Data Paper
Keiichiro Hara, Masanori Yabuki, Masataka Shiobara, Naohiko Hirasawa, and Takashi Yamanouchi. Long-term
measurements of black carbon concentrations at Syowa Station, Antarctica. Polar Data Journal. 2024, 8, p. 55–66.
https://doi.org/10.20575/00000056.
(Received 10/10/2023; Accepted 4/22/2024)

1st submission
Editor Start Date: 10/11/2023
Editor Stop Date: 11/9/2023

Reviewer #1 (10/12/2023–11/8/2023)
Reviewer #2 (10/12/2023–10/25/2023)

Editor comments to the Author: Ryu Uemura
The reviewers have raised several important points, which I ask you to consider and revise.
Both of the reviewers also have kindly pointed out the English language problems.
Please be sure to have your manuscript proofread in English by a native English speaker or a private company before
resubmitting.

Reviewer #1: Anonymous
This paper reports mass concentrations of black carbon (BC) aerosols measured by the two different types of filterbased optical instruments at Syowa Station in the Antarctic. Considering the climatic impacts of BC and its role as a
tracer for long-range transported pollutants from the mid- and low-latitudes to the Antarctic, the long-term dataset of
BC was valuable, and the contents of the paper match the scope of Polar Data Journal (PDJ). The reviewer believes themanuscript can be published in PDJ after minor revisions corresponding to the comments below.

Specific comments:
L38 and L48: "Furthermore, BC can alter the Earth's surface albedo after deposition onto snow surfaces in polar
regions." "Because of low BC concentrations in the Antarctic atmosphere, BC effects on radiation budgets are
regarded as negligible."
These two sentences seem inconsistent. Do the authors claim that the contribution of BC in the Antarctic atmosphereto the radiation budget is negligible, but the contribution of BC deposited on the Antarctic snow is not? Clarifications
are needed.
L97: "Filter spots changed every 24 hr or decrease of transmittance." The meaning of this sentence is not clear. Pleaseconsider revising the wording. Is there any threshold ATN value to change the filter spots? For the aethalometer, it
is mentioned in L162.
L101-138: This paragraph starts with explaining both instruments (aethalometer and MAAP), but the descriptions in
L118-138 seem applicable only to the aethalometer. The structure of the paragraphs should be refined.
L173-185: The definition of the data-remaining rate needs to be clarified. For example, if local contaminations occur
21 hours a day, is the daily mean value still obtained from the non-contaminated data for 3 hours? Is there any
threshold (data number or duration) for calculating mean and median values?

Technical corrections:
Please consider corrections to the wording listed below.
L87: "taken" -> "made"L95: "in" -> "for"L101: "For the measurements taken using" -> "For"
L102: "the optical absorption of optical-absorbing particles" -> "the light-absorbing particles
L107: "denoted" -> "defined"
L118: "mass BC concentrations" -> "BC mass concentrations" or "mass concentrations of BC"
L128: "determined" -> "fixed"?
L131: "values" -> "value"
L159: "compared to" -> "than"
L160: "Less" -> "The small"
L161: "higher" -> "highReviewer #2: Anonymous
GeneralThis data paper describes the results from the long-term measurements of the mass concentrations of black carbon(BC) aerosols at Syowa Station, Antarctica. The descriptions include the sampling site, the air sampling, BC data
derivations, screening the data affected by local anthropogenic activities, and the derived long-term trend of BC massconcentrations. The major outcome from this long-term measurement at Syowa station, Antarctic BC massconcentration record, is valuable and has a potential to be widely used by the research communities of the atmosphericscience. Despite the significance of this work, there are several important issues to be addressed before accepting themanuscript. Please consider the following comments and necessary revisions of the manuscript.

Major comments
1. Terminology to define light-absorbing materials in atmospheric aerosols
Petzold et al. (2013) discussed the terminology to define light-absorbing materials in atmospheric aerosols andrecommended to select their name depending on how they are measured or on their physicochemical properties. Lightabsorbing carbons from a filter photometer, which is a light absorption method with a mass absorption cross section(MAC), should be equivalent black carbon (EBC) instead of BC. If independent evaluations of the measurements suchas elemental carbon (EC) from the thermal optical method are available, the validated “EBC” can be termed simply as
BC. In this study, EBC should be used instead of BC unless otherwise validated.
2. Validity to modify the MAC value for MAAP (MACMAAP) from the manufacturer-recommended one in this study
In section 3, authors stated “The BC concentrations ~ and the MAC of 10.3 m 2 g-1”. As authors suggested, Kanaya
et al. (2013) reported, based on thorough intercomparison experiments with an independent measurement, that
MACMAAP was evaluated to be 10.3 m2 g-1 at an urban site and remote island in Japan. Please clarify why authors
applied the MAC value evaluated at two sites in the midlatitude region to the data obtained in Antarctica. Reasonable
explanations and discussion about this point are critically needed here, because authors assumed that the EBC
concentrations measured using a MAAP were more accurate than those using an Aethalometer, and scaled the
Aethalometer-derived EBC to MAAP-derived EBC with the MAC value not verified in Antarctica.
3. English proofreading by “native English speakers” is definitively needed.
There are so many sentences which are not clear and/or have grammatical errors. Please consider the proofreadingof the revised manuscript by native-Englich speakers. In many parts of the manuscript, authors used “optical”
absorption, attenuation, and transmittance. “optical” indicates the broad sense to some extent. In the research field of
the aerosol photometry, “light” has been often used instead of “optical”. To my knowledge, this will be a better
presentation to the community. In the following specific comments, I raised this point, however I might not fully pointout all of them. Please consider the use of the community-accepted terms.

Specific comments
L2. Title. Antarctic should be Antarctica? Similar confusions (noun or adjective) were found throughout the manuscript.
Please check this point in the revised manuscript.
L23. What were climate effects other than the impacts on the radiative budgets? If authors can clearly show, pleasemodify or rewrite “climate effects” by different appropriate words. If not, it should be removed.

L27–28. “to elucidate transport process and climate effects” of what? And, “the screening” of what?
L31. “Antarctic regions are” should be “Antarctic region is”.
L34. “Generally speaking,” (I think this is colloquial expression) should be “In general,” or is not needed here. (thissentence is clear without “In general”)
L38. “optical-absorbing” should be rephrased by “light-absorbing”. (The latter one is more often used)
L38–39. “deposition” should be “depositing”. To my knowledge, the BC deposition can affect the snow surface albedo
in the third pole region. Please consider to include some references to describe the darkening of the snow surface inthe third pole region.
L44. Refence #17 described the local anthropogenic sources of EC in Greenland, not Antarctica.
L44–45. This sentence includes some comparative adjectives (lower and higher), but has no word to describe “thansomething”. Please clarify this sentence.
L51. “As described herein” should be “In the following”.
L56. “For this study” is not needed here.
L57–58. This present perfect sentence should be rewritten as the past sentence.
L61. “during summer” should be “during austral summer”.
L65–66. The sentence “Therefore, the air quality ~ from the continent)” is duplicative to the previous sentence. Pleaseconsider the revision of this sentence or merge this sentence into the previous sentence.
L76. “current speed” should be “average velocity”.
L87. “through” should be “to”.
L90–92. The Aethalometer “was” operated ~ in 2008–2022. The MAAP “was” operated ~ 16.7 L min-1. “Also” should
be removed (i.e, no need).
L95–96. “respectively” should be placed at the last of the sentence.
L97. Filter spots “for the particle collection were” changed every 24 hours or decrease in transmittance. What is thethreshold value of the transmittance to change the filter spot?
L111–112. “respectively” should be placed at the last of the sentence.
L112. “optical attenuation coefficient” should be “light attenuation coefficient”.
L117–118. “respectively” should be placed at the last of the sentence. The units for the parameters should be added forclarity. “spot area” should be “particle spot area”. “optical attenuation” should be “light attenuation”. “corrected”
should be “calculated”.
L120, Eq. 3. For a precise expression, 10% and 50% should be 0.1 and 0.5, respectively.
L122–123. optical absorption coefficient > absorption coefficientmass specific optical absorption cross-section > mass absorption cross-section
mass specific attenuation cross-section > mass attenuation cross-section

L130. ”useful” should be “applicable”.
L132. “nm m2 g-1 λ-1” is not an adequate expression of the unit. Need to be corrected.
L133. “estimated” should be “calculated”.
L134. “optical attenuation and optical attenuation coefficients” should be “light attenuation”.
L135. “optical absorption” should be “light absorption”.
L136. “optical attenuation” should be “light attenuation”.
L140. “optical transmittance” should be “light transmittance”.
L141. “optical attenuation” should be “light attenuation”.
L143. “corrected already using optical scattering data” should be “already corrected using light scattering data”.
L148. “MAC for MAAP is 10.3 m2 s-1” should be “MAC for MAAP was 10.3 m2 s-1”.
L151–154. Need to describe how the detection limits for Aethalometer and MAAP were evaluated.

(Referring #19

paper is not enough.)
L160–161. “might derive” should be “might be derived”.
L187–188. “To verify the quality ~ from January 2016.” should be described in section 1, because this is closely related
to the motivation of the experiment, not to the data preparation itself.
L196. The relation can be expressed “by the least square fitting” as follows.
L198. Please add the variabilities (e.g., 95% confidence interval) to the determined coefficients of the fitting (i.e., slope
and intercept). Especially, it is important to judge whether the intercept of 0.7 ng m-3 is significantly higher than zero.
If significant, the MAAP (Aethalometer)-derived concentrations have a positive (negative) offset, which is actuallyhigher than its detection limit.
L200–201. “Here, [MAAP-BC] daily and [Aeth-BC] daily indicate the daily mean BC concentrations measured using theMAAP and Aethalometer, respectively.”
L213 and L215. The same sentence. “in” is not needed.
L220 and L222. “STD” should be “STP” (standard temperature and pressure).
L225–226. “DOY represents~” DOY is not listed in the above data field.
L237. “atmospheric observatory” is not indicated in figure 1(b) like clean air observatory.
L240. Red arrow is not indicated in figure 1(b).
Figure 2. I recommend to add a horizontal line indicating 100% in the lower panel.
Figure 3. Please add the version information to Aethalometer-derived BC concentrations. Please clarify Amb or STD.
Figure 4. I recommend to add a Y = X line. Please add the information about the regression lines shown in this figure.
Please clarify Amb or STD.

Figure 5. Please add the version information (v2) to MAAP-equivalent BC concentrations. Please clarify Amb or STD.

References for the reviewer comments
Petzold, A., Ogren, J. A., Fiebig, M., Laj, P., Li, S.-M., Baltensperger, U., Holzer-Popp, T., Kinne, S., Pappalardo, G.,
Sugimoto, N., Wehrli, C., Wiedensohler, A., and Zhang, X.-Y.: Recommendations for reporting "black carbon"
measurements, Atmos. Chem. Phys., 13, 8365–8379, https://doi.org/10.5194/acp-13-8365-2013, 2013.
Kanaya, Y., Taketani, F., Komazaki, Y., Liu, X., Kondo, Y., Sahu, L. K., Irie, H., and Takashima, H.: Comparison of
black carbon mass concentrations observed by Multi-Angle Absorption Photometer (MAAP) and Continuous SootMonitoring System (COSMOS) on Fukue Island and in Tokyo, Japan, Aerosol Sci. Technol., 47, 1–10,
https://doi.org/10.1080/02786826.2012.716551, 2013

Authors Response:
We would like to thank reviewers for taking the time to read our manuscript and providing useful feedback. We
addressed the manuscript based on reviewer’s comments. The revised manuscript was checked by native English
speaker (FASTEK, https://www.fastekjapan.com/). We believe that the manuscript would fully address reviewer’s
concern. The corrected parts were highlighted in the manuscript.

Response to reviewer #1;
Reviewer’s comment
L38 and L48: "Furthermore, BC can alter the Earth's surface albedo after deposition onto snow surfaces in polar
regions." "Because of low BC concentrations in the Antarctic atmosphere, BC effects on radiation budgets are
regarded as negligible."
These two sentences seem inconsistent. Do the authors claim that the contribution of BC in the Antarctic atmosphereto the radiation budget is negligible, but the contribution of BC deposited on the Antarctic snow is not? Clarifications
are needed.
Reply from Authors
It is certain that BC can alter albedo of snow surface, when significant amounts of BC are deposited onto to snow
surface. However, it is obvious that less amounts of BC on surface snow alter negligibly the albedo. Although we
considered that the statements were not inconsistence, terms of “in polar regions” were removed from the revisedmanuscript to avoid misunderstanding.
L97: "Filter spots changed every 24 hr or decrease of transmittance." The meaning of this sentence is not clear. Pleaseconsider revising the wording. Is there any threshold ATN value to change the filter spots? For the aethalometer, it
is mentioned in L162.
Specific values to change the filter spots were added in the revised manuscript, as follows.

Filter spots changed every 24 hr or transmittance decreased to 80%. In most cases, the filter spots changed every 24
hr because of low BC concentrations at Syowa Station.
L101-138: This paragraph starts with explaining both instruments (aethalometer and MAAP), but the descriptions in
L118-138 seem applicable only to the aethalometer. The structure of the paragraphs should be refined.
In the paragraph of Line 105, description changed to general explanation of filter-based BC measurements. Also,
Reviewer #2 suggested that the description was added. As a results, data correction of aethalometer and MAAP was
explained in the following paragraphs.
L173-185: The definition of the data-remaining rate needs to be clarified. For example, if local contaminations occur
21 hours a day, is the daily mean value still obtained from the non-contaminated data for 3 hours? Is there any
threshold (data number or duration) for calculating mean and median values?
The data remaining rate means fraction of the number of the remained BC data after screening to the total number ofthe observed BC data. This explanation was added into the text (Line 191-193).
L87: "taken" -> "made"L95: "in" -> "for"L101: "For the measurements taken using" -> "For"
L102: "the optical absorption of optical-absorbing particles" -> "the light-absorbing particles
L107: "denoted" -> "defined"
L118: "mass BC concentrations" -> "BC mass concentrations" or "mass concentrations of BC"
L128: "determined" -> "fixed"?
L131: "values" -> "value"
L159: "compared to" -> "than"
L160: "Less" -> "The small"
L161: "higher" -> "highThese issues were corrected in the revised manuscript.

Response to reviewer #2;
Reviewer‘s comment
1. Terminology to define light-absorbing materials in atmospheric aerosols
Petzold et al. (2013) discussed the terminology to define light-absorbing materials in atmospheric aerosols andrecommended to select their name depending on how they are measured or on their physicochemical properties. Lightabsorbing carbons from a filter photometer, which is a light absorption method with a mass absorption cross section(MAC), should be equivalent black carbon (EBC) instead of BC. If independent evaluations of the measurements suchas elemental carbon (EC) from the thermal optical method are available, the validated “EBC” can be termed simply as
BC. In this study, EBC should be used instead of BC unless otherwise validated.
Reply from Authors
As pointed by Reviewer, the term of “equivalent black carbon (EBC)” was commonly used in recent papers. Therefore,
we add the following sentence in Line 111-112.
As recommended by Petzold et al. (2013)30, the corrected BC concentrations mean “equivalent BC” concentrations.
2. Validity to modify the MAC value for MAAP (MACMAAP) from the manufacturer-recommended one in this study
In section 3, authors stated “The BC concentrations ~ and the MAC of 10.3 m 2 g-1”. As authors suggested, Kanaya
et al. (2013) reported, based on thorough intercomparison experiments with an independent measurement, that
MACMAAP was evaluated to be 10.3 m2 g-1 at an urban site and remote island in Japan. Please clarify why authors
applied the MAC value evaluated at two sites in the midlatitude region to the data obtained in Antarctica. Reasonable
explanations and discussion about this point are critically needed here, because authors assumed that the EBC
concentrations measured using a MAAP were more accurate than those using an Aethalometer, and scaled the
Aethalometer-derived EBC to MAAP-derived EBC with the MAC value not verified in Antarctica.
As shown in Hara et al. (2019), BC at Syowa station was supplied by long-rage transport from biomass burning andanthropogenic processes mainly in south America and Southern Africa. MAC in the Antarctic has never been toevaluated, to my knowledge. We need to use the value of MAC evaluated at the location with influence of biomassburning and anthropogenic processes. Therefore, we used the value of MAC reported by Kanaya et al. (2013) who
evaluated carefully MAC values in rural and urban cites. We added the explanation into the text (Line 156-162).
3. English proofreading by “native English speakers” is definitively needed.
There are so many sentences which are not clear and/or have grammatical errors. Please consider the proofreadingof the revised manuscript by native-Englich speakers. In many parts of the manuscript, authors used “optical”
absorption, attenuation, and transmittance. “optical” indicates the broad sense to some extent. In the research field of
the aerosol photometry, “light” has been often used instead of “optical”. To my knowledge, this will be a better
presentation to the community. In the following specific comments, I raised this point, however I might not fully pointout all of them. Please consider the use of the community-accepted terms.
The revised manuscript was checked again by native English speaker (FASTEK: https://www.fastekjapan.com/). Termof “optical” changed to “light” in the text.
L2. Title. Antarctic should be Antarctica? Similar confusions (noun or adjective) were found throughout the manuscript.
Please check this point in the revised manuscript.
The terms of “the Antarctic” and Antarctica” were checked and corrected in the revised manuscript.
L23. What were climate effects other than the impacts on the radiative budgets? If authors can clearly show, pleasemodify or rewrite “climate effects” by different appropriate words. If not, it should be removed.

The description in Line 23 was modified as follows.
…which is related closely to climate effects in polar regions.
L27–28. “to elucidate transport process and climate effects” of what? And, “the screening” of what?
The description in Line 27-29 was modified as follows.
…to elucidate transport processes of atmospheric substances to the Antarctic and to assess climate effects. Daily mean
BC data after the screening of locally contaminated data are provided herein.
L31. “Antarctic regions are” should be “Antarctic region is”.
Corrected.
L34. “Generally speaking,” (I think this is colloquial expression) should be “In general,” or is not needed here. (thissentence is clear without “In general”)
Corrected.
L38. “optical-absorbing” should be rephrased by “light-absorbing”. (The latter one is more often used)
Corrected.
L38–39. “deposition” should be “depositing”. To my knowledge, the BC deposition can affect the snow surface albedo
in the third pole region. Please consider to include some references to describe the darkening of the snow surface inthe third pole region.
Here, we focused on BC in the Antarctic region. Therefore, we did not add the explanation and references about BC in
the third polar region, although snow surface can be darkened in the third polar region by BC deposition.
L44. Refence #17 described the local anthropogenic sources of EC in Greenland, not Antarctica.
The description in Line 44-45 was modified as follows.
… although local contamination from these sources can engender temporarily high BC concentrations in polar
regions15–17.
L44–45. This sentence includes some comparative adjectives (lower and higher), but has no word to describe “thansomething”. Please clarify this sentence.
The description in Line 45-46 was modified as follows.
Indeed, earlier work has shown lower BC concentrations in the Antarctic than in other regions15, 18, 19…
L51. “As described herein” should be “In the following”.
The description in Line 53 was modified as follows.
In the following report of our work, …
L56. “For this study” is not needed here.
Modified as follows.
At the clean air observatory at Syowa Station, Antarctica (69.005°S, 39.591°E, 20 m), BC measurements were made.
L57–58. This present perfect sentence should be rewritten as the past sentence.

The sentence was not modified because Syowa station is still operated.
L61. “during summer” should be “during austral summer”.
It is obvious that our data was taken in the Antarctic area (i.e., south hemisphere). Additionally, specific month wasshown in the text. As a result, we did not modify the description.
L65–66. The sentence “Therefore, the air quality ~ from the continent)” is duplicative to the previous sentence. Pleaseconsider the revision of this sentence or merge this sentence into the previous sentence.
The description in Line 65-67 was modified as follows.
Similarly to other Antarctic stations23, katabatic winds (i.e. outflow from the continent) blow from the prevailing winddirection (NNE – ENE) at Syowa Station through the year.
L76. “current speed” should be “average velocity”.
We measured only speed in the tube. Thus, the description was not modified.
L87. “through” should be “to”.
Corrected.
L90–92. The Aethalometer “was” operated ~ in 2008–2022. The MAAP “was” operated ~ 16.7 L min-1. “Also” should
be removed (i.e, no need).
Term of “operate” is intransitive verb. Thus, not modified.
L95–96. “respectively” should be placed at the last of the sentence.
L111–112. “respectively” should be placed at the last of the sentence.
L117–118. “respectively” should be placed at the last of the sentence.
Reviewer #2 seems to believe that “respectively” has to be placed at the end of sentence. Although the usage was often
found, “respectively” can be placed in a sentence. The usage was checked by native English speakers.
L97. Filter spots “for the particle collection were” changed every 24 hours or decrease in transmittance. What is thethreshold value of the transmittance to change the filter spot?
Threshold values were added in the text (Line100-102).
L112. “optical attenuation coefficient” should be “light attenuation coefficient”.
L117–118. “optical attenuation” should be “light attenuation”. “corrected” should be “calculated”.
L134. “optical attenuation and optical attenuation coefficients” should be “light attenuation”.
L135. “optical absorption” should be “light absorption”.
L136. “optical attenuation” should be “light attenuation”.
L140. “optical transmittance” should be “light transmittance”.
L141. “optical attenuation” should be “light attenuation”.
L143. “corrected already using optical scattering data” should be “already corrected using light scattering data”.
Corrected.

L117–118. The units for the parameters should be added for clarity. “spot area” should be “particle spot area”.
Corrected to “aerosol spot area” in Line126. Unit of area was already shown in specific values in Line 103. Thus, unit
was not added in Line 126.
L120, Eq. 3. For a precise expression, 10% and 50% should be 0.1 and 0.5, respectively.
The description already explain that the values of 10 and 50 % were specific values of ATN. Additionally, earlier works
by Weingartner et al. (2003) and Collaud Coen et al. (2010) showed similar equation. To avoid confusion of readers,
we did not modify the equation.
L122–123. optical absorption coefficient > absorption coefficientmass specific optical absorption cross-section > mass absorption cross-section
mass specific attenuation cross-section > mass attenuation cross-section
Corrected.
L130. ”useful” should be “applicable”.
Corrected.
L132. “nm m2 g-1 λ-1” is not an adequate expression of the unit. Need to be corrected.
The unit is correct. The description was in accordance with manual of the aethalometer. However, we modify thesentence to avoid confusion of readers as follows.
The value of λσATN is 14625 nm m2 g-1 λ-1, as recommended by the manufacturer.
L133. “estimated” should be “calculated”.
Corrected.
L148. “MAC for MAAP is 10.3 m2 s-1” should be “MAC for MAAP was 10.3 m2 s-1”.
Corrected.
L151–154. Need to describe how the detection limits for Aethalometer and MAAP were evaluated.
(Referring #19 paper is not enough.)
Detection limit of aethalometer was discussed in Hara et al. (2019). Because detection limit of MAAP was checked bysimilar procedure, short explanation was added in the text (Line 168-169), as follows.
From similar experiments by Hara et al. (2019)19, the detection limit for MAAP-BC was approximately 0.1 ng m−3.
L160–161. “might derive” should be “might be derived”.
Corrected.
L187–188. “To verify the quality ~ from January 2016.” should be described in section 1, because this is closely related
to the motivation of the experiment, not to the data preparation itself.
The sentence was moved to Line 87-89.
L196. The relation can be expressed “by the least square fitting” as follows.
Corrected.

L198. Please add the variabilities (e.g., 95% confidence interval) to the determined coefficients of the fitting (i.e., slope
and intercept). Especially, it is important to judge whether the intercept of 0.7 ng m-3 is significantly higher thanzero. If significant, the MAAP (Aethalometer)-derived concentrations have a positive (negative) offset, which isactually higher than its detection limit.
We add short explanation on the positive intercept as follows.
Although a positive intercept was found using equation (5), positive bias in MAAP-BC relative to Aeth-BC was notclear because of the large 95% prediction bands (data population).
L200–201. “Here, [MAAP-BC] daily and [Aeth-BC] daily indicate the daily mean BC concentrations measured using theMAAP and Aethalometer, respectively.”
As reply shown above, this sentence was not modified.
L213 and L215. The same sentence. “in” is not needed.
Corrected.
L220 and L222. “STD” should be “STP” (standard temperature and pressure).
Corrected in the test and data.
L225–226. “DOY represents~” DOY is not listed in the above data field.
Corrected (removed).
L237. “atmospheric observatory” is not indicated in figure 1(b) like clean air observatory.
L240. Red arrow is not indicated in figure 1(b).
Corrected (removed).
Figure 2. I recommend to add a horizontal line indicating 100% in the lower panel.
Added.
Figure 3. Please add the version information to Aethalometer-derived BC concentrations.
Please clarify Amb or STD.
The ambient concentrations were shown in Fig. 3. Short explanation was added in figure caption.
Figure 4. I recommend to add a Y = X line. Please add the information about the regression lines shown in this figure.
Please clarify Amb or STD.
Added. Short explanation was added in figure caption.
Figure 5. Please add the version information (v2) to MAAP-equivalent BC concentrations.
Please clarify Amb or STD.
Version information was added in caption. The ambient concentrations were shown in Fig. 5.
Short explanation was added in figure caption.

2nd submission
Editor Start Date: 2/20/2024
Editor Stop Date: 4/22/2024

Reviewer #1 (2/27/2024–3/26/2024)
Reviewer #2 (2/26/2024–4/19/2024)

Editor comments to the Author: Ryu Uemura
Please correct the chapter numbers so that they do not skip. Competing interest should be 5, and figures should be 6.

Reviewer #1: Anonymous
Since most of the points raised by the reviewer have been appropriately revised, this manuscript should be accepted for
publication. Please consider the following minor corrections to the English wording.
L38: "optical-absorbing" -> "light-absorbing"
L89: "during January 2007 to January 2008" -> "from January 2007 to January 2008"
L90: "optical scattering" -> "light scattering"
L99: "Filter spots changed every 24 hr or transmittance decreased to =<80%." -> "Filter spots changed every 24 hr orwhen the transmittance decreased to =<80%."

Corrected according to the above comments.

Editorial Office’s note
Calculate checksum date: 4/23/2024
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