Influence of the Accuracy of Chlorophyll-Retrieval Algorithms on the Estimation of Solar Radiation Absorbed in the Barents Sea

Round 1

Reviewer 1 Report

Inherent optical properties of optically active constituents are critical for estimating the absorption of solar radiation. Chlorophyll a concentration, which could be retrieved from ocean color satellite data, is generally used to parametrize the presence of phytoplankton when calculating heating in the visible range. This manuscript studied the influence of chla-retrieval algorithm accuracy for the estimation. However, it’s hard for readers to judge the result because the whole process is quite complex and is related with many other components. As it shown in the conclusion part, the 30-50% accuracy of bio-optical algorithms have little effect on the vertical distribution of solar energy absorbed in the seawater. But this result could be mainly resulted from other factors, such as the deviations of the vertical distribution, or the departures of CDOM absorption, or the particle scattering coefficients.  Step-to-step validation or comparison of the hydro-optical model with in situ measured data are strongly expected. 

Some points should be considered for revision.

1.     If the chlorophyll-a concentration data were collected during daytime with the flow-through fluorimeter, the calibration process should be explained carefully by considering the non-photochemical quenching of fluorescence. (Refer to Roesler et al., 2013, Methods in Oceanography and many others)

2.     Is possible to compare the absorption and attenuation coefficient measured in situ with that estimated from the hydro-optical model? I think this point is a critical step.

3.     The R2 data in Table 2 are same for standard and regional algorithm, respectively. However, other indexes are different. Are they coincidences?

4.     There is only one sample (Figure 9) for comparing the Rrs spectra obtained from satellite with that from the model. This is not strong enough to support the main object of this manuscript. 

 

Author Response

Thanks for your careful reading and valuable comments. All comments were taken into account in the revised text of the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript presents a practical application of using radiation measurements to improve estimates made from satellite radiometry, applied to an Arctic area such as the Barents Sea where complex conditions occur in the aquatic environment.

The work is interesting to be published in the journal, especially as it is a practical application.

Some improvable details that have been observed in the manuscript are proposed.

In the introduction it would be interesting to indicate the usefulness of chlorophyll measurement at the study site. This aspect has been dealt with in other recent works as well, in which the effect of fluvial inputs that modify the state of this Arctic zone has been commented. The authors could incorporate a text explaining the interest of these measurements and of better adjusting the existing equations.

Figure 1 should include a general map of the location of the study area that would allow to globally locate the area in northern Europe for readers from other continents. Note that the deformity of the geographic projection is adequate to correctly visualize the location. An area of 1.5 degrees latitude and 8 degrees longitude is presented as if it were a square territory.

The methodology is well described and justified. It is only proposed that the standard method used for chlorophyll measurement be indicated, since the reference used is unusual.

Figure 2 could indicate the location of the measurement points located in Figure 1 with a symbol so that the reader can see where they are actually located on the map.

In the statistical variables obtained, it would be interesting to put the level of significance where appropriate. The expert in statistics already understands at a glance that it must be significant, but it is not superfluous to put the level.

The discussion is acceptable, although it lacks a discursive part in which the concordances and discrepancies of the authors' results with other similar scientific works are shown. However, as this is a case study, this detail is less important and the authors may or may not incorporate it at their discretion.

Finally, in subsequent editing, the style of the reference list should be adjusted to that used by the journal.

Author Response

Thanks for your careful reading and valuable comments. All comments were taken into account in the revised text of the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I can see the improvement of the revised version.  I think it could be accepted as a research paper.