Processes contributing to cloud dissipation and  formation events on the North Slope of Alaska

Sedlar, Joseph; Igel, Adele; Telg, Hagen

doi:https://doi.org/10.5194/acp-21-4149-2021

Articles | Volume 21, issue 5

https://doi.org/10.5194/acp-21-4149-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-21-4149-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 21, issue 5

Research article

|

18 Mar 2021

Research article |

| 18 Mar 2021

Processes contributing to cloud dissipation and formation events on the North Slope of Alaska

Joseph Sedlar, Adele Igel, and Hagen Telg

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Final revised paper (published on 18 Mar 2021)
Preprint (discussion started on 17 Aug 2020)

Interactive discussion

Status: closed

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

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RC1: 'Review of “Processes contributing to Arctic cloud dissipation and formation events that bookend clear sky periods” by Sedlar et al.', Anonymous Referee #1, 31 Aug 2020
- AC1: 'Response to Reviewer 1', Joseph Sedlar, 24 Nov 2020
RC2: 'see attached document', Ian Brooks, 07 Sep 2020
- AC2: 'Response to Reviewer 2', Joseph Sedlar, 24 Nov 2020
RC3: 'Review summary', Anonymous Referee #3, 17 Sep 2020
- AC3: 'Response to Reviewer 3', Joseph Sedlar, 24 Nov 2020
RC4: ''Review of “Processes contributing to Arctic cloud dissipation and formation events that bookend clear sky periods” by Sedlar et al.', Anonymous Referee #4, 22 Sep 2020
- AC4: 'Response to Reviewer 4', Joseph Sedlar, 24 Nov 2020

Peer-review completion

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

AR by Svenja Lange on behalf of the Authors (25 Nov 2020) Author's response

ED: Referee Nomination & Report Request started (12 Dec 2020) by Timothy J. Dunkerton

RR by Anonymous Referee #1 (18 Dec 2020)

RR by Anonymous Referee #3 (03 Jan 2021)

Suggestions for revision or reasons for rejection

This is a clearly improved version of a study where the authors attempt to explore reasons for dissipation and formation of low clouds in the Arctic, using a multitude of data from the ARM site in Utqiagvik (Barrow).

The framing and organization of the study is much improved and has less of a “helpless searching” character; they go in with a hypotheses and invalidates most of them; that’s clearly useful results. I’m basically fine with the revision, I only have a few minor points below that the authors can use if they wish to clarify/improve the text more.

Line 10: Drop “relatively”; it is “limited”, full stop.

Lines 31-33: Valid only if albedo is also high enough.

Line 60: No atmosphere anywhere is very stationary; the Arctic atmosphere is no exception.

Line 76: Unclear use of “transition of cloud lifecycle”. First, a “cycle” implies “transition”, so what is a transition of the cycle? Second, does this (= low CCN count) apply also on cloud formation?

Line 142: “… attenuated in by the presence …”?

Line 140: Unclear formulation in “Near-surface measurements … where observed …” I submit you either “used” near-surface measurements or “observed” near-surface meteorological variables.

Lines 162-174: I can think of cases, especially close to a coastline, where there would be substantial but partial cloudiness for extended periods of time while the nadir-pointing instruments would either indicate completely clear or completely cloudy conditions.

Line 170: Why 96%? Why not 95% – or 90%?

Lines 198-199: Later you find little evidence that aerosols change much at either “bookend”, but for this example there seems to be a large almost “hard-top” change; a little confusing as one goes into the story with this image imprinted on the retina. Maybe this was an odd case; maybe you should drop the CPC results in this figure.

Lines 204-205: Not an English expert, but I associate “vast” with space as in a large area; here it is used with “persistence” which is temporal. Is there such a thing as a “vast persistence”?

Line 211: Pretty obvious that it would, don’t you think?

Figure 3: It looks to me that adjacent months are quite similar within seasons. Given the few cases (September & October only six) I wonder why you choose to show this monthly and not by season. Also wonder how representative some of these profiles are.

Lines 293-294: Correct me if I’m wrong, but up tpo this point the discussion is general, including both “bookends”, so the “cloud lifecycle changes” include both dissipation and formation? Then does the concentration drop across both. Also see my earlier comment about changes (or transitions) in life cycles; the cycle implies a change, so what is a change in the cycle?

Line 298: Here it seems to shift from general to specific; dissipation. Maybe mark this by a new paragraph.

Line 329: Confusing: “… are not limited to Aitken but include larger particle sizes that can activate.” Do you mean smaller?

Line 338: Using “… imply that … may not …” indicates unnecessary uncertainty. Stick to only “imply”; that is sufficient.

Line 354: I would use “a large fraction of”. With the surface being one anchor point and the other being ~500 m, while “a fraction of” could be interpreted as even only 1% of the whole, the sentence becomes confusing.

Line 367: “… clear-sky LWN and LTS modes …” sounds like these two variables had two separate modes, rather than that the combined pdf of both has different modes. Suggest using “LWN/LTS modes”.

Line 415 and onward: The wind direction by itself is a blunt instrument; one can have a small change in a generally southerly wind, say from 165 to 195 degrees, as a cold front passes moving east to west, but still with a substantial change in air mass. The latter may be much more significant than for example changes from 180 to 360 degrees on either side of a passing high-pressure ridge within the same air mass.

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RR by Anonymous Referee #4 (09 Jan 2021)

RR by Ian Brooks (15 Jan 2021)

ED: Publish subject to minor revisions (review by editor) (27 Jan 2021) by Timothy J. Dunkerton

AR by Joseph Sedlar on behalf of the Authors (28 Jan 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (15 Feb 2021) by Timothy J. Dunkerton