This paper analyzes the sulfur cycle in the marine atmosphere using measurements from the NASA ATom mission and simulations from the AeroCom models. The study compares sulfur species measurements (DMS, SO2, MSA, and SO4) between observations and model simulations, discusses the discrepancies and the possible causes, and analyses the sources and transport of these sulfur species in the atmosphere. The results showed the dominance of anthropogenic emissions in atmospheric sulfate, especially in the upper levels of the atmosphere, and the importance of ocean emissions to the local areas near the surface. By analyzing the discrepancies between model and observation, as well as between models, the authors emphasize the need for further investigation into emissions and the chemical/dynamical processes to improve the model performance.

 

The paper maintains a coherent structure and meticulously examines extensive data sets from multiple dimensions. The ocean not only covers most of the Earth but also acts as an important source of sulfur.  By analyzing and comparing observations and simulations, the authors point out potential directions that modelers should be working towards to improve the module performance on the sulfur cycle. However, the substantial volume of data presented is overwhelming, potentially obfuscating the main points for the readers. Thus, my principal suggestion is to simplify certain sections of the paper. Also, instead of summarizing the paper, the authors should address the implications of their new findings in the conclusion section.

 

I recommend minor revisions before accepting the paper.

                         

 

It would be helpful if the authors could state the reasons for focusing on sulfur species in a more straightforward way in the introduction section. While the introduction highlights the environmental impacts of sulfur species, other pollutants not discussed in this paper also affect the environment. Why should we focus on sulfur species? Is the bias of aerosol climate models predominantly due to sulfur?

 

I would appreciate it if the authors could highlight the novelty of their work. Has any other research analyzed the ATOM data specifically for sulfur species? Is this the first study that utilizes ATOM measurements in comparison with AeroCom models? If there have been studies on sulfur variability and sources over the ocean, what novel findings does this paper present?  The authors should make some comparison with other studies in a new section or talk about it in an existing section of the paper.

 

Furthermore, if we improve sulfur simulation, what advantages can we expect? It would be helpful if the authors could briefly discuss the implications of the new findings in the conclusion section.

 

 

Some parts of the paper contain overwhelming information that may be simplified or moved to supplements. For instance, Section 3.1 allocates 28 lines (L212-L239) to discuss three different sampling intervals, which may not be key information the readers need to know. This information (corresponding to Fig 2 (a)(d)(g)(i)) only builds up one-third content in Figure 2, which makes the main point of Figure 2 very hard to catch. 

 

Another example starts from L317 where the authors spent time explaining how the flag ‘-888’ is replaced by ‘0’ to represent the low values, which, although crucial for validating results, may not be necessary for most readers.

 

Additionally, the division of 5 models into 3 groups from L340-L354 seems superfluous and is never referenced throughout the paper. I would recommend a description without grouping the models.

 

Due to the huge load of information that is shown, optimizing the layout of figures is crucial to enhance readability. For example, I would recommend relocating the legends in Figures 5-8 and putting this information on the top/bottom or right side of the charts. 

 

Since you ‘use 10-s merged data where observations above DL throughout the main text unless otherwise stated’ (L241), could you just show the results of 10-s data only on Figure 2 and move the other to the supplement?

 

Additionally, as Atom-1/2/3/4 are not following the order of the four seasons, I recommend adding notes on the seasons at a proper place in Figures 9,10,11, and 13 to guide the readers when reading through the section about seasonal changes in the paper.

 

The conclusion section is mostly a summary of the content. As mentioned earlier, the implication of the new findings can be stated in this section. 

 

 

1. Please standardize the color and font of the indices of panels in Figure 2.

 

2. Please refine Figure 12 to maintain the consistent style of other figures. 

 

3. In the caption of Figure 9, AMS should be orange instead of ‘red’. 

 

4. Please replace the vertical bar in Figure 13 with a straight line as the shape and color is misleading. 

 

5. In L467, please add a period after ‘4’.