The authors have reasonably responded to the reviewer comments, in particular the inclusion of the comparison against FLUXNET GPP improved the paper. This is acknowledged by both reviewers to which I have sent the revised paper for a second review given they had indicated earlier that they would like to see the revised paper.

After having giving the paper a read myself I largely agree with the reviewers in that another round of minor revisions will be necessary before the paper can become acceptable for BG. In addition to the reviewer comments I detected quite some additional issues that need to be taken care of before the paper can become acceptable for publication.

I thus ask the authors thus to consider the reviewer and my comments below and upload a correspondingly revised version together with a point-by-point reply to ALL comments and the corresponding changes.

Overall the English of the paper is quite poor at times – this however will be taken care of during copy-editing once the paper has been accepted. Many of the figures in my view are in the need of careful editing to make them more appealing, e.g. distance between axis text and axis numbering, number of ticks per axis, overlapping ticks in case of multiple axis, legend text overlapping with figure elements, consistent use of units and headers, size of panel numbering, … –it is the authors responsibility to produce figures which meet the journal’s standards and I ask the authors to consider this when submitting a revised version.

Details
p. 2, l. 3: “with the advent of”
p. 2, l. 6: remove the last part of the sentence „..., the downward flux ...“
p. 3, l. 2: remove “natural”
p. 4, l. 14: “sun-induced plant fluorescence”
p. 6, l. 21: before explaining what you do, please explicitly state the objectives and hypothesis (if any) of the study
p. 8, l. 18: this is wrong- you may use any leaf angle distribution describing it by the parameters LIDFa and LIDFb – presumably you have chosen these parameters to result in a spherical distribution!
p. 9, l. 23: what does Kn represent – explain
p. 11, l. 2: summation is somewhat misleading as the TOC fluorescence depends on the within-canopy radiative transport of radiation in the fluorescence wavebands
p. 12, l. 19: isn’t the LAI implicit in i) in l. 16 ?
p. 13, l. 6: “residual differences” – this sounds like a misnomer – you mean small/negligible differences?
p. 14, l. 21-22: sparse and dense are not necessarily good attributes for the different LAIs you simulate as sparse usually means heterogeneous horizontal structure and dense actually refers to the volume (with a LAI=4 a canopy 1m tall canopy is denser compared to a 10m tall canopy) – I suggest to remove this sentence as it is quite obvious why you chose different LAIs
p. 14, l.22-24: what do you mean with temperature and vapour pressure at leaf level? Is it the (surface) temperature of the leaf and the (saturated) vapour pressure in the intercellular space of the leaf or the air surrounding the leaf? If the vapour pressure refers to the leaf intercellular space, then there is no need to specify this as this is a function of leaf temperature (assuming saturated conditions) – please clarify this sentence in a manner accessible to ecophysiologists – one of the reviewers was also commenting on this.
p. 14, l. 25-p. 15, l. 1: this repeats what you write above
p. 15, l. 9: “to the chlorophyll AB content”
p. 16, l. 21-22: where do you then get leaf temperatures from – Bethy?
p. 17, l. 16: replace “when the electron rate is active” with “when photosynthesis is limited by electron transport” as electron transport is always active when there is light
Fig. 2, panels e and f: what does the x-axis show – radiation in the visible range (400-700nm)? Based on the values I rather have the feeling the plot is showing short-wave radiation, i.e. ca. 400-2500nm – please confirm and if so change figure and text accordingly
p. 26, l. 19: Fig 8c instead of Fig. 9c
p. 27, l. 24: “Discussion”
p. 30, l. 11; aPAR of 1400 W/m2 is likely impossible – either this is not PAR (rather global radiation) or the units are wrong (e.g. umol/(m2s) instead of W/m2); the conversion of PAR between photon and energy units is 4.5 – so for an incoming PAR of 2000 umol/(m2s) / 4.5 = 444 W/m2 in terms of incident PAR in energy units – aPAR will be correspondingly lower
p. 30, l. 20: the original version of SCOPE does calculate aPAR based on LAI and incident PAR and so forth– it is not an input to SCOPE
Supplementary material: Numbering of figures and tables should start with 1 and include the “S”, i.e. Fig. S11 should be Fig. S1

I thank the authors for appropriately dealing with my and the reviewer comments - I thus accept the paper for publication in BG.