I decide to send the revised version to referee 1 following her/his wish and therefore, I have to choose the option "Reconsider after major revisions".

Please, consider the additional major remarks by reviewer 1:
My major criticism is the apparent lack of a clear detection of the expected spectral signature of Trichodesmium slicks, which show a strong red edge, as described in section 3.3. A strong red edge is shown in Gower et al., 2014, Figure 6 derived from MERIS, and this should also appear in MODIS data. Spectra in Figure 4 show little sign of a red edge.
The paper needs work. English is poor. There are several typos.
Line 27 of page 7 mentions the need to distinguish Sargassum in this area. How realistic is this? Has Sargassum ever been observed there in quantities large enough to cause confusion?
A possible daily cycle in Trichodesmium observability is mentioned on page 9. This could be important and needs more discussion. How big a variation has been observed? How consistently?
The MCI time sequence in Gower et al., 2014 shows monthly composite images over this area for the period 2002 to 2012 (Figure2 in that paper). Do any of the high signals shown there correspond to in-situ data considered here?
Line 5. The new algorithm discussed in section 3.5 uses negative Rrs(678) to measure a red-edge signal. Using the absolute value of Rs(678) will result in errors if Rs(678) is ever positive. The negative value alone should be used.
Minor points:
Page 1.
Line 1 “is the major dinitrogen-fixing organisms.” Should be “organism.” Do we need the “di”? Are there “mono-nitrogen” fixers?
Line 15, “fails to detect sub-surface booms.” This should be “blooms.” But why criticise the algorithm for not being able to do something which must be fundamentally impossible? There can be no signal from (deeper) sub-surface blooms.
Page 3
Lines 11,12, “blooming period (Nov to Mar) coincides with the South Pacific Convergence Zone.” A period has to coincide with another period, or Zone with another Zone. I’m not sure what point you are making here.
Line 32, “three datasets intersecting.” Maybe you mean “three datasets providing data in the acquisition period”
Page 4
Lines 17,18 “SOB database and the OUTPACE campaign are used. So REMMOA is not used? Why not? You discuss it above and call it “most favorable for satellite data validation” (line 6).
Page 10
Lines 15, 16. Where in Figure 7 is the area you discuss?
Page 11
Line 5. “Two adjacent wavelengths 645 and 748.” The two adjacent wavelengths are 665 and 748. Why use 645 in Equation 4?
What is the criterion in equation 4? Must this expression be positive? Or must it be greater than some threshold value?
Line 15,16 Which “former one”?
Page 12
Line 6. What is sub-mesoscale? By one convention mesoscale is about 300km, but you must mean a much smaller value than this.
Page 13
Line 21. “citetMcKinna2011” should be “cited McKinna (2011)”
Page 14
Line 7 “floating algae organized in a heap” is a strange description. Perhaps you mean “floating algae in mats of varying surface concentration”?
Figure 2
Panels B and C captions are interchanged
Figure 4
Why are points not plotted at 748 and 870nm in panels A, C and E?
Figure 5
The geographic area needs to be better described. I assume this is the Great Barrier Reef, with land at bottom left and cloud in grey? It would be useful to outline the area of the reef itself.
Figure 6
The grey areas appear to be clouds. This needs to be made clear.
Figure 7
The Figure needs better description. Presumably, A is the top panel, B the bottom one? What are the units of the two color bars? At present the left color bar is referred to as fixation rate, the central bar is undefined. Text describing the colored dots in the lower panel is ambiguous: they are said to be blue for absence, red for presence, but the last sentence says they are only colored for presence.
Figure 8
“Only a few pixels are remaining.” “Only a few pixels remain” is better English. In fact, I would say that a significant number remain, or “The main feature is well-detected at the lower resolution.”