene/CM61-LR-H6k-02/MONITORING/files/ATM_t2m_global_prio_ave.nc

let var=T2M_GLOBAL_PRIO[L=@SBX:120]

show axis `var[d=1], return=taxis`
show axis `var[d=2], return=taxis`

let tt = t[gt=`var[d=2],return=taxis`]
define axis/t/t0="`var[d=2],return=t0`"/units="`var[d=2],return=tunits`"/calendar="`var[d=2],return=cal`" `var[d=2],return=taxis` = tt + `10*24*60*60`

show axis `var[d=1], return=taxis`
show axis `var[d=2], return=taxis`

!==============================================================================

I get a note from ferret telling

Replacing definition of axis TIME_COUNTER
           *** NOTE: grid GOO1 used by data set ATM_t2m_global_prio_ave
           *** NOTE: Redefinition may alter apparent contents of data set
           *** NOTE: grid GOO2 used by data set ATM_t2m_global_prio_ave
           *** NOTE: Redefinition may alter apparent contents of data set

How could I do then to apply an offset on the 2nd dataset without modifying the 1st one ?

Thanks

Patrick

--
Data Analysis and Visualization Engineer / Project Manager
LSCE/IPSL, CEA-CNRS-UVSQ laboratory
LSCE - Climate and Environment Sciences Laboratory
IPSL - Institut Pierre Simon Laplace
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