the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Vertical variability of aerosol properties and trace gases over a remote marine region: a case study over Bermuda
Taiwo Ajayi
Yonghoon Choi
Ewan C. Crosbie
Joshua P. DiGangi
Glenn S. Diskin
Marta A. Fenn
Richard A. Ferrare
Johnathan W. Hair
Miguel Ricardo A. Hilario
Chris A. Hostetler
Simon Kirschler
Richard H. Moore
Taylor J. Shingler
Michael A. Shook
Cassidy Soloff
Kenneth L. Thornhill
Christiane Voigt
Edward L. Winstead
Luke D. Ziemba
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- Final revised paper (published on 23 Aug 2024)
- Supplement to the final revised paper
- Preprint (discussion started on 06 May 2024)
- Supplement to the preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2024-1065', Anonymous Referee #1, 16 May 2024
Ajayi et al report observations of trace gases, aerosol properties, and meteorological variables during 15 aircraft spirals near Bermuda in June of 2022. This study provides information on the vertical distribution of these observations at a location with a history of surface-based observations. This vertical information is unique for this area and will aid interpretation of surface and satellite-based observations. The paper mainly reports the observations, describing what they observed, without much detailed analysis or interpretation. However, this is a unique and relatively large data set that may be valuable for interpretation or reinterpretation of past and future studies in the Bermuda area, as well as for understanding satellite observations of trace gases and aerosol over the oceans. The vertical information was provided by 2 separate aircraft, one flying at higher altitudes and the other flying in spirals between 0.15 to 8 km altitude. The aircraft had multiple instruments to measure meteorological parameters, aerosol properties, and trace gas concentrations. The higher-flying aircraft deployed dropsondes to measure vertical profiles of temperature, relative humidity, and wind speed.
They categorize the different vertical soundings into three source regions using the HYSPLIT model. The three regions, North America, Ocean, and North Africa/Caribbean, identified by HYSLPIT are confirmed with the observed trace gases and aerosol chemical composition. They found considerable vertical variability in all three categories, with generally higher trace gas concentrations with increasing altitude (especially for ozone). Sub-micron particle concentrations also increased with altitude suggesting new particle formation in the free troposphere. Super-micron concentrations were highest near the surface and negligible above the boundary layer. Organics tended to dominate aerosol mass in the FT while sulfate and chloride was more important closer to the surface.
This paper is suitable for publication in ACP. This data could have comprised several papers that include a more detailed analysis of the observations. The data is high quality and will be useful for such future studies and thus warrants publication. A few minor comments to improve clarity are below.
Line 224: Is it 2-3 days or 2-3 hours? I think days but I’m not sure why “hours” is there.
The short paragraph beginning on line 272 states differences in CO2 concentrations between the MBL and FT but zero analysis is given. Are these differences significant? Are they expected? Why are they different?
Section 3.6: Remind the reader the aerosol size distribution that the AMS samples at the beginning of this section. Mean numbers are given in this section. It would be good to also state the variability in some way, such as the standard deviation of the mean.
Table 6 caption: “total mass threshold > 0.4…” Threshold for what? Is this the detection limit?
Paragraph beginning on line 509: Please provide information on the variability about the mean for the Cl/Na ratio.
Citation: https://doi.org/10.5194/egusphere-2024-1065-RC1 -
RC2: 'Comment on egusphere-2024-1065', Anonymous Referee #2, 11 Jun 2024
The manuscript "Vertical variability of aerosol properties and trace gases over a remote marine region: A case study over Bermuda" presents an analysis of airborne data collected during 15 vertical spiral soundings over Bermuda as part of the NASA ACTIVATE field campaign. The study focuses on understanding the vertical distribution of trace gases and aerosol properties from different air mass source regions (North America, Ocean, Caribbean/North Africa). The data from this paper is valuable to the community, as such vertical measurements of the marine atmosphere are rare.
I do not have any major concerns about this paper. There are some minor suggestions and comments:
- Abstract: When describing the major findings, the structure of the five bullet points is inconsistent. Some are complete sentences, while others are not. I suggest using the same sentence structure throughout.
- There are many abbreviations in this paper. I suggest summarizing them in a table for clarity.
- Based on Figure 3, the wind speed at ~8000 m is only 5-10 m/s. Why is the wind speed so low? Additionally, I recommend not using red and green to distinguish different markers as they can be difficult to differentiate for colorblind readers.
- Figure 5: What is the type of aerosol diameter used in Figure 5? Is it electrical mobility diameter or aerodynamic diameter?
- Figure 8: I suggest adding a legend to the figure to explain the color representations.
- Why does the sulfate concentration decrease with increasing altitude?
- Figure 9: How do you calculate MForangic? Sea spray contains a lot of NaCl, which is refractory material to the AMS. I suggest using AMS organic mass/PM1 to get MForangic.
Citation: https://doi.org/10.5194/egusphere-2024-1065-RC2 -
AC1: 'Comment on egusphere-2024-1065', Taiwo Ajayi, 18 Jun 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-1065/egusphere-2024-1065-AC1-supplement.pdf
Peer review completion
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