Seasonal variations in physical characteristics of aerosol particles at the King Sejong Station, Antarctic Peninsula

Kim, Jaeseok; Yoon, Young Jun; Gim, Yeontae; Kang, Hyo Jin; Choi, Jin Hee; Park, Ki-Tae; Lee, Bang Yong

doi:https://doi.org/10.5194/acp-17-12985-2017

Articles | Volume 17, issue 21

https://doi.org/10.5194/acp-17-12985-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-17-12985-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 17, issue 21

Research article

|

03 Nov 2017

Research article |

| 03 Nov 2017

Seasonal variations in physical characteristics of aerosol particles at the King Sejong Station, Antarctic Peninsula

Jaeseok Kim, Young Jun Yoon, Yeontae Gim, Hyo Jin Kang, Jin Hee Choi, Ki-Tae Park, and Bang Yong Lee

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Final revised paper (published on 03 Nov 2017)
Preprint (discussion started on 27 Oct 2016)

Interactive discussion

Status: closed

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

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RC1: 'research paper revision', Anonymous Referee #1, 03 Nov 2016
- AC1: 'Reply to anonymous referee #1', Young Jun YOON, 28 Feb 2017
RC2: 'review of Seasonal variations in physical characteristics of aerosol particles at the King Sejong Station, Antarctic Peninsula', Anonymous Referee #2, 29 Nov 2016
- AC2: 'Reply to anonymous referee #2', Young Jun YOON, 28 Feb 2017

Peer-review completion

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

AR by Young Jun Yoon on behalf of the Authors (28 Feb 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (17 Mar 2017) by Nikos Hatzianastassiou

RR by Anonymous Referee #2 (15 Apr 2017)

RR by Anonymous Referee #4 (04 May 2017)

Suggestions for revision or reasons for rejection

Review of the manuscript entitled “Seasonal variations in physical characteristics of aerosol particles at the King Sejong Station, Antarctic Peninsula” by J. Kim, Y. J. Yoon, Y. Gim, H. J. Kang, J. H. Choi, and B. Y. Lee, with reference no.: acp-2016-795.

This manuscript presents and analyses measurements of aerosol properties (number concentrations, size distributions), cloud condensation nuclei (CCN) and black carbon concentrations for a six-year period (March 2009 to February 2015) at the King Sejong research station in Antarctica.

The Cryosphere and especially Arctic and Antarctica are key components of the Earth’s system, and are inherently sensitive to a changing climate serving as the most stunning indicators of climate change. On the other hand, among climate change drivers, aerosols still contribute the largest uncertainty to the total climate forcing estimate especially through the aerosol – cloud interactions. This is due to the great variety of aerosol types, both natural and anthropogenic, their short atmospheric lifetimes and to the subsequent high spatiotemporal variability of their physical and optical properties. The Antarctic continent being the most remote area on the planet from other continents and thus from anthropogenic activities and emissions, it is an ideal place for studying natural aerosol processes in order to understand them and to correctly distinguish between natural and anthropogenic factors influencing the climate. Apart from some long-range transported pollution aerosols, primary aerosol sources like mineral dust, vegetation, soot or secondary aerosols from gas to particle conversion are virtually absent on this almost completely ice-covered continent. Hence, marine air masses advected from the Southern Ocean surrounding the continent, remains the dominant source to the Antarctic aerosol load. Therefore, any dataset of original and accurate measurements that helps to elucidate physical processes taking place in a such climatically sensitive region is important.

In this framework the submitted manuscript is interesting and relevant to the topics of ACP. Moreover it is well written and organised and thus it could be published in the ACP Journal after taking into account the following comments.

The manuscript presents interesting results on Antarctic aerosols based on continuous relatively long term (six years) observations at King Sejong station. The dataset is unique and the analysis of measurements is quite adequate. Core of the manuscript is data analysis on a seasonal basis and at a next level according to the origin of air masses though timeseries of monthly mean data of some variables are presented (e.g. Fig. 3, Fig. 4, Fig. 7a and Fig. 12). Authors analyse the intra-annual variation of examined parameters and they discuss the main features of their seasonal behavior making an effort to provide possible explanations to interpret their findings. In some cases, they compare their results with that of other research works conducted in Antarctica. However, the whole analysis doesn’t go deeper to gain an important insight into the factors determining the aerosol properties seasonality and the factors affecting the CCN activation. For instance, is the new particle formation the only or the main factor that induces seasonal variation in particle concentration (total and CN2.5)?

My main concern is about the gain of the new knowledge that this paper brings. Authors cite in the text, especially in the introduction, several works on Antarctic aerosols and their properties. So, what is the contribution of this manuscript to this knowledge? In the introduction authors state “Although various studies have been performed, the measurements taken at the Antarctic Peninsula and the long-term observations of aerosol particles are still insufficient” but they do not discuss any inter-annual variability or trend (except for the exceptional year of 2014). Τhey focus on the seasonal variation. In order to support their work, authors should clearly state what are the new approach, analysis and/or findings compared to literature and this should be clearly presented in the concluding section as well. Otherwise, they can discuss their results compared to other works, examining whether they are in agreement strengthening thus the existing knowledge since current results are issued from multi-year observations. Actually they do it sometimes. For instance, authors state that the revealed seasonal pattern of CN2.5 and CN10 is in agreement with the results of previous studies (page 8, lines 8-10). I am wondering if the consideration of the seasonal variation of CN2.5 and CN10 separately, is additional and further information compared to previous works. On the other hand, throughout the discussion regarding timeseries, seasonal behavior of CCN concentrations, particles size distribution and CCN activation ratios, there are no references to other relative studies in Antarctica. If this analysis and its findings give new or additional information should be stated by authors adding thus value to their work. The same is valid for the analysis regarding the effects of air masses origin on the aerosols physical properties.

I should however state that the lack of new knowledge doesn’t reduce the value of a dataset of original measurements of aerosol properties with a relatively long temporal coverage, in a remote, not easily accessible and very interesting from climate change point of view, area of the planet.

Some minor remarks
• Authors give enough information about instrumentation but they do not discuss any quality control assessment that they apply to their raw records.
• Authors trying to interpret the exceptional CN concentration levels during the period 2013-2014, found that air masses origin was differentiating this period compared to previous years. Air masses from south Atlantic were more frequent than other years. A comparison of CN concentration levels with analogous measurements (if there are published) at stations which are affected mostly by south Atlantic air masses could support this argument.
• Analyzing the CCN concentration, it was found that its seasonal variation follows the seasonal cycle of particles concentration which is logical. I have however point out that the CCN concentrations during the period 2013-2014 seem to be unaffected by the low particles concentration in that period as they remain similar to other years.
• Page 3, lines 8-9. In the sentence “…. the direct and indirect climate effects are still unknown (IPCC, 2013).”, I think the word “unknown” is not appropriate. Actually, according to IPCC report, aerosol effects contribute the largest uncertainty in the total radiative forcing. Thus you can replace the word ‘unknown’ by ‘highly uncertain’.
• Page 3, line 21. In the sentence “For these reasons, the observation of the physical properties in Antarctica, …”, replace the word ‘the’ by ‘their’
• Page 7, line 14. In the sentence “Fig. 3 depicts monthly variations of the meteorological parameters measured from and automatic weather system (AWS) …” replace the word ‘and’ by ‘an’
• Page 7, line 18. In the sentence “the observation site was relatively humid and warm condition compared to inland Antarctic stations”, remove the word ‘condition’
• Page 15, line 6. In the sentence “Our results are similar those of previous laboratory and field experiments (Sellegri et al., 2006; Yoon et al., 2007).”, add the word ‘to’ after the word ‘similar’.

Referee Report: PDF

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ED: Reconsider after minor revisions (Editor review) (30 May 2017) by Nikos Hatzianastassiou

AR by Young Jun Yoon on behalf of the Authors (20 Jun 2017)

ED: Reconsider after minor revisions (Editor review) (01 Aug 2017) by Nikos Hatzianastassiou

Dear authors,

thank you for your efforts to revise the manuscript and for your responses to the Reviewers' comments.

Most of the comments and concerns have been addressed. There are only few minor points, as listed below, which need to be clarified and corrected before the final acceptance of the paper. Please, take care of them and submit the further revised manuscript, with highlighted (tracked) the changes made on it.

Best regards

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1. Page 5: "In order to ensure the reliability of measurements, only dataset, of which acquisition rate higher than 50%, were used during all analysis procedures."
Please, clarify this sentence since its meaning is not clear. Probably, replace that
sentence with something like "collected, validated data spanned at least 50% of the
day". In any case, say more explicitly what has been done.

2. Page 13, line 9: "The daily mean kappa values range between 0.07 and 2.19, with a mean of 0.41 ± 0.10."
What is the utilized symbol here? Obviously, you mean k, not "kappa", right? Please use the correct symbol.

3. In any case, be careful to avoid any confusion between the fitting coefficient k (Eq. 1)
and the hygroscopicity parameter "kappa". Symbols must be clearly different to each
other. I suggest to use another symbol for the fitting coefficient, not "k", in order to
avoid confusion.

4. Add one or few sentences in the Introduction, emphasizing what is the novelty of the
present study compared to previous ones and what is the new knowledge brought to
the readers.

5. Finally, take care of improving the use of english throughout the text. If possible, let the
paper be read and corrected by a native english speaking person.

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AR by Young Jun Yoon on behalf of the Authors (24 Aug 2017) Author's response Manuscript

ED: Reconsider after minor revisions (Editor review) (10 Sep 2017) by Nikos Hatzianastassiou

AR by Young Jun Yoon on behalf of the Authors (12 Sep 2017) Author's response Manuscript

ED: Publish subject to technical corrections (26 Sep 2017) by Nikos Hatzianastassiou

AR by Young Jun Yoon on behalf of the Authors (27 Sep 2017) Author's response Manuscript

Short summary

This paper reports the long-term measurements of atmospheric aerosol physical properties at King Sejong Station, Antarctic Peninsula. It has been found that a strong seasonality of the characteristics exists in aerosol concentration and cloud condensation nuclei.