Please see attached.

Summary

This paper evaluates 1-, 3-, and 7-parameter ocean bio-optical models using the Multi-Angular Polarimetric Ocean coLor (MAPOL) joint retrieval algorithm applied to data from the Research Scanning Polarimeter (RSP) in different types of water (clear and open water and turbid coastal water). The authors compare MAPOL retrievals to MODIS products.

The topic of this paper is interesting and the approach of this paper seems sound. However, it is unclear where the novelty lies in this paper. No new algorithms are developed, and the conclusion that the 3- and 7-parameter models are more versatile than the 1-parameter model is fairly intuitive. Furthermore, there are deviations between the MAPOL retrievals and MODIS retrievals which are not fully explained. Thus, I recommend acceptance with major revisions. I suggest that the authors further analyze the differences between MAPOL retrievals and MODIS retrievals, and that the authors revise the paper to clarify the major novel contributions of this paper to the reader.

In general, I agree with the comments posted by Anonymous Referee #1 as RC1.

Comments

• Figure 4: At a wavelength of 470 nm, it seems like the MAPOL retrievals significantly underestimate AOD when compared to MODIS. Generally, MODIS retrievals are outside of the error bars for MAPOL retrievals. The authors note this (in lines 310-311) but do not explain it -- what are the potential causes?  This also appears to be an issue at 550 nm and 670 nm, but at these wavelengths, MODIS retrievals are at least generally within 1-sigma error bars for MAPOL retrievals.
• Figure 5: It might improve clarity to include a line on the plot showing where the coast actually is, or make the x-axis the distance from coast rather than longitude. At first glance, it can be difficult to understand where the coast is.
• Figure 6: I recommend including the full figure caption (and see above comment about deviations from MODIS).
• Figure 9: At 410 nm, spectral remote sensing reflectance from MODIS is consistently lower than from MAPOL (and is sometimes negative). Why is this?
• Figure 9: Please include the full figure caption.
• General note on figures: I recommend including the full figure caption for all figures.
• Lines 123-124: I recommend further explanation of POLYAC and this paper’s relevance to POLYAC. Perhaps POLYAC performance improvements can be used to motivate this paper (if it can be shown that novel contributions in this paper improve MAPOL retrievals).
• Lines 316-322: Why does MODIS estimate higher spectral remote sensing reflectance than MAPOL for pixels other than the ones closest to the coast?
• Line 327: The authors note that the uncertainty for AOD is less than 0.01 at all wavelengths -- but is the uncertainty adequately capturing error/differences from MODIS retrievals (especially noting the differences between MODIS and MAPOL)?