Dear Dr. Keerthy,
I have read the answers that you have provided to the comments of both reviewers. Based on that, I encourage you to submit a revised version of your work that takes into account the modifications mentioned in your answers.
Many thanks in advance for your efforts,

Kind regards

Marilaure Grégoire

Dear Dr. Keerthi,,
I have read the revised version of your manuscript as well as the comments of the two reviewers on this revised version and on the answers that you have provided to their criticisms. Reviewer 1 is not satisfied by your answers to his/her criticisms while reviewer 2 suggests some new improvements and does not agree with your conclusions that your work contradicts Wiggert et al (2002) findings.
Based on that I recommend major revisions of your manuscript and, in particular I would like you to tackle the following points:
In his/her first review, reviewer 1 would have liked you to address the role of dust-induced Fu input in driving the interannual variability of chlorophyll. In some part of your answers you say that it is not important for driving interannual variability while in other places you suggest that finally it may be important (2002 and 2004). In the revised version, you give arguments justifying your approach based on Aumont et al., 2008 results. I would suggest that 1) in the description of the model you justify why you impose a climatological seasonal cycle without interannual variability for dust storm (e.g. as mentioned in the title the scope of your paper is to address the physical control, and this choice was made supported by Aumont et al., 2008 findings); 2) in the discussion, I would like that you envisage to look whether the year 2002 and 2004 which do not seem to obey to the physical control have particular dust storm events in your region (I do not like the last sentence of page 13, which is vague, see my comment below); this could also be helpful that in the introduction when you enumerate the different factors that may control the interannual variability of chlorophyll in the region you mentioned that dust storm (+references) and justify why you decide to focus on the physics (reference to Aumont et al 2008).
Your answers to reviewer 1 comments concerning the differences of 2007 and 2008 can also be considered as vague, even if the relationship is indeed non-linear some explanation on why the chlorophyll does not follow the increase of nitrate can be found with your modeling tools (this is one of the aims of models). This will allow to further highlight the added value compared to past studies in terms of the understanding of mechanisms.
Reviewer 2 does not agree that conclusions of your work contradict those of Wiggert et al., 2002. There is a disagreement between the reviewer’s interpretation and yours. This is important to clarify that point since in a lot of places in the manuscript (already in the abstract) you mentioned that your findings contradict those of previous studies. In particular, I would like that you comment on the possible limitations of correlating averaged (in space and time) values of MLD, TCD and Schl, that you more thoroughly justify your estimations of TCD (and why you consider that TCD it is a good indicator of the daily variations of the MLD), comment on the capacity of the data that you have to assess TCD at this time scale.
Some other comments:
Introduction line 14, Schl needs to be defined there because you use it afterwards in Figure 1 before its definition in section 2.

Figure 6: please explain how these averaged curves have been produced for the model MLD, TCD (model results averaged at observation points? Or averaged over the whole domain?). If I am right, you are not modeling the wind (this is confusing to have it in the model as well) what about the nitracline depth? Is it from the data? If yes, again how the model average is computed? What about the heatflux (mode vs data) ?

Section 4: “The hypotheses of Wiggert et al. (2002) and Prasanna Kumar et al. (2001) for the
mechanisms that controls SChl interannual variations imply a correlation of SChl anomalies with TCD and MLD anomalies, respectively”. This is where the reviewer does not agree with you. Please make your justification clearer as why a correlation between Schl and diurnal variations of MLD implies a correlation with monthly basin averaged TCD anomalies. This is where there is a disagreement.
Figures 8 and 9: please clarify whether you average the Schl at only points (in space and time) where and when you have observations of MLD and TCD?
Page 13, line 30: “Even though the non-seasonal iron aerial deposition is not included in our model, it is able to ..”. The first part of this sentence is not clear, do you mean that the absence of consideration of an interannual cycle? Please reformulate.

Page 13, last sentence, “However, the mismatch between model and observations for a couple of winters may be related to the absence of interannual variability of iron deposition, which is not included in the model.“
I find this sentence in contradiction with what is mentioned above :” Even though the non-seasonal iron aerial deposition is not included in our model, it is able to accurately capture the observed interannual variability of the chlorophyll bloom in winter (Fig. 7a), suggesting that this mechanism is unlikely to play a dominant role in ..”. First you say that the model is very good then you say that there are mismatches. Do you mean that the model is usually good expect during some years which can be due to the absence of a consideration of the interannual (variability of iron deposition (please clarify).

Page 14, first paragraph, I do not really capture the main message that the authors want to communicate with this paragraph. Do you mean that one of the main messages of this manuscript (positive correlation between MLD and Schl) depends on model resolution? I like the idea to confront different findings but here the reader is expecting a deeper analysis (e.g. impact of model resolution on model performance and, in particular simulation of MLD, Schl, TCD, which model finding is the “best” one) of these different findings which could be the topic of another paper. Is there a publication that analyses the interannual variability of the MLD and Schl correlation in the NAS based on the global model? If not I find difficult to analyze the different findings in 15 lines, this is confusing.
Page 14, lines 27: “Wiggert et al. (2009) results also point to a contrasted biological signature of the western AS during the 1997/1998 and 2006/2007 El Niño events, with an overall decrease of productivity during the earlier and a slight increase during the latter”. This sentence seems in contradiction with the one above “Murtuggude et al. (1999) showed that SChl was anomalously high during December 1997 and January 1998, consistent … » . Please clarify. Do you mean that this is not clear what is the impact of El Nino events on the Schl?

Thank you for your efforts in answering these comments,

Kind regards,

Marilaure Grégoire

Dear Dr. Keerthi,

I have read the revised version of your manuscript "Physical control of the northern Arabian Sea winter chlorophyll interannual variations" as well as your answers to my comments and to those of the two reviewers. Based on that, I am pleased to accept your manuscript for publication in Biogeosciences.

Thank you for having submitted your manuscript to Biogeosciences.

With kind regards,

Marilaure Grégoire