Articles | Volume 21, issue 15
© Author(s) 2021. This work is distributed underthe Creative Commons Attribution 4.0 License.
Aitken mode particles as CCN in aerosol- and updraft-sensitive regimes of cloud droplet formation
- Final revised paper (published on 06 Aug 2021)
- Supplement to the final revised paper
- Preprint (discussion started on 15 Mar 2021)
- Supplement to the preprint
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor |
: Report abuse
- RC1: 'Comment on acp-2021-221', Anonymous Referee #1, 01 Apr 2021
- RC2: 'Comment on acp-2021-221', Jingyi Chen, 21 Apr 2021
- AC1: 'Response to both referee reports', Mira L. Pöhlker, 25 Jun 2021
Peer review completion
AR: Author's response | RR: Referee report | ED: Editor decision
AR by Mira L. Pöhlker on behalf of the Authors (27 Jun 2021)  Author's response Author's tracked changes Manuscript
ED: Publish as is (30 Jun 2021) by Hailong Wang
AA: Author's adjustment | EA: Editor approval
AA by Mira L. Pöhlker on behalf of the Authors (28 Jul 2021) Author's adjustment Manuscript
EA: Adjustments approved (31 Jul 2021) by Hailong Wang
This manuscript investigates the contribution of Aitken mode particles to cloud droplet formation, and the sensitivity of this contribution to the main influencing factors. The study is based on a large set of simulations made using an adiabatic cloud parcel model. While the used approach itself it by no means novel, the simulations conducted here and their interpretation clearly adds new insight into the topic of cloud droplet activation. I therefore consider this paper original enough for publication. The conducted study is scientifically sound, and there no apparent errors in methods or interpretation of results. I recommend accepting this paper for publication after the authors have addressed the few comments outlined below.
Discussion of the results of simulations is quite detailed and requires, in many places, a lot of attention from a reader. While I accept this feature in general, there is one specific place that need to be modified: Figure 3. This figure (especially panes b and c ) is way too complicated, with multiple axises and legends that are difficult to digest. I would strongly recommend simplifying this figure, or even splitting it into 2 parts. The text discussing this figure might also be worth simplification.
Mathematically, two modes in a particle number size distribution overlap each other because a log-normal mode a tail that continues for infinity. In the cases simulated in this work, the overlapping region is a notable fraction of the overall particle population, as the two modes are centered relatively close to each other. As a result, some Aitken mode particles are always larger (and thereby activate easier to cloud droplets) than some accumulation mode particles. In reality, this mathematical feature might be acceptable if the two modes represented different sources and thereby had potentially very different chemical composition. But this feature is highly questionable in aged air masses, like in cloud-processed air where all particle to the right of the Hoppel minimum should be counted as accumulation mode particle and those left to it as Aitken mode particles. The authors should bring up this issue and discuss it shortly in the paper. My main concern here is that does this upper tail of the Aitken mode (or the part of the tail that in reality should be called as accumulation mode particles) influence notably the estimated contribution of Aitken mode particles the cloud droplet population (this might be important as the criterion for notable contribution here is that 5% of cloud droplets originate from the Aitken mode, see Figure 7).
line 188: It can be concluded that…
Figure 7: The labels of the panels (a, b, c and d) are missing from this figure.