In this manuscript, the reaction rate constants of ∆3-carene with OH and O3, OH yield in ozonolysis, and organic nitrate yield in photooxidation were first studied by combining model simulation and laboratory investigation. Caronaldehyde, as one of the main products of ∆3-carene oxidation, its yield from OH-initiated oxidation and photolysis, and the yield of organic nitrate were further calculated. The data obtained in the present study were compared with the corresponding values in the literature and nearly all the determined values are in good agreement with the reported values. Overall, the method is mostly reasonable and the uncertainty has been well considered. However, my main concern is what is the motivation of the focus on ∆3-carene? Just considering its atmospheric abundance? As demonstrated by the authors, the reaction mechanism of α-pinene has been investigated in many studies and, ∆3-carene behaves similarly like α-pinene regarding its oxidation mechanism. In the fact, the rate constants of the reaction of ∆3-carene with OH and O3, the OH yield, as well as the organic nitrate yield have been already reported in the literature. A better introduction of the research background and motivation of learning the reaction rate constants and OH yield, as well as the significance of these studies are suggested. Overall though, this study could be published on Atmospheric Chemistry and Physics once the following comments are addressed.

Specific comments,

1. Page 4, line 85, what is the value of the detection limit of the instruments, e.g PTR-MS for the detection of ∆3-carene?
2. Page 5, line 90, 30%, how the RH in Table 1 obtained? Is 30% the averaged RH measured at the beginning and at the end of the experiment? This is suggested to be noted in Table 1 by footnote.
3. Page 6, line 121, ‘aproton’, ‘a proton’?
4. Page 7, line 165, line 165-167, why the fraction of RO2 radicals produced by ∆3-carene to the total RO2 concentration could be assumed to be equal to the ratio of OH-reactivity from the ∆3-carene + OH reaction to the total measured OH reactivity? As shown in equation 2, OH can react with NO2 but without RO2 generation. And if this assumption is right, why is kOHVOC but not kOH,obs used in Equation 4?
5. Page 12, figure 2, which curve represents the time evolution of CO? The legend should be added.
6. If the chamber was flushed with synthetic air until the concentrations of trace gases were below the detection limit of the instruments (Page 4), how this can be achieved for experiments E3 and E4? Figure 1 showed no time interval for such an operation.
7. Page 15, references for the ozonolysis mechanism is suggested to be cited.
8. Figure 4, What do the solid line and the dashed line represent? For OH oxidation, why there are different corrected caronaldehyde concentrations at one reacted ∆3-carene concentration?
9. Page 18, Figure 5, where is 35% derived from? The top ‘HO2’ in this figure should be NO2.
10. Page 21, When 249, while the calculation of RO2_,carene is reconsidered, the nitrate yield ΦRONO2 needs to be checked.

The manuscript describes results from chamber experiments to study the atmospheric fate of an important biogenic VOC, namely D-3-carene and one of its oxidation products, 3-caronaldehyde. The methods described appear to be robust, the results well supported by the data and the manuscript is commendably well-written and concise. My main concerns are around the presentation and descriptions (captions and legends) of some of the plots. I strongly recommend publication in ACP once these fairly minor issues are resolved.  

Fig 2 is missing legend information (what does the black line in the lower plot represent?) and potentially a dataset if we were really meant to see both O3 and CO time profiles.

On Fig 3, whilst a good match of experimental data to a yield of 0.65 is clear, the sensitivity of the system to this parameter is less clear. Could additional dashed lines be used to indicate yields of, for example 0.25, 0.45, 0.85 to illustrate just how sensitive was the experiment?

Fig 4 needs an improved caption. If I am interpreting it correctly, it need to state clearly that this plot was used to determine caronaldehyde yields from both (R1) and (R2).

I am a little confused by what is meant by “RO2” in Fig 5. Does this refer to the peroxyl radical derived from carene + OH + O2? If so, would the yields of both caronaldehyde and HO2 really be unity from the RO2 + RO2 channel? Could these yields be between 1 and 2? If “RO2” is meant to represent other peroxyl radicals present in the chamber then the caption does not make sense when referring to additional pathways.

One further point for clarification is regarding the rate coefficient determination for OH + D-3-carene, of k = (8.0 +/- 0.5) cm³ s^-1. I understand that a complex model was used to fit to experimentally determined decays of D-3-carene and presumably to time profiles of other species. The resulting value is reported as the mean from several runs, each reporting an “optimised value”. Do the uncertainties quoted (the +/- 0.5) account for simply variability from one run to another (i.e. 0.5 is the standard error of the mean), or is there some extra uncertainty resulting from the optimisation process?  

Minor points:

• Starting with abstract but also throughout - there should be space characters between units “cm3s-1” -> “cm3 s-1”. Else it is easy to confuse units like m s-1 (metres per second) with ms-1 (permillisecond)
• Very minor point, but where % values are used there should be no space character, so “5 %” -> “5%” as % is part of the number itself, not a unit.
• There looks to me like a typo in the fourth Atkinson reference in the bibliography “O-x”