Problems with Met Office backgrounds

[Ian Culverwell]

ROM SAF Helpdesk Eqn 341 has highlighted an embarrassment: there is no documented way of generating background data (i.e. level 2b/2d) in ROPP format. The enquirer wanted to convert Unified Model (UM) 'fieldsfiles' into ROPP format. There is no more-or-less automated way to do this, unlike for ECMWF data, which can be converted into ROPP format using either grib2bgrasc or bgrasc2ropp.

We should probably look at introducing a tool to do this conversion. This is not just code work, however: there are real questions about precisely which UM fields should populate the ROPP file. geop_sfc and press_sfc appear to be particularly problematic. See Enq 341 (​http://www.romsaf.org/view_admin_enquiry.php?id=341) for more.

While we're at it, Sec 3.67 of the ROPP FM UG needs attention: Fig 3.4 has mislabelled levels (I think it should be rho/A and theta/B), and there is no mention of the fact that ZA is calculated from ZB (by linear interpolation), not given.

[Ian Culverwell]

The points in the last paragraph have been fixed at r5467.

[Ian Culverwell]

Chris Burrows pointed me to some useful source code in https://trac.romsaf.org/ropp/browser/ropp_test/trunk/programs/meto_test.

ropp_read_nc_data reads from example files like /data/local/cburrows/opsout/20110730*.nc*, which don't exist any more, but Chris tells me that Neill keep a rolling archive of source data in: /scratch/frnb/gpsro_mon/mon_files_ba and /scratch/frnb/gpsro_mon/mon_files_ref

They are produced by an offline run of the OPS (which does the spatial and temporal interpolations from the model grid points to the observation locations) and they are then used to produce all the plots on the monitoring pages.