|This revised manuscript reads much better than the last one - the objectives, main points and conclusions are presented more clearly. The data set is the results of the first multi-level ozone flux measurements in a deciduous forest. Although more detailed analyses are needed to carefully examine the various drivers of ozone dynamics, it is valuable to present the data set and make it available for the next-step model studies. |
Below are a couple of remaining questions:
1) The authors’ reply to the question about the possible role of BVOC in ozone deposition is reasonable, but why not include the response in the manuscript? In the Introduction, chemical reactions with biogenic volatile organic compounds is listed as one of the non-stomatal deposition processes. When trying to understand the enhanced ozone deposition flux at the canopy top during morning hours, the possible role of BVOC would always come up. It would be helpful to briefly state the results of prior investigations on it and cite the references.
2) One of the main conclusions of the manuscript is that the soil NO emission and NO from the photolysis of NO2 are responsible for the observed additional flux at 24 m compared to that at 32 m, with the former being the larger factor. Based on the ozone flux and mixing ratio data in Figures 8 and 6, it appears the ozone deposition velocity is highest at 24 m and decreases with height. This implies the reaction of the soil-emitted NO and ozone happens mainly near the canopy top, not lower and closer to the forest floor. Given the reported ozone mixing ratio, the lifetime of NO is on the order of 100 s. This is to say that the turbulent mixing within the canopy needs to be on the time scale that NO is transported to the upper part of the canopy but not ventilated to the atmosphere above. Do the data support this?
Would it be possible for one or more of the coauthors to go over the English for this manuscript and fix the remaining problems?
Page 1, line 26: is it “morning coupling between the forest and the atmosphere” or rather, the mixing within the canopy?
Page 2, line 3: “2018),” should be 2018). – change the comma to a period at the end of “)”.
Page 2, line 4-5: The deposition of O3 on forest ecosystems has been extensively studied over the last 20 years with eddy covariance field campaigns (Padro, 1996; Cieslik, 1998; Lamaud et al., 2002; Mikkelsen et al., 2004; Gerosa et al., 2005, 2009a, 2009b; Launianen et al., 2013) which were made possible thanks also to the development of fast ozone analysers, functional for such measurements.
Page 2, line 7-8: Change “while more recently campaigns had extended the observation periods and…” to “while more recently campaigns have extended observation periods and…”
Page 2, line 11-12: Change “by trees, through leaves stomata.” to “by trees through leaf stomata.”
Page 2, line 12: change “physiological factors which drive” to “physiological factors that drive”.
Also, one line below, “availability which is positively...” to “availability that is positively…”.
Page 2, line 16: change “many processes which have still to be understood in deep” to “many processes remaining to be understood in depth”.
Page 2, line 16: please add Cape, 2009 to the reference list.
Page 2, line 22: change “Actually, very few studies” to “Actually, only a few studies” to fit better with the meaning of the sentence.
Page 2, line 23: change “ forest, for example, “ to “ forest. For example, “ to break a run on sentence to separate sentences.
Also, please correct the author’s name: Launianen.
Page 2, line 24: I am not sure the statement “Dorsey et al., (2004) focused on the role of soil NO emission in the ozone flux dynamics.” is accurate. I think the role of soil NO emission is only part of the discussion in that paper.
Page 2, line 25: “There are still very few studies…” should be either “There are still few studies….”, which basically means “There are no studies…”, or “There are only a few studies….”, which means there are some, but not many/not enough number of studies.
Page 2, line 27: Change “On the contrary, measurements of vertical gradients of ozone concentration have already been quite investigated (Fontan et al. 1992; Keronen et al. 2003; Utiyama et al. 2003; Gerosa et al. 2005).” to “On the contrary, vertical gradients of ozone concentration have already been extensively investigated (Fontan et al. 1992; Keronen et al. 2003; Utiyama et al. 2003; Gerosa et al. 2005).”
Page 7, line 29: Change “which are negligible respect to those related to the other considered.” To “which are negligible with respect to those related to the other considered.”
Also, it is not clear what “the other” is referring to.
Page 8, line 5 and line 15, “per seconds” should be “per second”.
Page 8, equation (2): I don’t think SNO is correct here. With SNO, the unit of FNO would not be a unit for flux.
Page 9, line 12, 14, 20: Please fix the figure numbers.
Page 9, line 28: It would be good to specify or characterize what “quite irregular” mean here. In other words: what do you mean by “quite irregular”?
Page 11, line 23: “ozone fluxes and LE fluxes seem to be correlated”. Would it be more illustrative to plot ozone fluxes vs. LE fluxes?
Page 13, line 1: “only few studies” should be “only a few studies”.
Page 13, line 6: Please add Arya, 1989 to the reference list.
Page 31, Figure 9: Shouldn’t the units for NOx fluxes be ug N/m^2/h? If it’s per second, the reported fluxes would be too large.