Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores

Döring, Michael; Leuenberger, Markus C.

doi:https://doi.org/10.5194/cp-14-763-2018

Articles | Volume 14, issue 6

https://doi.org/10.5194/cp-14-763-2018

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

Special issue:

“Global Challenges for our Common Future: a paleoscience perspective”...

https://doi.org/10.5194/cp-14-763-2018

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

Articles | Volume 14, issue 6

Research article

|

12 Jun 2018

Research article |

| 12 Jun 2018

Novel automated inversion algorithm for temperature reconstruction using gas isotopes from ice cores

Michael Döring and Markus C. Leuenberger

Download

Final revised paper (published on 12 Jun 2018)
Supplement to the final revised paper
Preprint (discussion started on 17 Jul 2017)
Supplement to the preprint

Interactive discussion

Status: closed

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

- Printer-friendly version

- Supplement

RC1: 'Getting temperature from d15N data', Anonymous Referee #1, 17 Jul 2017
- AC1: 'Reply to the review of Anonymous Referee #1', Michael Döring, 08 Sep 2017
SC1: 'Novelty of the inversion method presented by Döring and Leuenberger', Myriam Guillevic, 27 Jul 2017
RC2: 'Review of "Novel approach for ice core based temperature reconstructions - a synthetic data study for Holocene δ15N data"', Anonymous Referee #2, 07 Aug 2017
- AC2: 'Reply to the review of Anonymous Referee #2', Michael Döring, 08 Sep 2017
SC2: 'Data Review Team Comment', PAGES Data Review Team, 27 Aug 2017
- AC3: 'Reply to the PAGES Data Review Team comment:', Michael Döring, 08 May 2018

Peer-review completion

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

ED: Reconsider after major revisions (21 Sep 2017) by Emily Dearing Crampton Flood

AR by Michael Döring on behalf of the Authors (25 Oct 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Nov 2017) by Emily Dearing Crampton Flood

RR by Anonymous Referee #1 (03 Nov 2017)

Suggestions for revision or reasons for rejection

It needs to be made clear, right at the beginning, that d15N by itself is not sufficient to provide a temperature record. There must be a highly accurate independent accumulation rate record in addition. It is only the COMBINATION of d15N data and accumulation data that gives temperature, in the method that is described in the manuscript. The reason is very simple. A doubling of accumulation rate can cause a change in firn thickness and hence d15N, with no temperature change whatsoever.

The same is true for d40Ar data, when it is used as the sole gas measurement.

Highly accurate d15Nexcess data, however, can provide a temperature record without any associated accumulation record. This distinction needs to be made clearer. In its present form the reader could be seriously misled by the manuscript. It borders on scientific dishonesty to persist in making this misleading presentation of the facts.

page 4 line 16 units for mass difference should be "kg per mol"

page 4 line 27 the language here is confusing. As I understand it, the Leuenberger, Boersma-Klein, and DeVries results were not the ones used in the current manuscript, so there is no place for them in the sentence describing the given equation. Please cut the mention of Leuenberger and Boersma-Klein and DeVries, as it makes it hard for the reader to know which measurement result is being presented in the given equation. There should be no ambiguity here, and there is indeed no excuse for creating ambiguity in a scientific paper. This issue was already raised by one of the reviewers in the first round of review, and the authors have apparently chosen to ignore that reviewer. This is unacceptable and unprofessional behavior and the authors are hereby warned that continuing to ignore the reviewers will result in rejection of the manuscript.

Hide

RR by Anonymous Referee #3 (15 Jan 2018)

ED: Reconsider after major revisions (30 Jan 2018) by Emily Dearing Crampton Flood

AR by Michael Döring on behalf of the Authors (02 Mar 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (06 Mar 2018) by Emily Dearing Crampton Flood

RR by Anonymous Referee #1 (19 Mar 2018)

Suggestions for revision or reasons for rejection

Minor revisions required prior to publication: (if the authors do not make these corrections, the paper must be considered subject to major revisions and returned to the reviewers for another round of review)

On page 4, line 18: add Orsi et al. 2014 after Kindler et al. 2014

On page 4, line 34: the statement is made that, except for the spin-up, the method is completely independent of water isotopes. If this is really the case, why is the spin-up needed at all? It seems to me that your statement would be more accurate if you said something like "the method is mostly independent of water isotopes." It would also be useful to add a graph in the Supplement showing the resulting temperature histories when a water isotope spin-up was, and was not, used. That would give the reader a feeling for how independent the method really is.

On page 5, line 8: The argument is made that because both 15N and 40Ar are used, there is no possibility to compare one solution against the other. This statement is rather misleading. In fact, the reason that both isotope pairs were used by Orsi et al. was to eliminate the gravitational signal from the data, which substantially reduces the uncertainty in the final derived temperature. When using only one isotope pair, the uncertainty is much larger, due to the need to match the gravitational signal accurately. Unfortunately, the gravitational signal is affected by many non-temperature processes, such as changes in the convective zone thickness, imperfections in the accumulation data accuracy, imperfections in the firn thickness model, and uncertainties in the true lock-in density. These additional uncertainties amount to 2-3 deg C of extra uncertainty in many real-world cases (for example, see Kobashi et al. 2008)

In summary, the use of only one isotope pair is highly inferior to the use of two; and saying that it is an advantage to be able to compare one to the other is like saying that "half of a bicycle is better than a whole bicycle because it is possible to compare the performance of the rider when riding only the front wheel, with the performance of the rider when riding only the back wheel."

This sentence must therefore be cut prior to publication. Instead, the authors could say something like "The method presented here can be used when no 40Ar data are available, which is often the case because 40Ar is a more analytically challenging measurement and is not as commonly measured as 15N."

Page 13, line 7: the word "synchronicity" should be replaced with "synchroneity". Synchronicity is a term from Jungian psychology, and I do not think the authors intended this meaning.

Page 29, line 4: The convective zone (CZ) does not include a non-diffusive zone. In fact there is molecular diffusion occurring in the CZ; it is simply overwhelmed by mixing due to convection. I suggest you replace the words "non-diffusive zone" with "well-mixed zone".

The authors are thanked for their close attention to my prior comments.

Hide

ED: Publish subject to minor revisions (review by editor) (03 Apr 2018) by Emily Dearing Crampton Flood

AR by Michael Döring on behalf of the Authors (05 Apr 2018) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (16 Apr 2018) by Emily Dearing Crampton Flood

AR by Michael Döring on behalf of the Authors (30 Apr 2018) Author's response Manuscript

ED: Publish as is (12 May 2018) by Emily Dearing Crampton Flood

AR by Michael Döring on behalf of the Authors (15 May 2018)

Short summary

We present a novel approach for ice-core-based temperature reconstructions, which is based on gas-isotope data measured on enclosed air bubbles in ice cores. The processes of air movement and enclosure are highly temperature dependent due to heat diffusion in and densification of the snow and ice. Our method inverts a model, which describes these processes, to desired temperature histories. This paper examines the performance of our novel approach on different synthetic isotope-data scenarios.