Mid-to-late Holocene temperature evolution and atmospheric dynamics over Europe in regional model simulations

Russo, Emmanuele; Cubasch, Ulrich

doi:https://doi.org/10.5194/cp-12-1645-2016

Articles | Volume 12, issue 8

https://doi.org/10.5194/cp-12-1645-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/cp-12-1645-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 12, issue 8

Research article

|

17 Aug 2016

Research article |

| 17 Aug 2016

Mid-to-late Holocene temperature evolution and atmospheric dynamics over Europe in regional model simulations

Emmanuele Russo and Ulrich Cubasch

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Final revised paper (published on 17 Aug 2016)
Supplement to the final revised paper
Preprint (discussion started on 02 Feb 2016)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review of the article by Russo and Cubasch', Anonymous Referee #1, 08 Feb 2016
- AC2: 'Reply to 2nd Reviewer', Emmanuele Russo, 11 Apr 2016
SC1: 'There are more RCM simulations of mid-to-late Holocene climate in Europe', Gustav Strandberg, 12 Feb 2016
- AC1: 'Reply to interactive comment by G.Strandberg', Emmanuele Russo, 24 Mar 2016
RC2: 'Review of Russo and Cubasch', Anonymous Referee #2, 24 Feb 2016
- AC3: 'Reply to the 1st reviewer', Emmanuele Russo, 11 Apr 2016

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (12 Apr 2016) by Hugues Goosse

AR by Emmanuele Russo on behalf of the Authors (21 May 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 May 2016) by Hugues Goosse

RR by Anonymous Referee #1 (22 Jun 2016)

Suggestions for revision or reasons for rejection

I have been asked to review an updated version of the manuscript. I have to acknowledge that the authors have made a remarkable effort to accommodate most of my critics and have addressed them rather satisfactorily, including my suggestions for deeper analyses.

I still can identify few minor issues that could be rather easily corrected to improve the manuscript.

As in the former version of the manuscript, there is an excess of too short paragraphs that could be merged to produce a more cohesive text. Examples of this are the first three paragraphs (that have not been merged despite my recommendation), lines 82-83, 143-145, 227-228, 258-259, 312-322, the four paragraphs between lines 347 and 366, and the two between 411 and 415, and finally even in the acknowledgements, which I'd merge into one single paragraph.

In section 2 I think it would be clearer if method and different dataset are described in separate subsections. Something like 2.1 Models, 2.2 Observations, 2.3 Reconstructions, or something similar.

In the discussion of the model performance, in page 7, I think the discussion should be more quantitative, providing more numbers drwn from the corresponding figures that quantify the disagreements that are being discussed. In this regard, it would be interesting to provide also numbers drawn from similar exercises in the literature, so it can be quantitatively argued how the errors are indeed within the margins "acceptable".

In Fig. 6, the anomalies are calculated over which period? Only one year, or are they averages over 10 years or longer?

In the discussion of Figure 6, it us argued that the warm bias in the North is present in the reconstructions, which happen in all models but in ECHO-G. However the figure is not shown. I think this is a quite important finding, and I'd advise the authors to reconsider showing the figure that is mentioned, because it's the only that can supports that rather important claim.

I think Tables 2 and 3 should be merged.

Although the text is clearer, I found several mistakes or expressions that I do not think are very standard. However, I didn't review this aspect of the manuscript extensively since as I understand this will be eventually tackled at a latter stage by professional text reviewers prior final publication, which surely will amend these small mistakes and many other I could not possibly spot.

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RR by Anonymous Referee #2 (24 Jun 2016)

Suggestions for revision or reasons for rejection

Compared to the previous version, this version has much improved. For instance, in my view, the comparison of the CCLM results with ECHAM5, including the application of the cost function, has strengthened the manuscript considerably. However, there are still several points that must be addressed before this manuscript can be considered for publication.

Concerning my first main comment in the previous review, I find that the manuscript is still rather poorly written. It still includes many language mistakes, so I am quite sure that the text has not been checked by a native speaker as I suggested. Such a check would significantly improve the readability of the manuscript, so I stress this issue once more here.

Furthermore, regarding my 5th previous comment, the authors have not really provided a more in-depth discussion of the uncertainty of the summer temperature reconstructions for Southern Europe. In addition, their reply to my comment is not clear to me on this point. The authors note that "the previous analyses of mid-to-late Holocene temperature evolution were misleading. In fact, simply considering regional means, they did not allow to have a proper overview of the trends at different locations, possibly resulting in a mismatch in the comparison against other proxies. The new maps presented in Fig. 4 show now a more heterogeneous behaviour, and are in better agreement with other indipendent reconstructions". From the reply, it is not clear who "they" are, or what "previous analyses" the authors are referring to. Furthermore, Figure 4 presents maps of summer temperatures for the period 1991-2000, so not for the mid-to-late Holocene. A major outcome of the present paper is the mismatch between the CCLM model results in Southern Europe and the pollen-based reconstructions of Mauri et al. (2014), showing an opposite trends in summer. In Mauri et al. (2014), the pollen-based reconstruction is compared against independent reconstructions (their Figure 8), but this was not done for summer temperatures in Southern Europe, except for the Alps. In explaining the noted mismatch, Russo and Cubasch only consider a model bias in surface heat fluxes, but do not reflect on the possibility that the pollen-based reconstruction does not capture the right temperature trend in the Mediterranean area during the Holocene. The latter possibility has been discussed in the literature before as I mentioned in my review of the CPD manuscript, and I urge the authors again to make the readers aware of this discussion. As mentioned in Section 3.3.1., all PMIP3 models suggest warmer conditions in Southern Europe during the mid-Holocene (see also Table S2), so if the reconstruction of Mauri et al. (2014) is correctly indicating cooler conditions here, this implies that all these models are not capable of capturing the right climate response in Southern Europe under influence of astronomical forcing. An alternative to consider is that the reconstructions are incorrect. This important issue is still under debate, and in my opinion it is crucial to provide the arguments of both sides of this debate.

Minor comments:

Line 157: It is mentioned here that effects of greenhouse gas forcing is not considered in the analyses. Does this mean that the trace gas concentrations were kept fixed at their preindustrial values in all experiments? Or are the concentrations adjusted in the experiments based on ice-core measurements, but is the effect of this forcing not separated from the impact of insolation changes? Please clarify.

Line 195: Please explain what you mean by 'satisfactory results'.

Lines 213 and 219: Why do you use "instead" in these sentences?

Line 219 to 228: I suggest to make this section more quantitative, as it is very descriptive.

Section 3.3.1: This new section on the results of PMIP3 experiments is a useful addition to the manuscript. However, it is very descriptive and it could be made more informative by making it more quantitative.

Line 270: I suggest to use "proxy-based reconstructions", as the proxies themselves are not reconstructed.

Line 281: "The coastline is also better reproduced in this case, resulting in more suitable informations for possible comparison against proxy-data". Please clarify how a more detailed coastline would improve the model-data comparison. See also line 448 in the Conclusions.

Line 283: "CCLM shows better defined patterns as a consequence of higher resolution". What kind of patterns, please clarify. See also line 449 in the conclusions.

Line 287: Zhang et al. (2010) is missing in the reference list.

Line 306: "It is important to mention that the scale considered in our analysis is closer to the resolution of ECHAM5 than the one of the CCLM". What scale are you referring to here? The scale of the reconstructions?

Line 347: In Fig 9 the winter map for CCLM is gray (i.e. the trend is not significant) in Scandinavia, where the reconstructions show a strong, significant cooling trend. So here the model results do not match the proxy data, and I suggest to mention this here.

Line 387: "the first CCA pair (Fig. 11 a,b)". Is this correct? The MSLP pattern explaining most of the variance is shown in Fig. 11c, so should Fig 11c,d not be the first CCA pair?

Line 409: "to capture this trend". What trend? In soil moisture during Summer? Or in winter or spring precipitation. Please clarify.

Figure 1: In the caption, a reference for the presented data should be added.

Caption Figure 5: Typo, "refernce period"

Figure 6: I suggest to use the same projection in all six panels to facilitate the inter-model comparison.

Figure 9: Please clarify what the unit of the slopes. Is it in °C per 6kyr? Or °C per kyr?

Figure 12: In my view, this figure does not add much to the manuscript, so it could be described only, or it could be moved to the supplementary information.

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ED: Publish subject to minor revisions (review by Editor) (24 Jun 2016) by Hugues Goosse

AR by Emmanuele Russo on behalf of the Authors (04 Jul 2016) Author's response Manuscript

ED: Publish subject to technical corrections (29 Jul 2016) by Hugues Goosse

Dear Authors,

Thanks for the submission of the revised version of your manuscript. The manuscript has been much improved, following the suggestions of the reviewers. I am thus pleased to accept it for publication in Climate of the Past. Nevertheless, some sections are still difficult to read. I just have made some suggestions below but additional ones are expected at the copy editing stage.

Best regards

Hugues Goosse

All the line numbers correspond to the versions with track changes appended to the response to reviewers comments.

Abstract. Line 20. You have modified the text to mention the uncertainties in the reconstructions but the abstract has not been changed (nor the conclusions).

Abstract. Line 22 .’same’ as what ?

Line 43 ‘case study’ instead of ‘case of study’ (see also line 128)

Line 56. ‘Their signal’ refer to reconstructions?

Line 159, Fig ?? (same problem later)

Line 161 ‘60 and 30 latitudes North’ ‘60° and 30° North’ (same caption of Fig. 1).

Line 246. ‘mentioned area ‘ refer to what ?

Line 292. Is ‘data’ the appropriate term ?

Line 294. Is ‘bias' the appropriate term? It usually refers to an error not a just a change?

Line 306. ‘step’ or ‘steps’ ?

Line 307-308. I would suppress ‘Under the mentioned considerations’

Line 345 Would ‘bias’ be better than ‘anomalies’ (as used in line 350)?

Line 355. ‘South’ mean ‘Southern Europe’?

Line 371 ‘their’ instead of ‘thei’

Line ‘424’ ‘explain’ instead of ‘justify’?

Line ‘436’ ‘scarce ability’ does not seem to be the appropriate wording to me.

Line ‘438’ I would join the two paragraphs.

Line ‘442’ Specify a ‘dipole’ between which regions.

Line 446. Why ‘paleohydrological’ while the paper focuses on temperatures ?

Line 471. Again, I would not use ‘bias’ here, rather ‘anomaly’ (same line 480).

Line 478-481. This paragraph corresponds to which season? Should it be merged with the previous paragraph?

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AR by Emmanuele Russo on behalf of the Authors (01 Aug 2016) Author's response Manuscript

Short summary

In this study we use a RCM for three different goals. Proposing a model configuration suitable for paleoclimate studies; evaluating the added value of a regional climate model for paleoclimate studies; investigating temperature evolution of the European continent during mid-to-late Holocene. Results suggest that the RCM seems to produce results in better agreement with reconstructions than its driving GCM. Simulated temperature evolution seems to be too sensitive to changes in insolation.