STF JULES Code Migration

2026-11-03

The Met Office is developing a surface transport forecasting capability based on JULES (Joint UK Land Environment Simulator) to support operational road and rail forecasting applications.  JULES was originally developed as a land-surface model for representing natural surfaces such as vegetation and soil. In its native form, it does not adequately represent key physical processes associated with road and rail surfaces, including impermeable surface behaviour, rapid water drainage and realistic snowmelt.  To address this, the Met Office has already developed and scientifically evaluated an STF-JULES ("Surface Transport Forecasting JULES") capability based off a forked older version (v5.9) of the JULES codebase This includes:  configuration and parameter tuning for road and rail surfaces;  modifications to surface hydrology behaviour to represent impermeable transport surfaces;  modifications to thermal conductivity and heat capacity handling; implementation of a road drainage/run-off scheme;  modifications to snow handling to retain meltwater within the road surface water store .  The existing source code modifications are contained within a small number of JULES routines:  heat_con_jls_mod.F90  soil_htc_jls_mod.F90  road_drain_jls_mod.F90  surf_hyd_jls_mod.F90  The supplier is required to migrate the existing STF-JULES developments into the latest JULES version and complete the work through to successful merge into the main JULES master branch.  In addition to porting these routines, the supplier shall:  identify and migrate all associated namelist, Rose suite and configuration file changes;  identify differences in output behaviour with the existing STF-JULES implementation;  deliver the changes through to successful integration into the JULES master branch.   The work shall be considered complete when:  all agreed STF-JULES science developments have been successfully migrated into the latest supported JULES version;  all required namelists, Rose suites and configuration files have been updated;  regression testing demonstrates no major unexplained changes relative to the existing STF-JULES implementation;  a technical comparison report has been delivered describing:  differences between the original STF-JULES v5.9 implementation and the migrated implementation;  any changes in behaviour or performance;  any known limitations or unresolved issues;  all required technical documentation has been updated; and  the changes have been successfully merged into the main JULES master branch.  The supplier shall provide the following deliverables:  1. A one-page delivery and migration plan within one week of contract award.   2. Updated STF-JULES implementation within the latest supported JULES version by [DATE PROPOSED BY SUPPLIER], including:  migrated source code changes;  updated namelists, and configuration files   3. A technical comparison and validation report by [DATE PROPOSED BY SUPPLIER], containing:      comparison between the original STF-JULES v5.9 implementation and the migrated implementation;  investigation into, and description of, any differences in behaviour or performance;  explanation of expected differences arising from JULES version changes;  summary of any known limitations or unresolved issues.  4. Completion of all activities required to integrate the migrated STF-JULES capability into the main JULES master branch including:  arranging and coordinating formal code review through the JULES development process;  implementing required revisions;  updating technical and code documentation as required by the JULES review process; and  successful merge into the JULES master branch.

United Kingdom (UK)

2026-09-02