Review of “Submesoscale horizontal stirring enhances seasonal enrichment of low-chlorophyll surface waters in the Eastern Mediterranean” 

The authors present the role of lateral exchanges by sub-mesoscale instabilities in controlling the productivity of the interior of the Eastern Mediterranean Sea. In contrast to previous studies, which have typically focussed on the vertical velocities, the authors focus on horizontal transports between the productive coastal and Nile outflow influenced regions and the oligotrophic interior. Overall, I found the paper convincing and worthy of publication in Ocean Science however I have a few suggestions below to improve the paper. 

I found the structure of the manuscript inconsistent with Ocean Science style papers and made it (at times) not very smooth to read. I regularly found myself jumping from parts of section 2 to section 4 and appendix A in order to understand the model and data sets used. I would suggest restructuring so that the methods and content in appendix A come before the results. I would also suggest strengthening the methods with more discussion of the model, the inputs (river and topography seems like they would be very important for this but are not described in the paper) and its validation to provide confidence in the results. 

I was a little confused around line 96 –97. If I understood this line correctly the model has a bio-geo-chemical component (e.g. the authors mention modelled nutrient gradients) but we are not shown any BGC results from the model. It would seem very important to see if the model used in the later analysis reproduces the satellite derived seasonal variability. 

Fig 6 and the associated text is not really demonstrated in this work. If the point is to be made it should be tested in the paper. Would it be possible using the particle tracking experiment. Can you demonstrate that the particles are accumulating on fronts prior to leaving the boundary region? Then becoming more evenly distributed once further off shore? 

Minor Comments 

Line 10 to 11 > I don’t think that the statement about  24% of the winter enhancement being driven by sub-mesoscale motions is supported by the manuscript. The only reference I could find is that the eastern box has 24% higher chl than the western box in winter. It seems a bit of a jump to then state that this is (1) all driven by submesoscale flows and (2) imply it applies to the whole region. 

Line 145 > Missing the “2)”