The investigations about the climate-relevant trace gases, such as DMS and isoprene, during the winter season of the Southern Ocean are still insufficient. Current knowledge about the distributions and sea-to-air fluxes of DMS and isoprene during the winter season of the Southern Ocean is also limited. In the modelling studies, the concentrations and fluxes of trace gases in the winter season of the Southern Ocean were usually considered to be very low. However, it is difficult to achieve field observation data to support this conclusion. The manuscript entitled "Winter season Southern Ocean distributions of climate-relevant trace gases" mainly introduced the dimethyl sulfide (DMS and related sulfur compounds) and isoprene surface water data obtained from the Atlantic sector of the Southern Ocean during the winter season (August 2019). The distributions and fluxes of trace gases during the winter season of the Southern Ocean were analyzed. Undoubtedly, the findings in this manuscript provided valuable information for the modelling studies and improved our understanding of trace gases in the polar regions. Thus, I believe that this manuscript is worth being published in the Journal of Biogeoscience after a minor revision. My comments and suggestions are attached as follows.

Minor comments:

1. On page 2, line 65, ‘400-600 Tg C yr-1; (Arneth et al…’, Delete‚ ‘(’.
2. On page 2, line 66, ‘plays an important role in the chemistry there…’, it is recommended to revise 'there' to ‘locally’.
3. On page 3, line 71, it is recommended to delete ‘subsequently’.
4. On page 5, for Figure 1(right), the cruise track is not clear. Please revise it.
5. On page 10, I suggest combining Figure 3(d) and (e).
6. The descriptions of isoprene are much shorter than those related to DMS in the manuscript. However, the data of surface water isoprene during the winter season of the Southern Ocean was possibly reported for the first time. It looks like the isoprene is not important.
7. I am curious about the amount of trace gas emission during the winter season of the Southern Ocean. Is it possible to estimate it. And how?
8. During the winter season of the Southern Ocean, the oxidation of trace gases is known to be slow under the dark and cold atmosphere. It means that the particle formation from the trace gases is not that easy. Could the authors comment on the role of trace gases in influencing the climate during the winter season of the Southern Ocean? 

This manuscript by Zhou et al. entitled “Winter season Southern Ocean distributions of climate-relevant trace gases” describes measured concentrations of dimethylsulphide (DMS, and related sulphur compounds) and isoprene in the Atlantic sector of the Southern Ocean during the winter. This is the first time the distribution of isoprene has been observed in winter.  Based on these and previous publications in the journal, this paper is appropriate for Biogeosciences. However, there are still some minor points that need to be illustrated. Therefore, the publication of this manuscript is supported if the authors can properly address my comments.

Specific comments:

1. The abstract should focus on the research results of this paper rather than its significance.
2. Page 1, line 30-32, ‘Here we focus on two typical marine biogenic gases, i.e. dimethylsulphide (DMS) and isoprene…’ The article discusses not only marine biogenic gases but also related sulphur compounds, I suggest to add a sentence of the relevant sulfides here.
3. Page 2, line 53, At the end of this paragraph, the article has been discussing the change data of radiation, and it is recommended to add a concluding sentence.
4. Page 2, line 55, ‘accounting for 50% of all BVOCs coming from terrestrial ecosystems.’ Is the information unclear here? Is it 50% of the species or the quantity?
5. Page 2, line 58, ‘Most isoprene in the atmosphere is produced by terrestrial ecosystems…’ How much is the most here? It is recommended to add data. If not, please delete ‘most’.
6. Page 2, line 61, Add a transition sentence between the source and flux sentences.
7. Page 3, line 74-75, ‘Therefore, trace gas fluxes are computed using measured wind speed, measured atmospheric concentrations, and measured seawater concentrations.’ It is repeated with the method below, it is recommended to delete it here.
8. Page 12, line 314, ‘…over the cruise track area are lower than the climatological concentrations,’ How much percent lower is Lana’s concentration?
9. In general, headings should not be followed directly by figures and tables.
10. What does DOY stand for? Shouldn't it be DAY?