the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 12 May 2026
Frequent occurrence of newly formed aerosol particles over wide geographical areas in the Arctic free troposphere and atmospheric boundary layer
Abstract. New particle formation (NPF) can impact the Arctic radiative energy budget since this region is particularly sensitive to changes in aerosol particle and cloud condensation nuclei concentrations. Prior studies have predominantly investigated NPF in the Arctic atmospheric boundary layer (ABL), concluding that this phenomenon primarily takes place close to the surface. However, this study shows that NPF may take place throughout the entire lower Arctic troposphere. We have reached this conclusion by analyzing particle number size distribution data collected during a springtime aircraft campaign in the vicinity of Svalbard, the Fram Strait, and northern Greenland. We detected newly formed aerosol particles at various altitudes ranging from about 60 m to 3900 m and identified three atmospheric scenarios for their occurrence: newly formed particles in the free troposphere, in the ABL over sea ice, and in the vicinity of clouds. Our results suggest that regional Arctic atmospheric processes as well as long-range transport play key roles in the formation of new particles. Based on our data, we furthermore conclude that NPF may be a frequent and geographically extended phenomenon in the Arctic free troposphere.
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Status: open (until 23 Jun 2026)
- CC1: 'Comment on egusphere-2026-2215', Farahnaz Khosrawi, 29 May 2026 reply
Data sets
Master tracks in different resolutions during POLAR 6 campaign P6-247_BACSAM2_2024 Z. Jurányi et al. https://doi.org/10.1594/PANGAEA.971763
Five-day backwards trajectories at one minute resolution along the flight tracks of the Polar 6 research aircraft during BACSAM II B. Kirbus and M. Wendisch https://doi.org/10.1594/PANGAEA.971694
Airborne in-situ measurements of aerosol particle number size distributions during the BACSAM II campaign in April 2024 D. J. Simon et al. https://doi.pangaea.de/10.1594/PANGAEA.993546
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- 1
I would like to raise the attention of the authors to the following study which I published a while ago on new particle formation in the Arctic free troposphere:
Khosrawi, F., Ström, J., Minikin, A., and Krejci, R.: Particle formation in the Arctic free troposphere during the ASTAR 2004 campaign: a case study on the influence of vertical motion on the binary homogeneous nucleation of H2SO4/H2O, Atmos. Chem. Phys., 10, 1105–1120, https://doi.org/10.5194/acp-10-1105-2010, 2010.
It would be worth mentioning this study in the introduction on e.g. P2, L50 and/or the paragraph below. Our study analysed measurements from the ASTAR 2004 campaign and frequent newly formed particles in the free troposphere up to 4000 m were there also reported.
On P6, L135 and/or 157: The Khosrawi et al. (2010) study may be mentioned here as well.
P9, L197: Here, it would be definitely worth to mention here the Khosrawi et al. (2010) study where we investigated a case where newly formed particles were observed at 7000 m.
Additional comments I have on your manuscript:
P3, L84: The distinction of NPF and newly formed particles is here a bit weird since reading the sentence it feels like the same. You later explain the difference and then it becomes clear. My suggestion would be to move this sentence after explaining the difference between NPF and newly formed particles.
P14, L314: Is descent here really correct? If precursors were emitted from the surface, I would expect that these are then transported upwards, thus that you observe an ascent of air masses.
P14, L316-318: Isn' that a bit too speculative? Are there any measurements or other studies that could support this hypothesis?
P18, 382: Add "free" so that it reads "Arctic free troposphere"?
P20, L405: I am not convinced of this statement. Why do you think that NPF could be a geographically widespread phenomen? How do you see that in your data/analysis? Aren't you focusing on a certain part of the Arctic (a certain distance around the flights that are only a minor part of the entire Arctic). However, why shouldn't NPF occur everywhere in the Arctic? There are so many possibilities to form new particles so that I would assume that NPF can occur nearly everywhere in the Arctic. Further, how you show the connection to warm air intrusions would be worth to be discussed/repeated here a bit more.
P20, L400ff: Are there already any studies or measurements that investigate the trends or changes in NPF due to climate change?