Effect of high dust amount on surface temperature during the Last Glacial Maximum: a modelling study using MIROC-ESM

Ohgaito, Rumi; Abe-Ouchi, Ayako; O'ishi, Ryouta; Takemura, Toshihiko; Ito, Akinori; Hajima, Tomohiro; Watanabe, Shingo; Kawamiya, Michio

doi:https://doi.org/10.5194/cp-14-1565-2018

Articles | Volume 14, issue 11

https://doi.org/10.5194/cp-14-1565-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Paleoclimate Modelling Intercomparison Project phase 4 (PMIP4)...

https://doi.org/10.5194/cp-14-1565-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 11

Research article

|

01 Nov 2018

Research article |

| 01 Nov 2018

Effect of high dust amount on surface temperature during the Last Glacial Maximum: a modelling study using MIROC-ESM

Rumi Ohgaito, Ayako Abe-Ouchi, Ryouta O'ishi, Toshihiko Takemura, Akinori Ito, Tomohiro Hajima, Shingo Watanabe, and Michio Kawamiya

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Final revised paper (published on 01 Nov 2018)
Supplement to the final revised paper
Preprint (discussion started on 21 Feb 2018)

Interactive discussion

Status: closed

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

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RC1: 'Interesting study, but needs better link to past work and more detail on methods', Anonymous Referee #1, 06 Mar 2018
- AC1: 'Response to the referee #1', Rumi Ohgaito, 13 Jul 2018
RC2: 'Referee comments', Anonymous Referee #2, 09 Mar 2018
- AC2: 'Response to the referee #2', Rumi Ohgaito, 13 Jul 2018

Peer-review completion

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

ED: Reconsider after major revisions (16 Jul 2018) by Masa Kageyama

AR by Rumi Ohgaito on behalf of the Authors (16 Jul 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Jul 2018) by Masa Kageyama

RR by Anonymous Referee #2 (01 Aug 2018)

RR by Anonymous Referee #1 (31 Aug 2018)

Suggestions for revision or reasons for rejection

I realise figures 6 & 7 were in the first submission, but I think they need the LGM.a – PI.a anomalies. This would make it consistent with figures 2-5 and 9-12 and the rest of the paper. It would also help to redress the emphasis from analysing the glaciogenic effect alone, to a more general paper about LGM dust, which is what the introduction leads the reader to expect, and which was commented on by the other reviewer in the first round. This would also make sense given the artificial nature of the glaciogenic dust inputs used.
I now realise I don’t understand the difference between Figure 10 (Change of net radiative perturbation by dust at the surface) and figure 7 (Change in (a) net, (b) longwave, and (c) shortwave downward radiation at the surface).
Page 13, lines 13-19: Is there a longwave aerosol-cloud effect in the northern hemisphere also? E.g. looking at figure 7b or 10e? Otherwise, I don’t understand why this only occurs in the southern hemisphere. From figure 7c and 7a, is it possible that in the northern hemisphere it is offset by a short-wave effect, hence it doesn’t show up in figure C?
Technical comments

Abstract, line 15: remove ‘found’.

Page 2, line 7: “Global warming is considered an important driver in investigations seeking to clarify the mechanisms of climate change, as stated repeatedly by the Intergovernmental Panel on Climate Change (IPCC) in their assessment reports (IPCC, 2013).”

This doesn’t really make sense. Perhaps change to:

“Global climate modelling is an essential tool in investigations seeking to clarify the mechanisms of climate change, as stated in Intergovernmental Panel on Climate Change (IPCC) assessment reports (IPCC, 2013).”
Page 4, line 15: Make this sentence more direct. Change: “Previous studies that have investigated the effect of glaciogenic dust have not taken into account the feedback of the dust to the atmosphere via the oceanic thermohaline circulation. “ to highlight something like: previous studies have included a dynamic ocean in this context, so the impacts on ocean circulation globally are unknown.
Page 4, line 16: Move this sentence: “Moreover, Lambert et al. (2013) identified the possibility of polar amplification attributable to dust.” to earlier where you discuss polar amplification, and explain what Lambert did in 1 sentence or so.
Page 6, line 9: Change “and it was emitted constantly independent of the other conditions “, to “The fluxes estimated by Mahowald were added as time-invariant sources into the simulations, and are not dependent on modelled land surface or atmospheric conditions”.
Page 12, line 19: “The panels clarify that the effect of snow ageing on the radiative perturbation is minor.”
This sentence seems to contradict the results shown in figure 6 and the discussion starting on page 10 line 18?

Page 14, line 15-16: You might mention that some of this model-data disagreement is related to reconstructed warming in Alaska, which is not resolved in either LGM or LGMglac.

Page 17, line 3: I don’t think Claquin et al 2003, looked at snow albedo effect of dust?
Page 17, line 5-7. To support this statement, you need to include the LGMglac.a – PI.a anomaly in figure 6.

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ED: Publish subject to minor revisions (review by editor) (18 Sep 2018) by Masa Kageyama

AR by Rumi Ohgaito on behalf of the Authors (28 Sep 2018) Author's response Manuscript

ED: Publish subject to technical corrections (12 Oct 2018) by Masa Kageyama

The new manuscript is largely improved and the comments from the reviewers have been thoroughly taken into account. The manuscript is therefore good for publications after the following minor corrections (page numbering from the authors’s response to the reviewers, with manuscript starting on page 7).
Minor corrections.
1. Introduction
page 8, line 1: was => is
page 9, line 2: remove comma after “i.e.”
page 10, lines 2-4: reformulate the sentence, for instance: Lambert et al. (2013) used two General Circulation Models coupled with online aerosol models and obtained underestimated dust flux and radiative forcing. This underestimation was global, but more pronounced over the polar regions and they suggested the possibility that it contributes to an underestimation of polar amplification for LGM and future projections.
page 10, line 5: supposed => defined
page 10, line 12: during => for (the LGM) and in => for (the PI)
page 11, line 2: addressed => addresses
2. Model and experimental design
2.1: description of the MIROC-ESM
page 11 lines 13-14: “prognosis of” => computing
page 12, line 7: insert commas before and after “as their mass mixing ratios”
page 12, line 18: replace “weighted to” by “weighted as a function of”
2.2 Experimental design
page 13, line 13: please insert Fig A of the supplementary material in the main text.
3. Results
3.1 Dust amount and comparison with data archives
page 14 (and page 13, line 15 and 16). The tables are not listed in order
page 15, line 2: “but the load (38 Tg) is significantly smaller (62Tg)”. Please clarify 38Thg is smaller than 62 Tg, and it is difficult to know which load corresponds to which simulation.
3.2 Surface temperature at LGM and the effect of glaciogenic dust
page 16, line 5: latitude => latitudes
page 16, line 5, insert “most” before “promnounced”
page 16, line 7: insert “results in” after “LGM” and replace “in consistent distribution to” by “and is consistent with the distribution of”
page 16, line 14: I think the reference is to Figure 7g, not 7c
page 17, line 6: please inset Fig B from supplementary material in main manuscript
page 17, line 11: the reference to Krinner is missing; replace “on the point of” by “about”
page 17, line 13: isopleth => isotherm
3.3 aerosol-radiation and aerosol-cloud interactions by dust
page 18, section title: would “dust-related aerosol-radiation and aerosol-cloud interactions” be better?
page 18, line 3: add “including dust impacts” after “standard experiment”?
page 18, line 5: clarification is needed here: is the aerosol-cloud interaction estimated with the comparison of the standard experiment with another experiment without dust at all? or without dust in the cloud radiation package?
page 18, line 10: insert “results from” before “previous studies”
page 19, line 16: insert “due to dust” after “perturbation”
3.4 influence of glaciogenic dust on the ocean
page 20, lines 16-17: the sentence “The different behaviour … LGMglac.e.” can eb removed, as the idea is developed later in that section.
page 21, line 8: insert “for LGMglac.e compard to LGM.e” after “increased air temperature”

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AR by Rumi Ohgaito on behalf of the Authors (17 Oct 2018) Author's response Manuscript

Short summary

The behaviour of dust in terms of climate can be investigated using past climate. The Last Glacial Maximum (LGM; 21000 years before present) is known to be dustier. We investigated the impact of plausible dust distribution on the climate of the LGM using an Earth system model and found that the higher dust load results in less cooling over the polar regions. The main finding is that radiative perturbation by the high dust loading does not necessarily cool the surface surrounding Antarctica.