wiki:ToolsAndUtilities/UmFileTools

Version 1 (modified by ros, 7 years ago) (diff)

UM File Manipulation Tools

There are three prinicple file format issues to consider

  • UM format/PP format
    The UM itself uses what is called UM format files which are direct access files. But some users and the UK Met Office convert the UM output files to PP format files which are sequential access. So many files from the UK Met Office and the BADC are PP format files not UM format files.
  • 64 bit/32 bit
    On the national HPC computers NCAS has installed the UM using 64 bit precision so output files are 64 bit but the UK Met Office utilities and many locally developed tools and utilities expect 32 bit precision files.
  • little endian/big endian
    This is just the order in which bytes are stored on the computer. HECToR and Polaris are little-endian.

The following tools are available on HECToR, the national high performance computer used by NCAS. They are stored in the directory:

/work/n02/n02/hum/bin

which should be accessible by all NCAS HPC account holders.

ff2pp Converts 64 bit UM format files but only fields files not ancillary or dump files to 32 bit PP format files
uminfo Outputs header information in a readable format for UM format file
ppinfo Outputs header information in a readable format for PP format files
umpack Removes spare headers and 'extra space' created when using well formed I/O and so reducing file sizes. This tool is called automatically when using the NCAS facilty of automatic archiving
xconv A useful tool, with a user interface, that can be used to display and plot UM file contents as well as converting file formats or for transforming data
xancil A new tool that can take a netcdf file on a UM grid, either old dynamics or new dynamics, and creates a UM ancillary file