General comments:

The data set, focusing on carbohydrates in arctic aerosols at different altitudes in the atmosphere and samples of relevant depths from seawater, represents a valuable contribution, which is novel in its detail. Explicitly the high data coverage including autumn to spring months and the three showcases dissecting different meteorological and stratification scenarios are interesting. The manuscript makes a comprehensive contribution to disentangling the sources and role of carbohydrates present in primary marine aerosols, provided that the results and discussion are still appropriately revised. While the methods seem robust and are clearly outlined (however, I am not an expert in sampling aerosols nor in executing meteorological or trajectory calculations), I am not convinced by certain assumptions and interpretations, which are in particular drawn from case III. I would recommend to further include comparative figures and literature to evaluate concentration ranges and composition of CCHO. Overall, the manuscript is well structured and the language is appropriate.

With regards to the conclusions drawn from case III (high CCHO, calcium and magnesium concentrations versus lower sodium concentrations, samples influenced by cloud droplets) and the correlation between oxalate and xylose as discussed in chapter 3.3, I would suggest that the authors consider the following scenario. Elevated oxalate concentrations have been identified to correspond to the biological productive seasons above remote oceanic regions (Rinaldi et al., 2011), while xylose concentrations increase after certain phytoplankton blooms (Sperling et al., 2017). Marine aggregates, such as TEP composed of carbohydrates, also increase during blooms and are further relying on divalent cations such as Ca. Oxalate on the other hand, forms complexes with divalent cations including Ca (Furukawa and Takahashi, 2011), while oxalic acid increases hygroscopicity. In case III, aerosol particles were sampled within cloud water. Cloud water has been previously shown to exhibit a high number of TEP (van Pinxteren et al., 2022). As the authors stated, lower Na concentrations could be explained by previous wet precipitation (L528), while higher Ca and Mg concentration could result from the CCHO matrices excluding Na. I am thus not sure if the suggested secondary production pathway within the atmosphere is the most obvious/reasonable potential pathway explaining the data sets presented here.  

Specific comments:

L68 The critical information here is that carbohydrates are a major product of photoautotrophic organisms, which represent the base of the food web. Carbohydrates can be rapidly consumed by heterotrophic organisms, however, in dependence of their structure and composition.   

L362 I would recommend to group winch/pier and balloon samples into the corresponding categories: a) identical, b) lower at the ground, c) higher at the balloon and represent the categorized data in a corresponding plot (e.g. boxplots). It is complicated to track every single date and sodium concentration listed back to the timeseries (Figure 2) and then compare it to the corresponding CCHO concentration (and potentially composition) in aerosol particles (L485-498). Especially, because the authors later state that sodium and CCHO concentrations covaried (L495).

L443 As the results from the seawater analysis seem to be an integral part of your results and also the discussion would profit, I would include at least one comprehensive figure on seawater composition in the main manuscript and not only supplement.

In general, it would be very interesting to see a comparative figure of the (relative) carbohydrate composition from the seawater, over the pier and winch to higher altitudes (balloon). This would also enable the authors to better judge on the state of transformation (e.g. bacterial degradation) as comparative literature exists at least for oceanic profiles and mesocosm bloom studies (e.g. Goldberg et al., 2009; Engel, Harlay et al., 2012; Sperling et al., 2017; Hasenecz et al., 2020). Potentially further information could be revealed, which may assist with the interpretation of the three case studies.

L546 Again, the relative CCHO composition is not represented and would add a valuable contribution to the manuscript (see comment above).

L697 Sodium was markedly higher at the ground.

L711 This assumption sounds a little biased, see comments provided above and below with regards to the interpretation of results.

L721 I am not sure if atmospheric aging has been proven at this point. Potentially refer to 'atmospheric processing'. Differences in aging/ the residence time would also imply differences in source locations.

L771 As the model does not resolve the SML, which is frequently enriched as also stated by the authors, not crossing the marginal-ice zone does not necessarily imply no major oceanic contributions.

L788 'aerosolized taxa' refers to bacteria, which are commonly found in oceanic or terrestrial surfaces? Clarify.

L789 Many heterotrophic bacteria metabolize carbohydrates. Especially in the surface ocean, they rely heavily on primary products, including major fractions of carbohydrates, with phytoplankton production at the base of the food chain. I.e. if it is assumed that these bacteria were transferred from the ocean surface into aerosol particles, such metabolic characteristics are ordinary.

L864-865 This is only one side of the possible interpretation: Maybe xylose was only present in the CCHO of aerosol particles and not at all processed and/or released into the free fraction?

Technical corrections:

L72-73 Rephrase sentence as incomplete.

L721 If em-dashes are used instead of comma or brackets, please use a concise size etc. Their usage is rather unusual in a scientific context, and I would recommend to reduce them throughout the whole manuscript.

L402 Balloon (III) is two times mentioned in figure 2a and varies with altitude. Please clarify and include a statement in the figures caption.

L599 'both HALFBACs' As the sentence is very long, it is not clear until L604 if the comparisons are related to the balloon (III) and zeppelin (IV) observations in figure 3a or rather to ground and altitude samples, as specified only at the end. Clarify.

Zeppenfield et al. focuses on the role of marine carbohydrates as cloud/ice condensation nuclei and their transport throughout the atmospheric column via in situ measurements. This is an interesting and detailed study and highly relevant when considering the rapidly retreating sea ice in the Arctic and how it could impact regional cloud and precipitation formation. The sampling that shows the evolution of the particles with height is especially interesting. The manuscript is well written and I have no comments on their methodology which is sound. I imagine that this will be of great interest the general ACP reader, thus I recommend publication.

Minor comment:

L47: Perhaps better to reword since some aerosol also absorb LW radiation from the earth’s surface, e.g. instead of “sunlight” to say shortwave and longwave radiation.

The Arctic continues to change due to a warmer climate. The expanding ice-free ocean areas emerge as emission sources of sea spray aerosol (SSA) particles. Zeppenfeld et al performed balloon-borne and ground-based measurements of major species in SSA particles in autumn 2021 and spring 2022 at Ny-Ålesund. They claim that the similarities or differences in SSA species between ground level and high altitude are strongly influenced by meteorological conditions and atmospheric mixing. The microbial activity might be an important source of carbohydrates in SSA particles. The language is good, but the current manuscript is descriptive and too long to read. It is easy to get lost when reading the manuscript. Major revisions are required before the manuscript can be considered for publication. Here are the comments that needs to be addressed:

Major Comments:

1. Section 3.1 is too long to read. While the authors provide great details and discussion in light of the literature, I find it very difficult to catch the take-home message. Please make it compact and concise so that it will be readable.
2. Section 3.2 is very long and descriptive. The discussion should not only analyze each of the three different cases individually but also compare them to one another. Again make it compact and concise.

Minor Comments:

1. Section 2: I appreciate the levels of detail provided for measurement. To make it reader-friendly, I would suggest including a table to summarize what parameters have been measured and used.
2. Figure 1 is a busy plot. I do appreciate the effort in data visualization. However, I feel it is hard to get the key information about Na⁺, CCHO, and CCHO/Na⁺ without looking at the legend back and forth. I would suggest having the concentrations of Na⁺, CCHO, and their ratios in bulk water, SML, and aerosol particles as the y axes and color code the height.
3. Line 394: Please elaborate more on the atmospheric ageing processes.
4. Line 435: What is the rationale behind the claim “most probable local emission source for SSA”?
5. Lines 442-443: Again what is the rationale behind the claim “the primary source of atmospheric CCHO_aer”? I guess this statement only applies to the study here.
6. Liens 743 – 746: How did the authors come up with a one to two order magnitude reduction in absolute particle masses?

Technical Comments:

1. CCNs and INPs are only used a few times. It is redundant to use the abbreviations, since they are not the focus of the work.
2. Lines 363-367: The sentence can be shortened by saying “… at both locations, winch and balloon (e.g., 30 September: 191 vs 207 ng m^-3;…)” Repeating “at the winch” and “at the balloon” is not necessary. The same applies to Lines 367-373.
3. Line 374: Just wondering if atmospheric depletion processes is the right term. Can we just use “atmospheric processes”?
4. Lines 391-392: What was consistent between studies? Na⁺ concentration?
5. Line 431: It is unclear when the colder and darker months are.
6. Figure 3: Could the authors provide the legend for solid and dashed lines for the subplots on the right-hand side?
7. Some of the abbreviations are not necessary when they are used a few times throughout, e.g., LWP, IWC.
8. Line 761: What do selective removal processes mean?
9. Figure S7: Could you include the measurement location on the plot?