How to change the time coordinate..

[Raghavendra S. Mupparthy]

Hello All,

I have an ancillary file created by regridding the data to a higher resolution (n2048e) from the original source (at n1024e). I have created this using ANTS (which makes use of Iris). Now when I regrid, the time dimension is messed up.

Original n1024e cube:

>>> print(orig_cubes)

0: mass_fraction_of_ozone_in_air / (1) (time: 12; model_level_number: 70; latitude: 1536; longitude: 1)

>>> print(orig_cubes[0])

mass_fraction_of_ozone_in_air / (1) (time: 12; model_level_number: 70; latitude: 1536; longitude: 1)

     Dimension coordinates:

          time                           x                       -             -                -

          model_level_number             -                       x             -                -

          latitude                       -                       -             x                -

          longitude                      -                       -             -                x

     Auxiliary coordinates:

          level_height                   -                       x             -                -

          sigma                          -                       x             -                -

     Attributes:

          STASH: m01s00i060

          grid_staggering: 6

          source: Data from Met Office Unified Model

          um_version: 7.9

     Cell methods:

          mean: time

          mean: longitude

>>>

>>> print(orig_cubes[0].coord('time'))

DimCoord([-001-01-16 00:00:00, -001-02-15 00:00:00, -001-03-15 00:00:00,

       -001-04-14 00:00:00, -001-05-14 00:00:00, -001-06-13 00:00:00,

       -001-07-13 00:00:00, -001-08-12 00:00:00, -001-09-11 00:00:00,

       -001-10-11 00:00:00, -001-11-10 00:00:00, -001-12-10 00:00:00], standard_name='time', calendar='gregorian')

>>>

But the regridded cube's time coordinate has changed

>>> print(cubes[0])

mass_fraction_of_ozone_in_air / (1) (time: 12; model_level_number: 70; latitude: 3072; longitude: 1)

     Dimension coordinates:

          time                           x                       -             -                -

          model_level_number             -                       x             -                -

          latitude                       -                       -             x                -

          longitude                      -                       -             -                x

     Auxiliary coordinates:

          level_height                   -                       x             -                -

          sigma                          -                       x             -                -

     Attributes:

          STASH: m01s00i060

          grid_staggering: 6

          source: Data from Met Office Unified Model

          um_version: 7.9

     Cell methods:

          mean: time

          mean: longitude

>>> print(cubes[0].coord('time'))

DimCoord([-001-01-16 00:00:00, -001-02-15 00:00:00, -001-03-16 00:00:00,

       -001-04-15 00:00:00, -001-05-15 00:00:00, -001-06-14 00:00:00,

       -001-07-14 00:00:00, -001-08-13 00:00:00, -001-09-12 00:00:00,

       -001-10-12 00:00:00, -001-11-11 00:00:00, -001-12-11 00:00:00], standard_name='time', calendar='gregorian')

>>>

As can be seen from the above, the time info is all shifted after February. This in turn causes UM to generate 'RCF_ANCIL_ATMOS' error (Error message: replanca_rcf_replanca: Error in first validity time given in ancillary file).

I would like to make the regridded cube's time coordinate to match the original (n1024e) cube. How to go about it?

Regards

Raghu 

[RuthC]

Does replace_coord do what you need?  E.g.

cubes[0].replace_coord(orig_cubes[0].coord('time'))

Ruth

[Raghavendra S. Mupparthy]

Thanks Ruth! Let me try that!