The Met Office Unified Model Global Atmosphere 4.0 and JULES Global Land 4.0 configurations

Abstract

Abstract. We describe Global Atmosphere 4.0 (GA4.0) and Global Land 4.0 (GL4.0): configurations of the Met Office Unified Model and JULES (Joint UK Land Environment Simulator) community land surface model developed for use in global and regional climate research and weather prediction activities. GA4.0 and GL4.0 are based on the previous GA3.0 and GL3.0 configurations, with the inclusion of developments made by the Met Office and its collaborators during its annual development cycle. This paper provides a comprehensive technical and scientific description of GA4.0 and GL4.0 as well as details of how these differ from their predecessors. We also present the results of some initial evaluations of their performance. Overall, performance is comparable with that of GA3.0/GL3.0; the updated configurations include improvements to the science of several parametrisation schemes, however, and will form a baseline for further ongoing development.

The Met Office HadGEM3-ES chemistry–climate model: evaluation of stratospheric dynamics and its impact on ozone

“…For example, the horizontal and vertical resolutions have increased from 3.75 • longitude × 2.5 • latitude and 60 vertical levels (model lid at 84 km). There have also been improvements to the atmosphere model physics and the addition of new ocean and sea ice components, all of which are documented in detail in Hewitt et al (2011), Walters et al (2011), and Walters et al (2014. A significant result of these model improvements is the much reduced temperature bias at the tropical tropopause layer, which in CCMVal-2 required the models based on MetUM to prescribe water vapour in this region.…”

“…It has a horizontal resolution of 1.875 • longitude × 1.25 • latitude and 85 levels in the vertical, covering an altitude range of 0-85 km. This is coupled to the Global Land 4.0 (GL4.0) configuration of the JULES land surface model (Walters et al, 2014). For simulations requiring ocean and sea ice components, the Nucleus for European Modelling of the Ocean (NEMO v3.4;Madec, 2008) model, with a 1 • resolution (ORCA-1) and 70 vertical levels, is used along with the Los Alamos sea ice model (CICE v4.1;Hunke and Lipscomb, 2008).…”

“…The underlying atmosphere model is the Global Atmosphere 4.0 (GA4.0) configuration of HadGEM3 (Walters et al, 2014) and is based on the Met Office's Unified Model (MetUM). It has a horizontal resolution of 1.875 • longitude × 1.25 • latitude and 85 levels in the vertical, covering an altitude range of 0-85 km.…”

PALADYN v1.0, a comprehensive land surface–vegetation–carbon cycle model of intermediate complexity

“…It is taken to be equal to 0.96 for all vegetation types, 0.9 for bare soil, 0.99 for snow-covered ground and 0.99 for ice (Jin and Liang, 2006;Walters et al, 2014).…”

Using satellite observations of precipitation and soil moisture to constrain the water budget of a land surface model

“…We used the global land configuration 4.0 of JULES designed for use across weather and 10 climate modelling timescales and systems (Walters et al, 2014). JULES is typically run with 4 soil layers, with the top layer being 10 cm deep.…”