Preprints
https://doi.org/10.5194/gmd-2022-209
https://doi.org/10.5194/gmd-2022-209
Submitted as: model description paper
30 Sep 2022
Submitted as: model description paper | 30 Sep 2022
Status: this preprint is currently under review for the journal GMD.

The second Met Office Unified Model/JULES Regional Atmosphere and Land configuration, RAL2

Mike Bush1, Ian Boutle1, John Edwards1, Anke Finnenkoetter1, Charmaine Franklin2, Kirsty Hanley1, Aravindakshan Jayakumar3, Huw Lewis1, Adrian Lock1, Marion Mittermaier1, Saji Mohandas3, Rachel North1, Aurore Porson1, Belinda Roux2, Stuart Webster1, and Mark Weeks1 Mike Bush et al.
  • 1Met Office, FitzRoy Road, Exeter, EX1 3PB, UK
  • 2Bureau of Meteorology (BoM), Melbourne, Victoria, Australia
  • 3National Centre for Medium Range Weather Forecasting (NCMRWF), Noida, India

Abstract. In this paper we define RAL2 - the second "Regional Atmosphere and Land" (RAL) science configuration for regional modelling. RAL2 uses the Unified Model (UM) as the basis for the atmosphere and the Joint UK Land Environment Simulator (JULES) for the land. RAL2 defines the science configuration of the dynamics and physics schemes of the atmosphere and land and builds on the baseline of RAL1. There are two RAL2 sub-releases, one for mid-latitudes (RAL2-M) and one for tropical regions (RAL2-T). We document the differences between them and where appropriate discuss how RAL2 relates to RAL1 and the corresponding configuration of the global forecasting model. Our results show an increase in medium and low cloud amounts in the mid-latitudes leading to improved cloud forecasts. The increase in cloud amount leads to a reduced diurnal cycle of screen temperature. There is also a reduction in the frequency of heavier precipitation rates. RAL2 is expected to be the last RAL science configuration with two sub-releases as research effort is focused on producing a single defined configuration of the model that performs effectively in all regions of the world.

Mike Bush et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2022-209', Anonymous Referee #1, 30 Oct 2022
  • RC2: 'Comment on gmd-2022-209', Anonymous Referee #2, 31 Oct 2022
  • RC3: 'Comment on gmd-2022-209', Anonymous Referee #3, 31 Oct 2022

Mike Bush et al.

Mike Bush et al.

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Short summary
Building on the baseline of RAL1, the RAL2 science configuration is used for regional modelling around the UM Partnership and in operations at the Met Office. RAL2 has been tested in different parts of the world including Australia, India and the U.K. RAL2 increases medium and low cloud amounts in the mid-latitudes compared to RAL1, leading to improved cloud forecasts and a reduced diurnal cycle of screen temperature. There is also a reduction in the frequency of heavier precipitation rates.