The Met Office Unified Model Global Atmosphere 8.0 and  JULES Global Land 9.0 configurations

Willett, Martin; Brooks, Melissa; Bushell, Andrew; Earnshaw, Paul; Smith, Samantha; Tomassini, Lorenzo; Best, Martin; Boutle, Ian; Brooke, Jennifer; Edwards, John M.; Elvidge, Andrew D.; Furtado, Kalli; Hardacre, Catherine; Hartley, Andrew J.; Hewitt, Alan J.; Johnson, Ben; Lock, Adrian; Malcolm, Andy; Mulcahy, Jane; Müller, Eike; Renfrew, Ian A.; Rumbold, Heather; Rooney, Gabriel G.; Sellar, Alistair; Ujiie, Masashi; van Niekerk, Annelize; Wiltshire, Andy; Whitall, Michael

doi:10.5194/gmd-19-1473-2026

Articles | Volume 19, issue 4

https://doi.org/10.5194/gmd-19-1473-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

GA/GL: Description of the Met Office Unified Model Global...

https://doi.org/10.5194/gmd-19-1473-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 4

Model description paper

|

20 Feb 2026

Model description paper |

| 20 Feb 2026

The Met Office Unified Model Global Atmosphere 8.0 and JULES Global Land 9.0 configurations

Martin Willett, Melissa Brooks, Andrew Bushell, Paul Earnshaw, Samantha Smith, Lorenzo Tomassini, Martin Best, Ian Boutle, Jennifer Brooke, John M. Edwards, Andrew D. Elvidge, Kalli Furtado, Catherine Hardacre, Andrew J. Hartley, Alan J. Hewitt, Ben Johnson, Adrian Lock, Andy Malcolm, Jane Mulcahy, Eike Müller, Ian A. Renfrew, Heather Rumbold, Gabriel G. Rooney, Alistair Sellar, Masashi Ujiie, Annelize van Niekerk, Andy Wiltshire, and Michael Whitall

Data sets

Supplementary material for manuscript "The Met Office Unified Model Global Atmosphere 8.0 and JULES Global Land 9.0 configurations": AMIP and DA Trial Data Martin Willett https://doi.org/10.5281/zenodo.17569816

Model code and software

Supplementary material in support of manuscript 75 “The Met Office Unified Model Global Atmosphere 8.0 and JULES Global Land 9.0 configurations”: Python scripts Martin Willett https://doi.org/10.5281/zenodo.17649117

Short summary

Global Atmosphere (GA) configurations of the Unified Model (UM) and Global Land (GL) configurations of Joint UK Land Environment Simulator (JULES) are developed for use in any global atmospheric modelling application. We describe a recent iteration of these configurations, GA8GL9, which includes improvements to the representation of convection and other physical processes. GA8GL9 is used for operational weather prediction in the UK and forms the basis for the next GA and GL configuration.