UM File Manipulation Tools

There are three principle 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. ARCHER and Polaris are little-endian.

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


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 facility 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 Takes a netcdf file on a UM grid, either old dynamics or new dynamics, and creates a UM ancillary file

Additionally, the Mule UM utilities have recently been added. These replace some of the common UM utilities such as cumf and pumf.

Some tools and utilities are provided by the UK Met Office with the Ported UM installation system. These tools are available on ARCHER in the following directories:


fieldop Takes two 64 bit UM format files and creates a UM format file with the difference or the sum or the product of the data values of the files
convpp Converts 64 bit UM format file to a 64 bit PP format file
pptoanc Converts 64 bit PP format file to 64 bit ancillary files (needs a namelist file)
cumf Compares 64 bit UM format files
pumf Prints the header of 64 bit UM format files
makebc Extracts local boundary conditions from a UM dump file (needs a namelist file)
createBCThis replaces makebc at later UM versions

Documentation can be found here:

In /work/y07/y07/umshared/bin there are two other useful file utilities

change_cal : which changes the calendar type flag in the header

change_dump_date : which changes the date in the file header

change_dump_date dumpfile year month day hour minute second

all the date/time arguments are optional

Last modified 9 months ago Last modified on 10/08/16 11:41:39