Ground-based observation of clusters and nucleation-mode particles in the Amazon

Wimmer, Daniela; Buenrostro Mazon, Stephany; Manninen, Hanna Elina; Kangasluoma, Juha; Franchin, Alessandro; Nieminen, Tuomo; Backman, John; Wang, Jian; Kuang, Chongai; Krejci, Radovan; Brito, Joel; Goncalves Morais, Fernando; Martin, Scot Turnbull; Artaxo, Paulo; Kulmala, Markku; Kerminen, Veli-Matti; Petäjä, Tuukka

doi:https://doi.org/10.5194/acp-18-13245-2018

Articles | Volume 18, issue 17

https://doi.org/10.5194/acp-18-13245-2018

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

Special issue:

Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5)...

https://doi.org/10.5194/acp-18-13245-2018

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

Articles | Volume 18, issue 17

Research article

|

14 Sep 2018

Research article |

| 14 Sep 2018

Ground-based observation of clusters and nucleation-mode particles in the Amazon

Daniela Wimmer, Stephany Buenrostro Mazon, Hanna Elina Manninen, Juha Kangasluoma, Alessandro Franchin, Tuomo Nieminen, John Backman, Jian Wang, Chongai Kuang, Radovan Krejci, Joel Brito, Fernando Goncalves Morais, Scot Turnbull Martin, Paulo Artaxo, Markku Kulmala, Veli-Matti Kerminen, and Tuukka Petäjä

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Final revised paper (published on 14 Sep 2018)
Preprint (discussion started on 24 Aug 2017)

Interactive discussion

Status: closed

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

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RC1: 'Comment on "Direct observation of molecular clusters and nucleation mode particles in the Amazon"', Anonymous Referee #1, 14 Sep 2017
- AC1: 'Author comment; Replies to Referee1', Daniela Wimmer, 13 Dec 2017
RC2: 'Review', Anonymous Referee #2, 24 Oct 2017
- AC2: 'Author comment, Replies to Referee 2', Daniela Wimmer, 13 Dec 2017

Peer-review completion

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

AR by Daniela Wimmer on behalf of the Authors (13 Dec 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (14 Dec 2017) by James Allan

RR by Anonymous Referee #1 (21 Dec 2017)

RR by Anonymous Referee #2 (11 Jan 2018)

Suggestions for revision or reasons for rejection

1) The authors defined pristine by saying “The occurrence of NPF on ground level in the Amazon region has not been observed previously in pristine conditions. In this work, pristine refers to CCN concentrations of a few hundred cm-3.” That definition is a little careless. It is quite possible to measure CCN at 0.15% supersaturation and find number concentrations of a ‘few hundred cm-3’. At that supersaturation, the particles would be about 100 nm diameter or larger, which for a number concentration of a few hundred/cc is unlikely to be a pristine situation. Also, the authors never define CCN in the manuscript. If you truly mean pristine, then you should rephrase the above sentences as follows: “The occurrence of NPF on ground level in the Amazon region has not been observed previously in pristine conditions, in which the aerosol has not been influenced by anthropogenic pollution.” If that is inappropriate, then find a word other than pristine to use.

2) There is a problem with the revised sentence on line 66. Perhaps “…event days are a factor of two lower…”

3) In response to another comment, the authors wrote the following modification: ‘T0t is influenced by pollution about once per week, where T3 on the other hand is reached once per day/once per every second day, especially in the afternoon (Martin et al., 2010b supplementary material, Thalmann et al, 2017, de Sa et al, 2017).’ Instead of ‘where T3 on the other hand is reached once…’, I assume you meant to say something like “whereas T3 is impacted about once…”

4) The authors missed my point regarding my previous comment “Lines 374-376 and figure 6 – For the ions in the 0.8-2 nm particles, it looks like they simply turn on at rain intensities above 1.” You responded “We made Figure 6 in order to show the relation between rain intensity and ion concentrations. At rain intensities below 1 mm/h the ion concentration especially in the cluster ion size range only contains the natural in background as they are produced via radon decay or galactic cosmic rays. The background cluster ion band can be observed worldwide, yet the concentrations depend on the location as it depends on the sources and sinks for the ions.” My point, which I should have made clearer, was that your statement that “some log-linear relation between the ion concentration and rain intensity could be observed for rain intensities >1 mm h-1 for all the three size bins” is incorrect for Fig 6a. In that case, the log-linear relationship for the T0t ion concentrations is not evident: their variation with rainfall appears to turn on about a rainfall intensity of about 10 mm/hr, and it does not exhibit the clear increase with increasing rainfall intensity as it does in the other five plots. Perhaps that is connected to a higher background concentration of smaller ions, but the exception needs to be mentioned. Also, please correct the legend in Figure 6 that refers to ZF2 rather than T0t.

5) Concerning my comment 18) Figure 7 and lines 385-395, you “rephrased the paragraph in the revised manuscript, line 509-518: ‘The 10-20 nm particle concentration showed first a decrease followed by a slight increase up to ~35 cm-3, peaking later than the 6-10 nm particles. However, it is unlikely that these 10- 20 nm particles originate from the same rain-induced burst as seen inside the canopy, as there is no apparent particle growth from the NAIS measurements. It is unlikely that those particles survive until the top of the canopy, as the tree leaves would filter them out. Wang et al. (2016) reported that nucleation mode particles produced in cloud outflows will be transported down with the rain, such that they can be observed at the ground level as an increase in nucleation and Aitken mode concentrations (Dp <50 nm). The appearance of 6-10 nm particles with its peak concentration, could present a similar scenario of small particles brought down from the free troposphere.’” Why is it that 6-10 nm particles going up will be filtered out by the canopy, but 6-10 nm particles going down will make it to the ground: are the downward particles carried in the wake of the rain drops, leaving less time and for diffusion to the vegetation compared with the upward particles? Please elaborate a little on the mechanisms that differentiate the upward- versus downward-moving particles.

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ED: Reconsider after major revisions (12 Jan 2018) by James Allan

AR by Daniela Wimmer on behalf of the Authors (15 Jun 2018) Author's response

ED: Referee Nomination & Report Request started (22 Jun 2018) by James Allan

RR by Anonymous Referee #1 (19 Jul 2018)

ED: Publish subject to minor revisions (review by editor) (23 Jul 2018) by James Allan

AR by Daniela Wimmer on behalf of the Authors (05 Aug 2018) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (06 Aug 2018) by James Allan

The previous comments have been addressed, however the paper is still clearly not finished yet. While most of the errors that remain could pass for 'technical', there still remains evidence for a lack of attention to detail and there are still many instances where the English could still do with improvement. Therefore, I would like to see another revision before I can deem this publishable and I've marked this down for 'minor' revisions again. The examples I've picked out below are probably not exhaustive, but the language usage in particular is still in need of much general work. After editing, I would strongly suggest that the authors get the manuscript independently checked before the next version is submitted.

* The revised statement "Previous observations in Brazil showed the occurrence of nucleation mode particles." Is lacking in context. Please revise to "Previous observations elsewhere in Brazil showed the occurrence of nucleation mode particles." or similar.
* The revised statement "The inside the rainforest (T0t) site" is not good English. Consider revising to "The site inside the rainforest".
* In the same sentence, "mostly parallel wind to Manaus" doesn't make sense. Do the authors mean that the prevailing wind was perpendicular to the direction of Manaus?
* The phrase "one of the most natural continental locations on Earth" really doesn't make any sense. Is there such a thing as an unnatural continental location?
* Section 2.1.1 goes straight onto section 2.1.3. What happened to 2.1.2?
* What do the authors mean by 'Vaisala system'? An automated weather station? The authors also describe this twice in the revised text.
* The make and model number of the ARM CPC should be given.
* The edited paragraphs in section 3.1 are very badly written in places; I will not list all the mistakes and bad grammar here but these need generally revising for English usage.
* Figure 1 still refers to an 'inside canopy' site in the figure, in spite of the caption being updated.
* The text uses '*' as part of scientific notation, whereas the table uses 'e'. To add to this, the figure captions referring to IQRs uses the alphabetic 'x' for multiplication. The standard ASCII multiplication symbol would be the most appropriate in each instance, but the authors should at least be consistent.

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AR by Daniela Wimmer on behalf of the Authors (16 Aug 2018) Author's response Manuscript

ED: Publish as is (23 Aug 2018) by James Allan

Short summary

This work focuses on understanding the production of very small airborne particles in the undisturbed environment of the Amazon basin. Computer models have shown that up to 70 % of these tiny particles are responsible for cloud formation on a global scale. The processes behind the production of these very small particles have been studied intensely recently. Their appearance has been observed almost all over the world. We directly measure sub-3 nm aerosols for the first time in the Amazon basin.