the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Oct 2023
An Overview of the E3SM version 2 Large Ensemble and Comparison to other E3SM and CESM Large Ensembles
Abstract. This work assesses a recently produced 21-member climate model large ensemble (LE) based on the U.S. Department of Energy’s Energy Exascale Earth System Model (E3SM) version 2 (E3SM2). The ensemble spans the historical era (1850 to 2014) and 21st Century (2015 to 2100), using the SSP370 pathway, allowing for an evaluation of the model’s forced response (FR). A companion 500-year preindustrial control simulation is used to initialize the ensemble and estimate drift. Characteristics of the LE are documented and compared against other recently produced ensembles using the E3SM version 1 (E3SM1) and Community Earth System Model (CESM) versions 1 and 2.
Simulation drift is found to be smaller, and model agreement with observations is higher, in versions 2 of E3SM and CESM versus their version 1 counterparts. Shortcomings in E3SM2 include a lack of warming from the mid to late 20th Century likely due to excessive cooling influence of anthropogenic sulfate aerosols, an issue also evident in E3SM1. Associated impacts on the water cycle and energy budgets are also identified. Considerable model dependence in the FR associated with both aerosol and greenhouse gas responses is documented and E3SM2’s sensitivity to variable prescribed biomass burning emissions is demonstrated.
Various E3SM2 and CESM2 model benchmarks are found to be on par with the highest performing recent generation of climate models, establishing the E3SM2 LE as an important resource for estimating climate variability and responses, though with various caveats as discussed herein. As an illustration of the usefulness of LEs in estimating the potential influence of internal variability, the observed CERES-era trend in net top-of-atmosphere flux is compared to simulated trends and found to be much larger than the FR in all LEs, with only a few members exhibiting trends as large as observed, thus motivating further study.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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(1704 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-2310', Anonymous Referee #1, 20 Nov 2023
This paper examines 4 LEs for many metrics regarding the forced response. It is well written, the science is sound and I recommend for publication after minor revisions.
Minor comments:
Abstract - FR is confusing in the abstract - I recommend spelling it out in this section
45/46 - needs citations. Here are possibilities: https://esd.copernicus.org/articles/12/401/2021/ OR https://www.nature.com/articles/s41558-020-0731-2.epdf?author_access_token=OnhiIlhZkm3p58t3OHjV3tRgN0jAjWel9jnR3ZoTv0NnBpoO0B2TlXC-0PoMuTZLSw6_YFL5sMa_yz8wJSmNsSAiVurA3amG421TAO0symp2l6aSmTSddEE13z7RMtzL7vdbK7d6lErsCSwQhQgY9Q%3D%3D
Introduction - this is very short. It could include another paragraph on studies looking at FR in LEs - there are quite a few of these that could easily be discussed
92 CESM2 is not yet introduced
Section 2.5.1 and 2.5.2 what is the observational uncertainty? This should be stated and/or included in the figures
Table 1 - in the title can you explain what is in the table please? It is unclear what each metric means
192 - how long a record of CERES would be needed to resolve this
314 though should be although
328 is 1 a maximum score? There is not enough detail for the reader to interpret this without reading the cited manuscript
Conclusions - lastly is there twice
The conclusions should be explaned to talk about future ideas as per the EGUSphere guidelines. Some of this could be as simple as expanding the analysis to all avaiable LEs
Citation: https://doi.org/10.5194/egusphere-2023-2310-RC1 -
AC1: 'Reply on RC1', John Fasullo, 04 Jan 2024
[our replies to reviewer comments are included in bold below]
This paper examines 4 LEs for many metrics regarding the forced response. It is well written, the science is sound and I recommend for publication after minor revisions.
Thanks for the time spent reviewing our work and for your constructive comments.
Minor comments:
Abstract - FR is confusing in the abstract - I recommend spelling it out in this section.
Agreed – it is now spelled out.
45/46 - needs citations. Here are possibilities: https://esd.copernicus.org/articles/12/401/2021/ OR https://www.nature.com/articles/s41558-020-0731-2.epdf?author_access_token=OnhiIlhZkm3p58t3OHjV3tRgN0jAjWel9jnR3ZoTv0NnBpoO0B2TlXC-0PoMuTZLSw6_YFL5sMa_yz8wJSmNsSAiVurA3amG421TAO0symp2l6aSmTSddEE13z7RMtzL7vdbK7d6lErsCSwQhQgY9Q%3D%3D
Agreed. Thanks for the suggestions. These are important citations to include and we have added a few others.
Introduction - this is very short. It could include another paragraph on studies looking at FR in LEs - there are quite a few of these that could easily be discussed
Agreed. We have now expanded the introduction to include mention of various references above to illustrate the diverse contexts in which the FR has been examined using LEs.
92 CESM2 is not yet introduced
Good catch. We’ve moved this statement to the CESM2 section.
Section 2.5.1 and 2.5.2 what is the observational uncertainty? This should be stated and/or included in the figures
By including multiple temperature datasets in Fig. 2, which are characteristic generally of inter-dataset disagreements, we have made an effort to address observational uncertainties. Given that the CERES values are already a challenge to see in Fig 3, due to their brevity, and depend on context (absolute values vs drift), we’d prefer to mention these uncertainties in the data section rather than add additional time series to Fig. 2.
Table 1 - in the title can you explain what is in the table please? It is unclear what each metric means
Good point, as these metrics are likely to be unfamiliar to most readers. Text has been added to provide a general overview of the metrics and their significance.
192 - how long a record of CERES would be needed to resolve this
It is not quite clear what needs to be “resolved” here but perhaps the reviewer is suggesting that this statement should be expanded to account for observational uncertainty. We have expanded it to address this.
314 though should be although
Thanks, changed.
328 is 1 a maximum score? There is not enough detail for the reader to interpret this without reading the cited manuscript
Agreed that more detail is needed. Context has been added to this section to make it clearer to readers that are unfamiliar with the package.
Conclusions - lastly is there twice
Good catch. Revised.
The conclusions should be explaned to talk about future ideas as per the EGUSphere guidelines. Some of this could be as simple as expanding the analysis to all avaiable LEs
Text has been added to provide this perspective on future efforts.
Citation: https://doi.org/10.5194/egusphere-2023-2310-AC1
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AC1: 'Reply on RC1', John Fasullo, 04 Jan 2024
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RC2: 'Comment on egusphere-2023-2310', Anonymous Referee #2, 20 Nov 2023
The authors described the E3SM2 LE and compared it with the other 3 LEs. This paper is well written and would be useful for users of the output data of these LEs. Although the excessive aerosol cooling in the 20th century is unfortunate, I hope that the authors would fix this problem in a future work. I recommend publication after a minor revision.
Minor comments.
*Fig 3c: Why do the top-of-model net radiation flux in the Southern Hemisphere has negative trends in the 21st century for E3SM1 and E3SM2?
*It is better for readers to note whether positive values of MHTatm and MHTocn are northward or southward.
Citation: https://doi.org/10.5194/egusphere-2023-2310-RC2 -
AC2: 'Reply on RC2', John Fasullo, 04 Jan 2024
[Our responses indicated in bold below.]
The authors described the E3SM2 LE and compared it with the other 3 LEs. This paper is well written and would be useful for users of the output data of these LEs. Although the excessive aerosol cooling in the 20th century is unfortunate, I hope that the authors would fix this problem in a future work. I recommend publication after a minor revision.
Thank you for your effort reviewing our work and for your constructive comments. Indeed, a successive version of E3SM that reduces biases in simulated aerosol-cloud interactions is planned, along with a large ensemble based on it. We now mention this in the conclusions.
Minor comments.
*Fig 3c: Why do the top-of-model net radiation flux in the Southern Hemisphere has negative trends in the 21st century for E3SM1 and E3SM2?
Good question. We now highlight these unexpected trends and include an expanded discussion of the potential drivers. We find that both E3SM1 and 2 have such flat trends in the 21st Century in RT for different reasons. In E3SM1 the RT trends are flat because OLR and temperature trends in the SH are stronger than in the other ensembles (and thus offset albedo reductions). In v2 the flat trend is because shortwave (SWTOA) trends are weaker than in the other ensembles and are thus fully offset by OLR trends, which are in line with the other ensembles. This in turn contributes to a slower rate of warming in the SH.
*It is better for readers to note whether positive values of MHTatm and MHTocn are northward or southward.
Good point. Now defined.
Citation: https://doi.org/10.5194/egusphere-2023-2310-AC2
-
AC2: 'Reply on RC2', John Fasullo, 04 Jan 2024
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-2310', Anonymous Referee #1, 20 Nov 2023
This paper examines 4 LEs for many metrics regarding the forced response. It is well written, the science is sound and I recommend for publication after minor revisions.
Minor comments:
Abstract - FR is confusing in the abstract - I recommend spelling it out in this section
45/46 - needs citations. Here are possibilities: https://esd.copernicus.org/articles/12/401/2021/ OR https://www.nature.com/articles/s41558-020-0731-2.epdf?author_access_token=OnhiIlhZkm3p58t3OHjV3tRgN0jAjWel9jnR3ZoTv0NnBpoO0B2TlXC-0PoMuTZLSw6_YFL5sMa_yz8wJSmNsSAiVurA3amG421TAO0symp2l6aSmTSddEE13z7RMtzL7vdbK7d6lErsCSwQhQgY9Q%3D%3D
Introduction - this is very short. It could include another paragraph on studies looking at FR in LEs - there are quite a few of these that could easily be discussed
92 CESM2 is not yet introduced
Section 2.5.1 and 2.5.2 what is the observational uncertainty? This should be stated and/or included in the figures
Table 1 - in the title can you explain what is in the table please? It is unclear what each metric means
192 - how long a record of CERES would be needed to resolve this
314 though should be although
328 is 1 a maximum score? There is not enough detail for the reader to interpret this without reading the cited manuscript
Conclusions - lastly is there twice
The conclusions should be explaned to talk about future ideas as per the EGUSphere guidelines. Some of this could be as simple as expanding the analysis to all avaiable LEs
Citation: https://doi.org/10.5194/egusphere-2023-2310-RC1 -
AC1: 'Reply on RC1', John Fasullo, 04 Jan 2024
[our replies to reviewer comments are included in bold below]
This paper examines 4 LEs for many metrics regarding the forced response. It is well written, the science is sound and I recommend for publication after minor revisions.
Thanks for the time spent reviewing our work and for your constructive comments.
Minor comments:
Abstract - FR is confusing in the abstract - I recommend spelling it out in this section.
Agreed – it is now spelled out.
45/46 - needs citations. Here are possibilities: https://esd.copernicus.org/articles/12/401/2021/ OR https://www.nature.com/articles/s41558-020-0731-2.epdf?author_access_token=OnhiIlhZkm3p58t3OHjV3tRgN0jAjWel9jnR3ZoTv0NnBpoO0B2TlXC-0PoMuTZLSw6_YFL5sMa_yz8wJSmNsSAiVurA3amG421TAO0symp2l6aSmTSddEE13z7RMtzL7vdbK7d6lErsCSwQhQgY9Q%3D%3D
Agreed. Thanks for the suggestions. These are important citations to include and we have added a few others.
Introduction - this is very short. It could include another paragraph on studies looking at FR in LEs - there are quite a few of these that could easily be discussed
Agreed. We have now expanded the introduction to include mention of various references above to illustrate the diverse contexts in which the FR has been examined using LEs.
92 CESM2 is not yet introduced
Good catch. We’ve moved this statement to the CESM2 section.
Section 2.5.1 and 2.5.2 what is the observational uncertainty? This should be stated and/or included in the figures
By including multiple temperature datasets in Fig. 2, which are characteristic generally of inter-dataset disagreements, we have made an effort to address observational uncertainties. Given that the CERES values are already a challenge to see in Fig 3, due to their brevity, and depend on context (absolute values vs drift), we’d prefer to mention these uncertainties in the data section rather than add additional time series to Fig. 2.
Table 1 - in the title can you explain what is in the table please? It is unclear what each metric means
Good point, as these metrics are likely to be unfamiliar to most readers. Text has been added to provide a general overview of the metrics and their significance.
192 - how long a record of CERES would be needed to resolve this
It is not quite clear what needs to be “resolved” here but perhaps the reviewer is suggesting that this statement should be expanded to account for observational uncertainty. We have expanded it to address this.
314 though should be although
Thanks, changed.
328 is 1 a maximum score? There is not enough detail for the reader to interpret this without reading the cited manuscript
Agreed that more detail is needed. Context has been added to this section to make it clearer to readers that are unfamiliar with the package.
Conclusions - lastly is there twice
Good catch. Revised.
The conclusions should be explaned to talk about future ideas as per the EGUSphere guidelines. Some of this could be as simple as expanding the analysis to all avaiable LEs
Text has been added to provide this perspective on future efforts.
Citation: https://doi.org/10.5194/egusphere-2023-2310-AC1
-
AC1: 'Reply on RC1', John Fasullo, 04 Jan 2024
-
RC2: 'Comment on egusphere-2023-2310', Anonymous Referee #2, 20 Nov 2023
The authors described the E3SM2 LE and compared it with the other 3 LEs. This paper is well written and would be useful for users of the output data of these LEs. Although the excessive aerosol cooling in the 20th century is unfortunate, I hope that the authors would fix this problem in a future work. I recommend publication after a minor revision.
Minor comments.
*Fig 3c: Why do the top-of-model net radiation flux in the Southern Hemisphere has negative trends in the 21st century for E3SM1 and E3SM2?
*It is better for readers to note whether positive values of MHTatm and MHTocn are northward or southward.
Citation: https://doi.org/10.5194/egusphere-2023-2310-RC2 -
AC2: 'Reply on RC2', John Fasullo, 04 Jan 2024
[Our responses indicated in bold below.]
The authors described the E3SM2 LE and compared it with the other 3 LEs. This paper is well written and would be useful for users of the output data of these LEs. Although the excessive aerosol cooling in the 20th century is unfortunate, I hope that the authors would fix this problem in a future work. I recommend publication after a minor revision.
Thank you for your effort reviewing our work and for your constructive comments. Indeed, a successive version of E3SM that reduces biases in simulated aerosol-cloud interactions is planned, along with a large ensemble based on it. We now mention this in the conclusions.
Minor comments.
*Fig 3c: Why do the top-of-model net radiation flux in the Southern Hemisphere has negative trends in the 21st century for E3SM1 and E3SM2?
Good question. We now highlight these unexpected trends and include an expanded discussion of the potential drivers. We find that both E3SM1 and 2 have such flat trends in the 21st Century in RT for different reasons. In E3SM1 the RT trends are flat because OLR and temperature trends in the SH are stronger than in the other ensembles (and thus offset albedo reductions). In v2 the flat trend is because shortwave (SWTOA) trends are weaker than in the other ensembles and are thus fully offset by OLR trends, which are in line with the other ensembles. This in turn contributes to a slower rate of warming in the SH.
*It is better for readers to note whether positive values of MHTatm and MHTocn are northward or southward.
Good point. Now defined.
Citation: https://doi.org/10.5194/egusphere-2023-2310-AC2
-
AC2: 'Reply on RC2', John Fasullo, 04 Jan 2024
Peer review completion
Journal article(s) based on this preprint
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Jean-Christophe Golaz
Julie Caron
Nan Rosenbloom
Gerald Meehl
Warren Strand
Sasha Glanville
Samantha Stevenson
Maria Molina
Christine Shields
Chengzhu Zhang
James Benedict
Tony Bartoletti
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(7986 KB) - Metadata XML
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Supplement
(1704 KB) - BibTeX
- EndNote
- Final revised paper