Atmosphere WG Meeting minutes 21 Oct 2026
21 participants online
Chair: Sonya Fiddes
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Community updates
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From Cylc 7 to Cylc 8: Migrating UM Suites. Martin Dix, ACCESS-NRI
- Key reason why the transition is happening is because Cylc 7 is based on python 2
- Key changes are in the interface (GUI/TUI), directory structure and commands/syntax (e.g. suites are now called workflows)
- There is a nice TUI for interacting with Cylc 8, otherwise you can use the GUI via ARE
- rose edit should work with UM vn13.7 and above. For versions prior, there are some issues with stash (but this can be fixed).
- See Cylc 8 migration guide for more details
- Most models (including rAM3 and AM3) will work in Cylc 8 with the Cylc 7 compatibility mode. Otherwise, some minor changes are required to rc files to fully update the suite to Cylc 8.
- If people are having issues with the transition, they can post on the Hive forum for help.
- Sonya/Martin: There are issues with swapping between Cylc 7 and Cylc 8, so it is not advised to do this. For example, it is difficult to clean suites properly.
- Sonya: Are there plans to make the Cylc 8 GUI available outside ARE? Martin/Lachlan: It can work via SSH tunnelling. There is also potential to set up Cylc hub on NCI that can be used from the command line if there is enough demand (this is currently technically difficult to set up).
- Bethan: Can log files be seen through the TUI? Martin/Sonya: Yes but a little tricky to find initially
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The ‘Black Summer’ Currowan fire: insights from a case study. Mika Peace, BoM
- The project analyses fire meteorology case studies to help with decision making in future events
- For this case, the wind change and fire weather conditions on the ground were not really represented by station observations
- Regional atmospheric ACCESS is used to simulate the event coupled with a fire spread model (ACCESS-Fire)
- Recent updates to ACCESS-Fire includes a change to the AFDRS fuel model (previously FFDI)
- Simulations are on a 100 m horizontal grid, with 140 vertical levels and 1 minute output
- A detailed analysis of the southerly wind change and fire spread in the model is presented (more details in Kevin’s work).
- A very cool 3d visualisation has been produced with ACCESS-NRI/NCI (not yet publically available?)
- The suite can be run with or without the fire model and used for other cases at 100 m or 300 m grid spacing, and Mika encourages others to consider using this for their work.
- Bethan: Is there a sub-grid turbulence scheme switched on at this scale? Mika: Yes, but talk to Harvey for more details
- Martin: What causes the strong winds shown at the leading edge of the fire? Mika: Combination of local factors generated by the fire, but we are looking into this more.
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Other items from Heidi and Sonya:
- ACCESS-NRI EOIs are open for another few days for ACCESS-ESM3 development and evaluation
- BoM is seeking input for BARRA3, see survey here
- Online registration is still open for the 7th Momentum Partnership Convective-Scale Modelling Workshop (Singapore)
- Abstracts submission deadline has been extended for the Convection-Permitting Modelling Workshop 2027 (UNSW, Sydney)