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1. GOSI9: UK Global Ocean and Sea Ice configurations.

Author

Guiavarc'h, Catherine, Storkey, David, Blaker, Adam T., Blockley, Ed, Megann, Alex, Hewitt, Helene, Bell, Michael J., Calvert, Daley, Copsey, Dan, Sinha, Bablu, Moreton, Sophia, Mathiot, Pierre, and An, Bo

Subjects
ANTARCTIC Circumpolar Current, NUMERICAL weather forecasting, OCEANOGRAPHY, SPATIAL resolution, ALBEDO
Abstract

The UK Global Ocean and Sea Ice configuration version 9 (GOSI9) is a new traceable hierarchy of three model configurations at 1, 1/4 and 1/12° based on version 4.0.4 of the NEMO code. GOSI9 has been developed as part of the UK's Joint Marine Modelling Programme (JMMP), a partnership between the Met Office, the National Oceanography Centre, the British Antarctic Survey, and the Centre for Polar Observation and Modelling. Following a seamless approach, it will be used for a variety of applications across a wide range of spatial and temporal resolutions: short-range coupled numerical weather prediction (NWP) forecasts, ocean forecasts, seasonal and decadal forecasts, and climate and Earth system modelling. The GOSI9 configurations are described in detail with a special focus on the updates since the previous version (GO6-GSI8). Results from 30-year ocean–ice integrations forced by CORE2 fluxes are presented for the three resolutions, and the impacts of the updates are assessed using the 1/4° integrations. The upgrade to NEMO 4.0.4 includes a new sea ice model SI3 (Sea Ice modelling Integrated Initiative) and faster integration achieved through the use of partially implicit schemes that allow a significant increase in the length of the time step. The quality of the simulations is generally improved compared to GO6-GSI8. The temperature and salinity drifts are largely reduced thanks to the upgrade to NEMO 4.0.4 and the adoption of fourth-order horizontal and vertical advections helping to reduce the numerical mixing. To improve the representation of the Southern Ocean, a scale-aware form of the Gent–McWilliams parameterization and the application of a partial-slip lateral boundary condition on momentum in the Southern Ocean have been added, resulting in a stronger and more realistic Antarctic Circumpolar Current (ACC) transport and a reduction in the temperature and salinity biases along the shelf of Antarctica. In the Arctic, the representation of sea ice is improved, leading to a reduction in surface temperature and salinity biases. In particular, the excessive and unrealistic Arctic summer sea ice melt in GO6-GSI8 is significantly improved in GOSI9 and can be attributed to the change in the sea ice model and to the higher albedos that increased sea ice thickness. [ABSTRACT FROM AUTHOR]

Published
2025
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3. Supplementary material to "GOSI9: UK Global Ocean and Sea Ice configurations"

Author

Guiavarc'h, Catherine, primary, Storkey, Dave, additional, Blaker, Adam T., additional, Blockley, Ed, additional, Megann, Alex, additional, Hewitt, Helene T., additional, Bell, Michael J., additional, Calvert, Daley, additional, Copsey, Dan, additional, Sinha, Bablu, additional, Moreton, Sophia, additional, Mathiot, Pierre, additional, and An, Bo, additional

Published
2024
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4. GOSI9: UK Global Ocean and Sea Ice configurations

Author

Guiavarc'h, Catherine, primary, Storkey, Dave, additional, Blaker, Adam T., additional, Blockley, Ed, additional, Megann, Alex, additional, Hewitt, Helene T., additional, Bell, Michael J., additional, Calvert, Daley, additional, Copsey, Dan, additional, Sinha, Bablu, additional, Moreton, Sophia, additional, Mathiot, Pierre, additional, and An, Bo, additional

Published
2024
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5. The sea ice component of GC5: coupling SI3 to HadGEM3 using conductive fluxes.

Author

Blockley, Ed, Fiedler, Emma, Ridley, Jeff, Roberts, Luke, West, Alex, Copsey, Dan, Feltham, Daniel, Graham, Tim, Livings, David, Rousset, Clement, Schroeder, David, and Vancoppenolle, Martin

Subjects
ATMOSPHERIC models, OCEAN, EARTH (Planet), SEA ice
Abstract

We present an overview of the UK's Global Sea Ice model configuration version 9 (GSI9), the sea ice component of the latest Met Office Global Coupled model, GC5. The GC5 configuration will, amongst other uses, form the physical basis for the HadGEM3 (Hadley Centre Global Environment Model version 3) climate model and UKESM2 (UK Earth System Model version 2) Earth system model that will provide the Met Office Hadley Centre/UK model contributions to CMIP7 (Coupled Model Intercomparison Project Phase 7). Although UK ocean model configurations have been developed for many years around the NEMO (Nucleus for European Modelling of the Ocean) ocean modelling framework, the GSI9 configuration is the first UK sea ice model configuration to use the new native NEMO sea ice model, SI3 (Sea Ice modelling Integrated Initiative). This replaces the CICE (Community Ice CodE) model used in previous configuration versions. In this paper we document the physical and technical options used within the GSI9 sea ice configuration. We provide details of the implementation of SI3 into the Met Office coupled model and the adaptations required to work with our "conductivity coupling" approach and provide a thorough description of the GC5 coupling methodology. A brief evaluation of sea ice simulated by the GC5 model is included, with results compared to observational references and a previous Global Coupled model version (GC3.1) used for CMIP6, to demonstrate the scientific credibility of the results. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Publisher Correction: Critical Southern Ocean climate model biases traced to atmospheric model cloud errors

Author

Hyder, Patrick, Edwards, John M., Allan, Richard P., Hewitt, Helene T., Bracegirdle, Thomas J., Gregory, Jonathan M., Wood, Richard A., Meijers, Andrew J. S., Mulcahy, Jane, Field, Paul, Furtado, Kalli, Bodas-Salcedo, Alejandro, Williams, Keith D., Copsey, Dan, Josey, Simon A., Liu, Chunlei, Roberts, Chris D., Sanchez, Claudio, Ridley, Jeff, Thorpe, Livia, Hardiman, Steven C., Mayer, Michael, Berry, David I., and Belcher, Stephen E.

Published
2018
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11. Critical Southern Ocean climate model biases traced to atmospheric model cloud errors

Author

Hyder, Patrick, Edwards, John M., Allan, Richard P., Hewitt, Helene T., Bracegirdle, Thomas J., Gregory, Jonathan M., Wood, Richard A., Meijers, Andrew J. S., Mulcahy, Jane, Field, Paul, Furtado, Kalli, Bodas-Salcedo, Alejandro, Williams, Keith D., Copsey, Dan, Josey, Simon A., Liu, Chunlei, Roberts, Chris D., Sanchez, Claudio, Ridley, Jeff, Thorpe, Livia, Hardiman, Steven C., Mayer, Michael, Berry, David I., and Belcher, Stephen E.

Published
2018
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13. The sea ice component of GC5: coupling SI3 to HadGEM3 using conductive fluxes.

Author

Blockley, Ed, Fiedler, Emma, Ridley, Jeff, Roberts, Luke, West, Alex, Copsey, Dan, Feltham, Daniel, Graham, Tim, Livings, David, Rousset, Clement, Schroeder, David, and Vancoppenolle, Martin

Subjects
OFFICES, SEA ice, COMMUNITIES, ATMOSPHERIC models, OCEAN
Abstract

We present an overview of the UK's Global Sea Ice model configuration version 9 (GSI9), the sea ice component of the latest Met Office Global Coupled model, GC5. The GC5 configuration will, amongst other uses, form the physical basis for the HadGEM3 (Hadley Centre Global Environment Model version 3) climate model and UKESM2 (UK Earth System Model version 2) Earth system model that will provide the Met Office Hadley Centre/UK model contributions to CMIP7 (Coupled Model Intercomparison Project Phase 7). Although ocean model configurations have been developed for many years around the NEMO (Nucleus for European Modelling of the Ocean) ocean modelling framework, the GSI9 configuration is the first UK sea ice model configuration to use the new native NEMO sea ice model, SI3 (Sea Ice modelling Integrated Initiative). This replaces the CICE (Community Ice CodE) model used in previous configuration versions. In this paper we document the physical and technical options used within the GSI9 sea ice configuration. We provide details of the implementation of SI3 into the Met Office coupled model and the adaptations required to work with our 'conductivity coupling' approach, and also provide a thorough description of the GC5 coupling methodology. A brief evaluation of sea ice simulated by the GC5 model is included, with results compared to observational references and a previous Global Coupled model version (GC3.1) used for CMIP6, to demonstrate the scientific credibility of the results. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Heat balance in the Nordic Seas in a global 1/12° coupled model

Author

Treguier, Anne-marie, Mathiot, Pierre, Graham, Tim, Copsey, Dan, Lique, Camille, Sterlin, Jean, Treguier, Anne-marie, Mathiot, Pierre, Graham, Tim, Copsey, Dan, Lique, Camille, and Sterlin, Jean

Abstract

The Nordic Seas are a gateway to the Arctic Ocean, where Atlantic water undergoes a strong cooling during its transit. Here we investigate the heat balance of these regions in the high resolution Met Office Global Coupled Model GC3 with a 1/12_ grid. The GC3 model reproduces resolution Met Office Global Coupled Model GC3 with a 1/12_ grid. The GC3 model reproduces the contrasted ice conditions and ocean heat loss between the eastern and western regions of the Nordic Seas. In the west (Greenland and Iceland seas), the heat loss experienced by the ocean is stronger than the atmospheric heat gain, because of the cooling by ice melt. The latter is a major contribution to the heat loss over the path of the East Greenland Current and west of Svalbard. In the model, surface fluxes balance the convergence of heat in each of the eastern and western regions. The net east-west heat exchange, integrated from Fram Strait to Iceland, is relatively small: the westward heat transport of the Return Atlantic Current over Knipovich Ridge balances the eastward heat transport by the East Icelandic Current. Time fluctuations, including eddies, are a significant contribution to the net heat transports. The eddy flux represents about 20% of the total heat transport in Denmark Strait and across Knipovich Ridge. The coupled ocean-atmosphere-ice model may overestimate the heat imported from the Atlantic and exported to the Arctic by 10 or 15%. This confirms the tendency toward higher northward heat transports as model resolution is refined, which will impact scenarios of future climate.

Published
2021
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18. Dynamical downscaling of unforced interannual sea-level variability in the North-West European shelf seas

Author

Tinker, Jonathan (author), Palmer, Matthew D. (author), Copsey, Dan (author), Howard, Tom (author), Lowe, Jason A. (author), Hermans, T.H.J. (author), Tinker, Jonathan (author), Palmer, Matthew D. (author), Copsey, Dan (author), Howard, Tom (author), Lowe, Jason A. (author), and Hermans, T.H.J. (author)

Abstract

Variability of Sea-Surface Height (SSH) from ocean dynamic processes is an important component of sea-level change. In this study we dynamically downscale a present-day control simulation of a climate model to replicate sea-level variability in the Northwest European shelf seas. The simulation can reproduce many characteristics of sea-level variability exhibited in tide gauge and satellite altimeter observations. We examine the roles of lateral ocean boundary conditions and surface atmospheric forcings in determining the sea-level variability in the model interior using sensitivity experiments. Variability in the oceanic boundary conditions leads to uniform sea-level variations across the shelf. Atmospheric variability leads to spatial SSH variability with a greater mean amplitude. We separate the SSH variability into a uniform loading term (change in shelf volume with no change in distribution), and a spatial redistribution term (with no volume change). The shelf loading variance accounted for 80% of the shelf mean total variance, but this drops to ~ 60% around Scotland and in the southeast North Sea. We analyse our modelled variability to provide a useful context to coastal planners and managers. Our 200-year simulation allows the distribution of the unforced trends (over 4–21 year) of sea-level changes to be quantified. We found that the 95th percentile change over a 4-year period can lead to coastal sea-level changes of ~ 58 mm, which must be considered when using smooth sea level projections. We also found that simulated coastal SSH variations have long correlation length-scales, suggesting that observations of interannual sea-level variability from tide gauges are typically representative of > 200 km of the adjacent coast. This helps guide the use of tide gauge variability estimates., Physical and Space Geodesy

Published
2020
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19. The low-resolution version of HadGEM3 GC3.1: development and evaluation for global climate

Author

Kuhlbrodt, Till, Jones, Colin G., Sellar, Alistair, Storkey, Dave, Blockley, Ed, Stringer, Marc, Hill, Richard, Graham, Tim, Ridley, Jeff, Blaker, Adam, Calvert, Daley, Copsey, Dan, Ellis, Richard, Hewitt, Helene, Hyder, Patrick, Ineson, Sarah, Mulcahy, Jane, Siahaan, Antony, and Walton, Jeremy

Subjects
Meteorology and Climatology
Abstract

A new climate model, HadGEM3 N96ORCA1, is presented that is part of the GC3.1 configuration of HadGEM3. N96ORCA1 has a horizontal resolution of ~135 km in the atmosphere and 1° in the ocean and requires an order of magnitude less computing power than its medium‐resolution counterpart, N216ORCA025, while retaining a high degree of performance traceability. Scientific performance is compared to both observations and the N216ORCA025 model. N96ORCA1 reproduces observed climate mean and variability almost as well as N216ORCA025. Patterns of biases are similar across the two models. In the northwest Atlantic, N96ORCA1 shows a cold surface bias of up to 6 K, typical of ocean models of this resolution. The strength of the Atlantic meridional overturning circulation (16 to 17 Sv) matches observations. In the Southern Ocean, a warm surface bias (up to 2 K) is smaller than in N216ORCA025 and linked to improved ocean circulation. Model El Niño/Southern Oscillation and Atlantic Multidecadal Variability are close to observations. Both the cold bias in the Northern Hemisphere (N96ORCA1) and the warm bias in the Southern Hemisphere (N216ORCA025) develop in the first few decades of the simulations. As in many comparable climate models, simulated interhemispheric gradients of top‐of‐atmosphere radiation are larger than observations suggest, with contributions from both hemispheres. HadGEM3 GC3.1 N96ORCA1 constitutes the physical core of the UK Earth System Model (UKESM1) and will be used extensively in the Coupled Model Intercomparison Project 6 (CMIP6), both as part of the UK Earth System Model and as a stand‐alone coupled climate model.

Published
2018
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20. Corrigendum

Author

Smith, Doug M., primary, Dunstone, Nick J., additional, Scaife, Adam A., additional, Fiedler, Emma K., additional, Copsey, Dan, additional, and Hardiman, Steven C., additional

Published
2018
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21. Examining the West African Monsoon circulation response to atmospheric heating in a GCM dynamical core

Author

Chadwick, Robin, Martin, Gill, Copsey, Dan, Bellon, Gilles, Caian, M., Codron, Francis, Rio, Catherine, Roehrig, Romain, Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office [Exeter], University of Auckland [Auckland], Swedish Meteorological and Hydrological Institute (SMHI), Processus de la variabilité climatique tropicale et impacts (PARVATI), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), European Project: 282672,EC:FP7:ENV,FP7-ENV-2011,EMBRACE(2011), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Climate Research, Klimatforskning
Abstract

International audience Diabatic heating plays a crucial role in the formation and maintenance of the West African Monsoon. A dynamical core configuration of a General Circulation Model (GCM) is used to test the influence of diabatic heating from different sources and regions on the strength and northward penetration of the monsoon circulation. The dynamical core is able to capture the main features of the monsoon flow, and when forced with heating tendencies from various different GCMs it recreates many of the differences seen between the full GCM monsoon circulations. Differences in atmospheric shortwave absorption over the Sahara and Sahel regions are a key driver of variation in the models' monsoon circulations, and this is likely to be linked to how aerosols, clouds and surface albedo are represented across the models. The magnitude of shortwave absorption also appears to affect the strength and position of the African easterly jet (AEJ), but not that of the tropical easterly jet (TEJ). The dynamical core is also used here to understand circulation changes that occur during the ongoing model development process that occurs at each modeling centre, providing the potential to trace these changes to specific alterations in model physics.

Published
2017
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22. The Met Office Unified Model Global Atmosphere 6.0/6.1 and JULES Global Land 6.0/6.1 configurations

Author

Walters, David, primary, Boutle, Ian, additional, Brooks, Malcolm, additional, Melvin, Thomas, additional, Stratton, Rachel, additional, Vosper, Simon, additional, Wells, Helen, additional, Williams, Keith, additional, Wood, Nigel, additional, Allen, Thomas, additional, Bushell, Andrew, additional, Copsey, Dan, additional, Earnshaw, Paul, additional, Edwards, John, additional, Gross, Markus, additional, Hardiman, Steven, additional, Harris, Chris, additional, Heming, Julian, additional, Klingaman, Nicholas, additional, Levine, Richard, additional, Manners, James, additional, Martin, Gill, additional, Milton, Sean, additional, Mittermaier, Marion, additional, Morcrette, Cyril, additional, Riddick, Thomas, additional, Roberts, Malcolm, additional, Sanchez, Claudio, additional, Selwood, Paul, additional, Stirling, Alison, additional, Smith, Chris, additional, Suri, Dan, additional, Tennant, Warren, additional, Vidale, Pier Luigi, additional, Wilkinson, Jonathan, additional, Willett, Martin, additional, Woolnough, Steve, additional, and Xavier, Prince, additional

Published
2017
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23. The impact of resolving the Rossby radius at mid-latitudes in the ocean: results from a high-resolution version of the Met Office GC2 coupled model

Author

Hewitt, Helene T., Roberts, Malcolm J., Hyder, Pat, Graham, Tim, Rae, Jamie, Belcher, Stephen E., Bourdallé-Badie, Romain, Copsey, Dan, Coward, Andrew, Guiavarch, Catherine, Harris, Chris, Hill, Richard, Hirschi, Joël J.-M., Madec, Gurvan, Mizielinski, Matthew S., Neininger, Erica, New, Adrian L., Rioual, Jean-Christophe, Sinha, Bablu, Storkey, David, Shelly, Ann, Thorpe, Livia, Wood, Richard A., Hewitt, Helene T., Roberts, Malcolm J., Hyder, Pat, Graham, Tim, Rae, Jamie, Belcher, Stephen E., Bourdallé-Badie, Romain, Copsey, Dan, Coward, Andrew, Guiavarch, Catherine, Harris, Chris, Hill, Richard, Hirschi, Joël J.-M., Madec, Gurvan, Mizielinski, Matthew S., Neininger, Erica, New, Adrian L., Rioual, Jean-Christophe, Sinha, Bablu, Storkey, David, Shelly, Ann, Thorpe, Livia, and Wood, Richard A.

Abstract

There is mounting evidence that resolving mesoscale eddies and western boundary currents as well as topographically controlled flows can play an important role in air–sea interaction associated with vertical and lateral transports of heat and salt. Here we describe the development of the Met Office Global Coupled Model version 2 (GC2) with increased resolution relative to the standard model: the ocean resolution is increased from 1/4 to 1/12° (28 to 9 km at the Equator), the atmosphere resolution increased from 60 km (N216) to 25 km (N512) and the coupling period reduced from 3 hourly to hourly. The technical developments that were required to build a version of the model at higher resolution are described as well as results from a 20-year simulation. The results demonstrate the key role played by the enhanced resolution of the ocean model: reduced sea surface temperature (SST) biases, improved ocean heat transports, deeper and stronger overturning circulation and a stronger Antarctic Circumpolar Current. Our results suggest that the improvements seen here require high resolution in both atmosphere and ocean components as well as high-frequency coupling. These results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.

Published
2016

24. The impact of resolving the Rossby radius at mid-latitudes in the ocean: results from a high-resolution version of the Met Office GC2 coupled model

Author

Hewitt, Helene T., primary, Roberts, Malcolm J., additional, Hyder, Pat, additional, Graham, Tim, additional, Rae, Jamie, additional, Belcher, Stephen E., additional, Bourdallé-Badie, Romain, additional, Copsey, Dan, additional, Coward, Andrew, additional, Guiavarch, Catherine, additional, Harris, Chris, additional, Hill, Richard, additional, Hirschi, Joël J.-M., additional, Madec, Gurvan, additional, Mizielinski, Matthew S., additional, Neininger, Erica, additional, New, Adrian L., additional, Rioual, Jean-Christophe, additional, Sinha, Bablu, additional, Storkey, David, additional, Shelly, Ann, additional, Thorpe, Livia, additional, and Wood, Richard A., additional

Published
2016
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25. The Met Office Unified Model Global Atmosphere 6.0/6.1 and JULES Global Land 6.0/6.1 configurations

Author

Walters, David, primary, Brooks, Malcolm, additional, Boutle, Ian, additional, Melvin, Thomas, additional, Stratton, Rachel, additional, Vosper, Simon, additional, Wells, Helen, additional, Williams, Keith, additional, Wood, Nigel, additional, Allen, Thomas, additional, Bushell, Andrew, additional, Copsey, Dan, additional, Earnshaw, Paul, additional, Edwards, John, additional, Gross, Markus, additional, Hardiman, Steven, additional, Harris, Chris, additional, Heming, Julian, additional, Klingaman, Nicholas, additional, Levine, Richard, additional, Manners, James, additional, Martin, Gill, additional, Milton, Sean, additional, Mittermaier, Marion, additional, Morcrette, Cyril, additional, Riddick, Thomas, additional, Roberts, Malcolm, additional, Sanchez, Claudio, additional, Selwood, Paul, additional, Stirling, Alison, additional, Smith, Chris, additional, Suri, Dan, additional, Tennant, Warren, additional, Vidale, Pier Luigi, additional, Wilkinson, Jonathan, additional, Willett, Martin, additional, Woolnough, Steve, additional, and Xavier, Prince, additional

Published
2016
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26. Supplementary material to "The Met Office Unified Model Global Atmosphere 6.0/6.1 and JULES Global Land 6.0/6.1 configurations"

Author

Walters, David, primary, Brooks, Malcolm, additional, Boutle, Ian, additional, Melvin, Thomas, additional, Stratton, Rachel, additional, Vosper, Simon, additional, Wells, Helen, additional, Williams, Keith, additional, Wood, Nigel, additional, Allen, Thomas, additional, Bushell, Andrew, additional, Copsey, Dan, additional, Earnshaw, Paul, additional, Edwards, John, additional, Gross, Markus, additional, Hardiman, Steven, additional, Harris, Chris, additional, Heming, Julian, additional, Klingaman, Nicholas, additional, Levine, Richard, additional, Manners, James, additional, Martin, Gill, additional, Milton, Sean, additional, Mittermaier, Marion, additional, Morcrette, Cyril, additional, Riddick, Thomas, additional, Roberts, Malcolm, additional, Sanchez, Claudio, additional, Selwood, Paul, additional, Stirling, Alison, additional, Smith, Chris, additional, Suri, Dan, additional, Tennant, Warren, additional, Vidale, Pier Luigi, additional, Wilkinson, Jonathan, additional, Willett, Martin, additional, Woolnough, Steve, additional, and Xavier, Prince, additional

Published
2016
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29. The Met Office Unified Model Global Atmosphere 6.0/6.1 and JULES Global Land 6.0/6.1 configurations.

Author

Walters, David, Brooks, Malcolm, Boutle, Ian, Melvin, Thomas, Stratton, Rachel, Vosper, Simon, Wells, Helen, Williams, Keith, Wood, Nigel, Allen, Thomas, Bushell, Andrew, Copsey, Dan, Earnshaw, Paul, Edwards, John, Gross, Markus, Hardiman, Steven, Harris, Chris, Heming, Julian, Klingaman, Nicholas, and Levine, Richard

Subjects
LAND surface temperature, ATMOSPHERIC pressure, WEATHER forecasting
Abstract

We describe Global Atmosphere 6.0 and Global Land 6.0: the latest science configurations of the Met Office Unified Model and JULES land surface model developed for use across all timescales. Global Atmosphere 6.0 includes the ENDGame dynamical core, which significantly increases mid-latitude variability improving a known model bias. Alongside developments of the model's physical parametrisations, ENDGame also increases variability in the tropics, which leads to an improved representation of tropical cyclones and other tropical phenomena. Further developments of the atmospheric and land surface parametrisations improve other aspects of model performance, including the forecasting of surface weather phenomena. We also describe Global Atmosphere 6.1 and Global Land 6.1, which include a small number of long-standing differences from our main trunk configurations that we continue to require for operational global weather prediction. Since July 2014, GA6.1/GL6.1 has been used by the Met Office for operational global NWP, whilst GA6.0/GL6.0 was implemented in its remaining global prediction systems over the following year. [ABSTRACT FROM AUTHOR]

Published
2016
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30. Improved Atlantic winter blocking in a climate model

Author

Scaife, Adam A., primary, Copsey, Dan, additional, Gordon, Chris, additional, Harris, Chris, additional, Hinton, Tim, additional, Keeley, Sarah, additional, O'Neill, Alan, additional, Roberts, Malcolm, additional, and Williams, Keith, additional

Published
2011
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33. Tropical cyclone sensitivity to nearby convection. How convection tuning can improve forecasts of hurricanes Jose and Irma in a coupled NWP model.

Author

Copsey, Dan

Subjects
*HURRICANE forecasting, *HURRICANE Irma, 2017, *HURRICANES
Abstract

We test the sensitivity of the track forecast of hurricanes Jose and Irma to tuning of the convection scheme in coupled ocean-atmosphere forecasts using the Met Office UM model. Both hurricanes occurred in the Western Atlantic basin in September 2017. The track of hurricane Jose included an anti-cyclonic loop, which was poorly simulated by the Met Office forecast. We will show that by tuning the convection scheme to remove unrealistic deep convection to the West of the storm it improves the projected track. In contrast, the track of Hurricane Irma remained further south and was well forecast by the Met Office UM model but the forecast deteriorates when convection is modified with the same tunings as applied to Jose. In this case reducing the deep convection leads to a reduction in the strength of the subtropical high. We will present results of further tuning of the convection scheme to retain the good performance for Jose without deteriorating the performance of Irma and extend the testing to other storms during the 2017 hurricane season. [ABSTRACT FROM AUTHOR]

Published
2019

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