TY - UNPB
T1 - The Met Office Unified Model Global Atmosphere 8.0 and JULES Global Land 9.0 configurations
AU - Willett, Martin
AU - Brooks, Melissa
AU - Bushell, Andrew
AU - Earnshaw, Paul
AU - Smith, Samantha
AU - Tomassini, Lorenzo
AU - Best, Martin
AU - Bouttle, Ian
AU - Brooke, Jennifer
AU - Edwards, John M.
AU - Furtado, Kalli
AU - Hardacre, Catherine
AU - Hartley, Andrew
AU - Hewitt, Alan
AU - Johnson, Ben
AU - Lock, Adrian
AU - Malcolm, Andy
AU - Mulcahy, Jane
AU - Müller, Eike
AU - Rumbold, Heather
AU - Rooney, Gabriel
AU - Sellar, Alistair
AU - Ujiie, Masashi
AU - von Niekert, Annelieze
AU - Wiltshire, Andy
AU - Whitall, Michael
PY - 2025/5/28
Y1 - 2025/5/28
N2 - We describe Global Atmosphere 8.0 and Global Land 9.0 (GA8GL9) that are science configurations of the Met Office Unified Model and 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 and NWP branch configuration GA7.2GL8.1, 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 parameterisation, 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 artifacts 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.
AB - We describe Global Atmosphere 8.0 and Global Land 9.0 (GA8GL9) that are science configurations of the Met Office Unified Model and 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 and NWP branch configuration GA7.2GL8.1, 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 parameterisation, 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 artifacts 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.
U2 - 10.5194/egusphere-2025-1829
DO - 10.5194/egusphere-2025-1829
M3 - Preprint
BT - The Met Office Unified Model Global Atmosphere 8.0 and JULES Global Land 9.0 configurations
PB - Copernicus Publications
ER -
