the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
High resolution aerosol data from the top 3.8 ka of the EGRIP ice core
Camilla Marie Jensen
Florian Adolphi
Helle Astrid Kjær
Remi Dallmayr
Birthe Twarloh
Melanie Behrens
Motohiro Hirabayashi
Kaori Fukuda
Jun Ogata
François Burgay
Federico Scoto
Ilaria Crotti
Azzurra Spagnesi
Niccoló Maffezzoli
Delia Segato
Chiara Paleari
Florian Mekhaldi
Raimund Muscheler
Sophie Darfeuil
Hubertus Fischer
Abstract. Here we present the high-resolution CFA data from the top 479 m of the East Greenland Ice coring Project (EGRIP) ice core covering the past 3.8 thousand years. The data consists of 1 mm-depth-resolution profiles of calcium, sodium, am- monium, nitrate and electrolytic conductivity as well as decadal averages of these profiles. Alongside the data we provide a description of the measurement setup, procedures, the relevant references for the specific methods as well as an assessment of the precision of the measurements, the sample to depth assignment and the depth and temporal resolution of the data set. The nominally 1-mm data represents an oversampling of the record as the true resolution is limited by the analytical setup to approximately 1 cm. The error of absolute depth assignment of the data may be on the order of 1 cm, however relative depth offsets be- tween the records of the individual species is only on the order of 1 mm. The presented data has sub-annual resolution over the entire depth range and has already formed part of the data for an annually layer-counted time scale for the EGRIP ice core used to improve and revise the multi-core Greenland ice-core chronology (GICC05) to a new version,GICC21 (Sinnl et al., 2021). The data is available in full 1-mm resolution and decadal averages on PANGAEA (https://doi.org/10.1594/PANGAEA.945293 (Erhardt et al., 2022b))
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Tobias Erhardt et al.
Status: final response (author comments only)
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RC1: 'Comment on essd-2023-176', Anonymous Referee #1, 03 Jul 2023
This paper describes a dataset, deposited at Pangaea, that contains high-resolution (1 mm) CFA data for ions (and conductivity) from EGRIP. The data extend to 3800 years (479 m); they have been used to develop an age model so far; they are clearly supporting data for that and therefore have value, as well as future value for assessing changes in environmental factors over this time period. Much of the paper itself is devoted to describing methodology. This includes more general methodology about the drilling and CFA campaign (which also generated other data not shown here). The main novelty in the methodology compared to previous data papers concerns the ICP-TOFMS. The methodology seems clear and the data are undoubtedly of high quality, so the paper seems very publishable. I note that this is only about half the data that were measured in 2018 and 2019. While I understand why the data are being released in increments, it will be annoying for users if they remain in separate files, so I suggest that future releases are added to existing files rather than listed as separate files that readers have to splice together.
With a few minor corrections and suggestions below, I am happy to recommend publication of this data paper.
Lines 43, 51: accumulation rates are in cm/a – is this water equivalent or ice equivalent?
Fig 2 caption. Sorry to be fussy but the correct abbreviation is mL not ml. Similarly uL later.
Line 83 “samples at 5−−2.5 cm depth” – please explain what you mean by this. Do you mean “between 2.5 and 5 cm”? It’s not obvious.
Lines 84, 86, “aliquots” spelling
Line 113 “Note, that the air is released from the ice during melting and thus does not pose a contamination risk”. I’m not sure what this means, why would the air pose a contamination risk?
Fig 3, line 4 of caption “most”
Fig 3 – for comparison purposes it would be better if the y-scaling of the two Ca datasets was the same, which seems not to be the case at present.
Line 202 “mis-measurement” spelling
Section 5.2 and Fig 5. I found this section hard to follow. Please spell out what you mean by “encoder deviation” in 5G – it seems from the text as if it should be telling me about the “total discrepancy between the length of ice as measured by the encoder to the length of ice measured using sample preparation” but I don’t understand what you mean by this “encoder deviation”. Also if its 1% (typically) for a 3 m piece, how is the depth precise to 1 cm? I believe you that it is, but I’m not clear how I get that from Figure 5. The figure is also not well-designed if you aim to show that run length doesn’t affect the depth precision, as it is impossible to follow the few shorter runs down to section G.
Line 239. Figure 7 is called before Figure 6. You may want to renumber them?
Line 241 “deposition” spelling
Line 244 “88CE, corresponding to 1910 yr b2k” – am I missing something? Surely 88CE is 1912 b2k?
Line 303 “Here we…”
Citation: https://doi.org/10.5194/essd-2023-176-RC1 - AC1: 'Author comment for essd-2023-176', Tobias Erhardt, 29 Aug 2023
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RC2: 'Comment on essd-2023-176', Anonymous Referee #2, 05 Jul 2023
Erhardt and others present a multi-species dataset of aerosol records measured from the EastGRIP ice core (top 479 meters). The record being discussed covers the past 3,800 years and has a temporal resolution on sub-annual scale. Overall, the authors did a good job in describing the samples, the analytical methods, and the product dataset. I only have a few number questions that revolve around the clarity of the manuscript and a handful of technical comments/suggestions. Once they are addressed, I will be happy to recommend the acceptance of this manuscript.
Line 6: here you acknowledge that the 1-mm-resolution dataset is an oversampling of the true record and the actual resolution is probably 1-cm. It would be better if you could move this sentence to line 3, right after “as well as decadal averages of these profiles.” Otherwise, people might start calculating the temporal resolution themselves and apparently overestimate the temporal resolution by an order of magnitude.
Line 10: there should be a blank in front of “GICC21”.
Line 23: ‘gold standard’ is a pretty strong statement. Can you add some citations to this sentence to back it up?
Line 44-45: it would be nice to note that the drilling is still ongoing as of writing (btw I enjoy reading the field diary!).
Line 51: can you add a very quick description how Gerber et al (2021) derived those numbers (111 km further upstream and 160 m higher)?
Line 58 (as well as line 97 below): the description here seems to suggest that the introduction of the ICP-TOFMS occurred between 2018 and 2019. Yet, looking at the data it appears that the ICP-TOFMS has been there all along; it’s just the absorption method for Na+ was discontinued in 2019 and the data produced in this method were not included in the PANGEA dataset. Is this the case? If so, you might want to re-word some sections or, if space permits, have a separate table documenting what methods measured what properties in what year (or in what depth range), and whether those data are included in your dataset.
Line 83: the ‘5 − −2.5 cm’ expression seems strange and not very clear. Please consider rephrasing.
Line 97 and onward: I recommend you discuss ICP-TOFMS exclusively in section 4.2.
Line 140: here you mentioned the presence of large gaps in the Ca2+ data but didn’t explain why (except briefing doing so in the caption of Figure 3 and explaining the LOD issue in line 179). It would be better if you could succinctly describe the analytical issues that led to those gaps here so readers will better understand the possible limitations of the dataset.
Line 288: could you please elaborate how the potentially contaminated ice is removed, like by extensive trimming perhaps?
Line 292: this section (5.5) doesn’t seem to affect data quality directly but concerns the interpretation of the data, which is not what this manuscript aims to do. Maybe this section can be moved towards the beginning of the manuscript (in section 2 for example).
Citation: https://doi.org/10.5194/essd-2023-176-RC2 - AC1: 'Author comment for essd-2023-176', Tobias Erhardt, 29 Aug 2023
- AC1: 'Author comment for essd-2023-176', Tobias Erhardt, 29 Aug 2023
Tobias Erhardt et al.
Tobias Erhardt et al.
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