Tools
ToolsWillett, 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 and Whitall, Michael (2026) The Met Office Unified Model Global Atmosphere 8.0 and JULES Global Land 9.0 configurations. Geoscientific Model Development, 19 (4). pp. 1473-1517. ISSN 1991-959X
Preview |
PDF (gmd-19-1473-2026)
Available under License Creative Commons Attribution. Download (6MB) | Preview |
Abstract
We describe Global Atmosphere 8.0 and Global Land 9.0 (GA8GL9) that are science configurations of the Met Office Unified Model and Joint UK Land Environment Simulator (JULES) land surface model developed for use across weather and climate timescales. GA8GL9 builds upon GA7GL7. It not only consolidates the changes made for the climate branch configuration GA7.1GL7.1 (the atmosphere and land components of the physical model used in HadGEM3-GC3.1, UKESM1 and UKESM1.1 which were all used in the Met Office's CMIP6 submissions) and NWP branch configuration GA7.2GL8.1 (the operational global NWP model at the Met Office between 2019 and 2022), but also includes developments to most areas of the science. Some of the key changes include: prognostic-based entrainment, which adds convective memory and improves precipitation rates and spatial structures; time-smoothed convective increments, which improves the convection-dynamics coupling and greatly reduces the detrimental dynamical effects of convective intermittency; a new riming parametrisation, which increases the amount of supercooled water and hence reduces Southern Ocean biases; and a package of land surface changes, which improves the forecast of near-surface fields and hence removes the need for the aggregate surface tile in NWP applications. Several changes are made that reduce numerical artefacts and improve the numerical stability of the model. The NWP and climate performance of GA8GL9 is evaluated against the previous configuration, GA7GL7. In NWP tests GA8GL9 is shown have reduced errors and improved spatial structure. The mean climate in GA8GL9 is shown to be improved relative to GA7GL7 with notable improvements in the top of atmosphere outgoing shortwave radiation. GA8GL9 is the atmosphere and land component of GC4, and GC4 has been used as the operational global NWP model at the Met Office since May 2022.
| Item Type: | Article |
|---|---|
| Additional Information: | The authors would like to thank Anthony Jones, Dan Copsey and Warren Tennant for reviewing sections of this manuscript. The development and assessment of the Global Atmosphere/Global Land configurations are possible only through the hard work of a large number of people, both within and outside the Met Office, that exceeds the list of authors. |
| Uncontrolled Keywords: | modelling and simulation,general earth and planetary sciences,sdg 13 - climate action ,/dk/atira/pure/subjectarea/asjc/2600/2611 |
| Faculty \ School: | Faculty of Science Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA |
| UEA Research Groups: | Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 18 May 2026 13:41 |
| Last Modified: | 18 May 2026 13:41 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/103073 |
| DOI: | 10.5194/gmd-19-1473-2026 |
Downloads
Downloads per month over past year
Actions (login required)
 |
View Item |