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2. The HadGEM3‐GC3.1 Contribution to the CMIP6 Detection and Attribution Model Intercomparison Project.

Author

Jones, Gareth S., Andrews, Martin B., Andrews, Timothy, Blockley, Ed, Ciavarella, Andrew, Christidis, Nikos, Cotterill, Daniel F., Lott, Fraser C., Ridley, Jeff, and Stott, Peter A.

Subjects
*CLIMATE change detection, *CLIMATE change models, *ATMOSPHERIC models, *ATMOSPHERIC temperature, *ATMOSPHERIC boundary layer
Abstract

The UK contribution to the Detection and Attribution Model Intercomparison Project (DAMIP), part of the sixth phase of the Climate Model Intercomparison Project (CMIP6), is described. The lower atmosphere and ocean resolution configuration of the latest Hadley Centre global environmental model, HadGEM3‐GC3.1, is used to create simulations driven either with historical changes in anthropogenic well‐mixed greenhouse gases, anthropogenic aerosols, or natural climate factors. Global mean near‐surface air temperatures from the HadGEM3‐GC31‐LL simulations are consistent with CMIP6 model ensembles for the equivalent experiments. While the HadGEM3‐GC31‐LL simulations with anthropogenic and natural forcing factors capture the overall observed warming, the lack of marked simulated warming until the 1990s is diagnosed as due to aerosol cooling mostly offsetting the well‐mixed greenhouse gas warming until then. The model has unusual temperature variability over the Southern Ocean related to occasional deep convection bringing heat to the surface. This is most prominent in the model's aerosol only simulations, which have the curious feature of warming in the high southern latitudes, while the rest of the globe cools, a behavior not seen in other CMIP6 models. This has implications for studies that assume model responses, from different climate drivers, can be linearly combined. While DAMIP was predominantly designed for detection and attribution studies, the experiments are also very valuable for understanding how different climate drivers influence a model, and thus for interpretating the responses of combined anthropogenic and natural driven simulations. We recommend institutions provide model simulations for the high priority DAMIP experiments. Plain Language Summary: We describe the UK submission to the Detection and Attribution Model Intercomparison Project (DAMIP), using the HadGEM3‐GC3.1 climate model. The model's near‐surface temperature responses to different human and natural climate drivers are compared with other climate models and observed temperature changes. The experiments help to understand the evolution of the model's simulated historical global temperatures. One of the more interesting model features is the variability in the Southern Ocean which manifests itself as occasional surface warming due to deep ocean heat coming to the surface. This behavior, which occurs more often in simulations that cool than in simulations that warm, appears to be unusual compared to other models. The investigation of this model behavior demonstrates that DAMIP model experiments are not just useful for climate change detection and attribution, but also for understanding how a model responds to different climate drivers. Climate model participation in DAMIP is encouraged. Key Points: The UK's contribution to the Detection and Attribution Model Intercomparison project (DAMIP) is describedThe climate model's global temperature response to different anthropogenic and natural drivers is examined and compared to other modelsSouthern Ocean temperature variability is unusual and sensitive to climate driver [ABSTRACT FROM AUTHOR]

Published
2024
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5. Statistics of sudden stratospheric warmings using a large model ensemble.

Author

Ineson, Sarah, Dunstone, Nick J., Scaife, Adam A., Andrews, Martin B., Lockwood, Julia F., and Pang, Bo

Subjects
EL Nino, LA Nina, SEASONS, POLAR vortex
Abstract

Using a large ensemble of initialised retrospective forecasts (hindcasts) from a seasonal prediction system, we explore various statistics relating to sudden stratospheric warmings (SSWs). Observations show that SSWs occur at a similar frequency during both El Niño and La Niña northern hemisphere winters. This is contrary to expectation, as the stronger stratospheric polar vortex associated with La Niña years might be expected to result in fewer of these extreme breakdowns. Here we show that this similar frequency may have occurred by chance due to the limited sample of years in the observational record. We also show that in these hindcasts, winters with two SSWs, a rare event in the observational record, on average have an increased surface impact. Multiple SSW events occur at a lower rate than expected if events were independent but somewhat surprisingly, our analysis also indicates a risk, albeit small, of winters with three or more SSWs, as yet an unseen event. [ABSTRACT FROM AUTHOR]

Published
2024
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7. QBO Phase Synchronization in CMIP6 Historical Simulations Attributed to Ozone Forcing.

Author

Butchart, Neal, Andrews, Martin B., and Jones, Chris D.

Subjects
*OZONE, *ZONAL winds, *SYNCHRONIZATION, *STRATOSPHERE, *QUASI-biennial oscillation (Meteorology), *CLIMATE change, *OZONE layer
Abstract

Tropical stratospheric variability is investigated in ensembles of historical simulations performed by nine models for the sixth phase of the Coupled Model Intercomparison Project (CMIP6). Realizations from all the models feature a reasonable quasi‐biennial oscillation (QBO). Variability in the zonal mean zonal winds at the equator is found to be coherent among realizations when a model prescribes the CMIP6 ozone forcing. No such coherence is found when a model simulates ozone. The coherence results in an ensemble mean QBO signal with amplitude, depending on the model, 50%–80% of the mean QBO amplitude from a single realization from the same model. The ensemble mean signal is due to synchronization of QBO phases, attributed to the CMIP6 protocol including a QBO signal in the ozone forcing. Coherence in models using the CMIP6 ozone is, therefore, artificial and individual realizations from these models are not completely independent. Plain Language Summary: High above the equator winds in the stratosphere at altitudes from ∼16–40 km repeatedly switch direction from eastward to westward, and back again, roughly every 14 months. This so‐called quasi‐biennial oscillation (QBO) featured in only a subset of the simulations of the historical period that provided input for the latest international assessments of climate change. Variability in the stratospheric winds at the equator in these simulations is found to be remarkably coherent across ensembles of realizations from the individual models, but only for those models that did not simulate ozone variability. Instead, these models followed a common protocol that specified prescribing an ozone distribution that included a QBO in the tropical stratosphere. For each of the models this causes the simulated QBOs in the winds to synchronize across many realizations of the historical period. Consequently variability in the equatorial stratosphere in these realizations becomes coherent. However, this coherence is not real as it is merely an artifact of the simulations following the agreed ozone protocol. Likewise, due to the design of the protocol, individual realizations from these models can not be considered as been entirely independent in the tropical stratosphere. Key Points: Coupled Model Intercomparison Project phase 6 (CMIP6) historical simulations from several models feature a realistic quasi‐biennial oscillation (QBO) in the equatorial stratosphereQBO phases synchronize across ensembles of realizations from models not able to simulate evolving ozoneThe phase synchronization is artificial and attributed to the CMIP6 protocol prescribing a QBO signal in the ozone forcing data [ABSTRACT FROM AUTHOR]

Published
2023
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10. Assessing the representation of South American monsoon features in Brazil and U.K. climate model simulations

Author

Coelho, Caio A. S., primary, Souza, Dayana C., additional, Kubota, Paulo Y., additional, Cavalcanti, Iracema F. A., additional, Baker, Jessica C. A., additional, Figueroa, Silvio N., additional, Firpo, Mári A. F., additional, Guimarães, Bruno S., additional, Costa, Simone M. S., additional, Gonçalves, Layrson J. M., additional, Bonatti, José P., additional, Sampaio, Gilvan, additional, Klingaman, Nicholas P., additional, Chevuturi, Amulya, additional, and Andrews, Martin B., additional

Published
2021
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11. The Brewer–Dobson circulation in CMIP6

Author

Abalos, Marta, primary, Calvo, Natalia, additional, Benito-Barca, Samuel, additional, Garny, Hella, additional, Hardiman, Steven C., additional, Lin, Pu, additional, Andrews, Martin B., additional, Butchart, Neal, additional, Garcia, Rolando, additional, Orbe, Clara, additional, Saint-Martin, David, additional, Watanabe, Shingo, additional, and Yoshida, Kohei, additional

Published
2021
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12. Description and evaluation of aerosol in UKESM1 and\ud HadGEM3-GC3.1 CMIP6 historical simulations

Author

Mulcahy, Jane P., Johnson, Colin, Jones, Colin G., Povey, Adam C., Scott, Catherine E., Sellar, Alistair, Turnock, Steven T., Woodhouse, Matthew T., Abraham, N. Luke, Andrews, Martin B., Bellouin, Nicolas, Browse, Jo, Carslaw, Ken S., Dalvi, Mohit, Folberth, Gerd A., Glover, Matthew, Grosvenor, Daniel, Hardacre, Catherine, Hill, Richard, Johnson, Ben, Jones, Andy, Kipling, Zak, Mann, Graham, Mollard, James, O'Connor, Fiona M., Palmieri, Julien, Reddington, Carly, Rumbold, Steven T., Richardson, Mark, Schutgens, Nick A.J., Stier, Philip, Stringer, Marc, Tang, Yongming, Walton, Jeremy, Woodward, Stephanie, and Yool, Andrew

Subjects
respiratory system, complex mixtures
Abstract

We document and evaluate the aerosol schemes as implemented in the physical and Earth system models, HadGEM3-GC3.1 (GC3.1) and UKESM1, which are contributing to the 6th Coupled Model Intercomparison Project (CMIP6). The simulation of aerosols in the present-day period of the historical ensemble of these models is evaluated against a range of observations. Updates to the aerosol microphysics scheme are documented as well as differences in the aerosol representation between the physical and Earth system configurations. The additional Earth-system interactions included in UKESM1 leads to differences in the emissions of natural aerosol sources such as dimethyl sulfide, mineral dust and organic aerosol and subsequent evolution of these species in the model. UKESM1 also includes a stratospheric-tropospheric chemistry scheme which is fully coupled to the aerosol scheme, while GC3.1 employs a simplified aerosol chemistry mechanism driven by prescribed monthly climatologies of the relevant oxidants. Overall, the simulated speciated aerosol mass concentrations compare reasonably well with observations. Both models capture the negative trend in sulfate aerosol concentrations over Europe and the eastern United States of America (US) although the models tend to underestimate the sulfate concentrations in both regions. Interactive emissions of biogenic volatile organic compounds in UKESM1 lead to an improved agreement of organic aerosol over the US. Simulated dust burdens are similar in both models despite a 2-fold difference in dust emissions. Aerosol optical depth is biased low in dust source and outflow regions but performs well in other regions compared to a number of satellite and ground-based retrievals of aerosol optical depth. Simulated aerosol number concentrations are generally within a factor of 2\ud of the observations with both models tending to overestimate number concentrations over remote ocean regions, apart from at high latitudes, and underestimate over Northern Hemisphere continents. Finally, a new primary marine organic aerosol source is implemented in UKESM1 for the first time. The impact of this new aerosol source is evaluated. Over the pristine Southern Ocean, it is found to improve the seasonal cycle of organic aerosol mass and cloud droplet number concentrations relative to GC3.1 although underestimations in cloud droplet number concentrations remain. This paper provides a useful characterization of the aerosol climatology in both models facilitating the understanding of the numerous aerosol-climate interaction studies that will be conducted as part of CMIP6 and beyond.

Published
2020

13. Description and evaluation of aerosol in UKESM1 and HadGEM3-GC3.1 CMIP6 historical simulations

Author

Mulcahy, Jane P., primary, Johnson, Colin, additional, Jones, Colin G., additional, Povey, Adam C., additional, Scott, Catherine E., additional, Sellar, Alistair, additional, Turnock, Steven T., additional, Woodhouse, Matthew T., additional, Abraham, Nathan Luke, additional, Andrews, Martin B., additional, Bellouin, Nicolas, additional, Browse, Jo, additional, Carslaw, Ken S., additional, Dalvi, Mohit, additional, Folberth, Gerd A., additional, Glover, Matthew, additional, Grosvenor, Daniel P., additional, Hardacre, Catherine, additional, Hill, Richard, additional, Johnson, Ben, additional, Jones, Andy, additional, Kipling, Zak, additional, Mann, Graham, additional, Mollard, James, additional, O'Connor, Fiona M., additional, Palmiéri, Julien, additional, Reddington, Carly, additional, Rumbold, Steven T., additional, Richardson, Mark, additional, Schutgens, Nick A. J., additional, Stier, Philip, additional, Stringer, Marc, additional, Tang, Yongming, additional, Walton, Jeremy, additional, Woodward, Stephanie, additional, and Yool, Andrew, additional

Published
2020
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15. Historical Simulations With HadGEM3‐GC3.1 for CMIP6

Author

Andrews, Martin B., primary, Ridley, Jeff K., additional, Wood, Richard A., additional, Andrews, Timothy, additional, Blockley, Edward W., additional, Booth, Ben, additional, Burke, Eleanor, additional, Dittus, Andrea J., additional, Florek, Piotr, additional, Gray, Lesley J., additional, Haddad, Stephen, additional, Hardiman, Steven C., additional, Hermanson, Leon, additional, Hodson, Dan, additional, Hogan, Emma, additional, Jones, Gareth S., additional, Knight, Jeff R., additional, Kuhlbrodt, Till, additional, Misios, Stergios, additional, Mizielinski, Matthew S., additional, Ringer, Mark A., additional, Robson, Jon, additional, and Sutton, Rowan T., additional

Published
2020
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16. Implementation of U.K. Earth System Models for CMIP6

Author

Sellar, Alistair A., primary, Walton, Jeremy, additional, Jones, Colin G., additional, Wood, Richard, additional, Abraham, Nathan Luke, additional, Andrejczuk, Miroslaw, additional, Andrews, Martin B., additional, Andrews, Timothy, additional, Archibald, Alex T., additional, de Mora, Lee, additional, Dyson, Harold, additional, Elkington, Mark, additional, Ellis, Richard, additional, Florek, Piotr, additional, Good, Peter, additional, Gohar, Laila, additional, Haddad, Stephen, additional, Hardiman, Steven C., additional, Hogan, Emma, additional, Iwi, Alan, additional, Jones, Christopher D., additional, Johnson, Ben, additional, Kelley, Douglas I., additional, Kettleborough, Jamie, additional, Knight, Jeff R., additional, Köhler, Marcus O., additional, Kuhlbrodt, Till, additional, Liddicoat, Spencer, additional, Linova‐Pavlova, Irina, additional, Mizielinski, Matthew S., additional, Morgenstern, Olaf, additional, Mulcahy, Jane, additional, Neininger, Erica, additional, O'Connor, Fiona M., additional, Petrie, Ruth, additional, Ridley, Jeff, additional, Rioual, Jean‐Christophe, additional, Roberts, Malcolm, additional, Robertson, Eddy, additional, Rumbold, Steven, additional, Seddon, Jon, additional, Shepherd, Harry, additional, Shim, Sungbo, additional, Stephens, Ag, additional, Teixiera, Joao C., additional, Tang, Yongming, additional, Williams, Jonny, additional, Wiltshire, Andy, additional, and Griffiths, Paul T., additional

Published
2020
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17. Supplementary material to "Description and evaluation of aerosol in UKESM1 and HadGEM3-GC3.1 CMIP6 historical simulations"

Author

Mulcahy, Jane P., primary, Johnson, Colin, additional, Jones, Colin G., additional, Povey, Adam C., additional, Scott, Catherine E., additional, Sellar, Alistair, additional, Turnock, Steven T., additional, Woodhouse, Matthew T., additional, Abraham, N. Luke, additional, Andrews, Martin B., additional, Bellouin, Nicolas, additional, Browse, Jo, additional, Carslaw, Ken S., additional, Dalvi, Mohit, additional, Folberth, Gerd A., additional, Glover, Matthew, additional, Grosvenor, Daniel, additional, Hardacre, Catherine, additional, Hill, Richard, additional, Johnson, Ben, additional, Jones, Andy, additional, Kipling, Zak, additional, Mann, Graham, additional, Mollard, James, additional, O'Connor, Fiona M., additional, Palmieri, Julien, additional, Reddington, Carly, additional, Rumbold, Steven T., additional, Richardson, Mark, additional, Schutgens, Nick A. J., additional, Stier, Philip, additional, Stringer, Marc, additional, Tang, Yongming, additional, Walton, Jeremy, additional, Woodward, Stephanie, additional, and Yool, Andrew, additional

Published
2020
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19. UKESM1: Description and Evaluation of the U.K. Earth System Model

Author

Sellar, Alistair A., primary, Jones, Colin G., additional, Mulcahy, Jane P., additional, Tang, Yongming, additional, Yool, Andrew, additional, Wiltshire, Andy, additional, O'Connor, Fiona M., additional, Stringer, Marc, additional, Hill, Richard, additional, Palmieri, Julien, additional, Woodward, Stephanie, additional, Mora, Lee, additional, Kuhlbrodt, Till, additional, Rumbold, Steven T., additional, Kelley, Douglas I., additional, Ellis, Rich, additional, Johnson, Colin E., additional, Walton, Jeremy, additional, Abraham, Nathan Luke, additional, Andrews, Martin B., additional, Andrews, Timothy, additional, Archibald, Alex T., additional, Berthou, Ségolène, additional, Burke, Eleanor, additional, Blockley, Ed, additional, Carslaw, Ken, additional, Dalvi, Mohit, additional, Edwards, John, additional, Folberth, Gerd A., additional, Gedney, Nicola, additional, Griffiths, Paul T., additional, Harper, Anna B., additional, Hendry, Maggie A., additional, Hewitt, Alan J., additional, Johnson, Ben, additional, Jones, Andy, additional, Jones, Chris D., additional, Keeble, James, additional, Liddicoat, Spencer, additional, Morgenstern, Olaf, additional, Parker, Robert J., additional, Predoi, Valeriu, additional, Robertson, Eddy, additional, Siahaan, Antony, additional, Smith, Robin S., additional, Swaminathan, Ranjini, additional, Woodhouse, Matthew T., additional, Zeng, Guang, additional, and Zerroukat, Mohamed, additional

Published
2019
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20. Forcings, Feedbacks, and Climate Sensitivity in HadGEM3‐GC3.1 and UKESM1

Author

Andrews, Timothy, primary, Andrews, Martin B., additional, Bodas‐Salcedo, Alejandro, additional, Jones, Gareth S., additional, Kuhlbrodt, Till, additional, Manners, James, additional, Menary, Matthew B., additional, Ridley, Jeff, additional, Ringer, Mark A., additional, Sellar, Alistair A., additional, Senior, Catherine A., additional, and Tang, Yongming, additional

Published
2019
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21. The Impact of Prescribed Ozone in Climate Projections Run With HadGEM3‐GC3.1

Author

Hardiman, Steven C., primary, Andrews, Martin B., additional, Andrews, Timothy, additional, Bushell, Andrew C., additional, Dunstone, Nick J., additional, Dyson, Harold, additional, Jones, Gareth S., additional, Knight, Jeff R., additional, Neininger, Erica, additional, O'Connor, Fiona M., additional, Ridley, Jeff K., additional, Ringer, Mark A., additional, Scaife, Adam A., additional, Senior, Catherine A., additional, and Wood, Richard A., additional

Published
2019
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22. Data for publication, 'Observed and simulated teleconnections between the stratospheric Quasi-Biennial Oscillation and Northern Hemisphere winter atmospheric circulation'

Author

Andrews, Martin B.

Abstract

This data relates to the publication, 'Observed and simulated teleconnections between the stratospheric Quasi-Biennial Oscillation and Northern Hemisphere winter atmospheric circulation' in JGR-Atmospheres, submitted 2018. It consists of data produced by a HadGEM3-GC2 piControl run. The purpose of the publication is to explore the relationship between the QBO and the winter northern hemisphere atmospheric circulation. The data consists of the following: MSLP dataset. See attributes in netcdf file for more info. QBO index at 15 hPa. See attributes in netcdf file for more info. QBO index at 30 hPa. See attributes in netcdf file for more info. &nbsp

Published
2018
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25. Preindustrial Control Simulations With HadGEM3‐GC3.1 for CMIP6

Author

Menary, Matthew B., primary, Kuhlbrodt, Till, additional, Ridley, Jeff, additional, Andrews, Martin B., additional, Dimdore‐Miles, Oscar B., additional, Deshayes, Julie, additional, Eade, Rosie, additional, Gray, Lesley, additional, Ineson, Sarah, additional, Mignot, Juliette, additional, Roberts, Christopher D., additional, Robson, Jon, additional, Wood, Richard A., additional, and Xavier, Prince, additional

Published
2018
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