|1) The authors defined pristine by saying “The occurrence of NPF on ground level in the Amazon region has not been observed previously in pristine conditions. In this work, pristine refers to CCN concentrations of a few hundred cm-3.” That definition is a little careless. It is quite possible to measure CCN at 0.15% supersaturation and find number concentrations of a ‘few hundred cm-3’. At that supersaturation, the particles would be about 100 nm diameter or larger, which for a number concentration of a few hundred/cc is unlikely to be a pristine situation. Also, the authors never define CCN in the manuscript. If you truly mean pristine, then you should rephrase the above sentences as follows: “The occurrence of NPF on ground level in the Amazon region has not been observed previously in pristine conditions, in which the aerosol has not been influenced by anthropogenic pollution.” If that is inappropriate, then find a word other than pristine to use.|
2) There is a problem with the revised sentence on line 66. Perhaps “…event days are a factor of two lower…”
3) In response to another comment, the authors wrote the following modification: ‘T0t is influenced by pollution about once per week, where T3 on the other hand is reached once per day/once per every second day, especially in the afternoon (Martin et al., 2010b supplementary material, Thalmann et al, 2017, de Sa et al, 2017).’ Instead of ‘where T3 on the other hand is reached once…’, I assume you meant to say something like “whereas T3 is impacted about once…”
4) The authors missed my point regarding my previous comment “Lines 374-376 and figure 6 – For the ions in the 0.8-2 nm particles, it looks like they simply turn on at rain intensities above 1.” You responded “We made Figure 6 in order to show the relation between rain intensity and ion concentrations. At rain intensities below 1 mm/h the ion concentration especially in the cluster ion size range only contains the natural in background as they are produced via radon decay or galactic cosmic rays. The background cluster ion band can be observed worldwide, yet the concentrations depend on the location as it depends on the sources and sinks for the ions.” My point, which I should have made clearer, was that your statement that “some log-linear relation between the ion concentration and rain intensity could be observed for rain intensities >1 mm h-1 for all the three size bins” is incorrect for Fig 6a. In that case, the log-linear relationship for the T0t ion concentrations is not evident: their variation with rainfall appears to turn on about a rainfall intensity of about 10 mm/hr, and it does not exhibit the clear increase with increasing rainfall intensity as it does in the other five plots. Perhaps that is connected to a higher background concentration of smaller ions, but the exception needs to be mentioned. Also, please correct the legend in Figure 6 that refers to ZF2 rather than T0t.
5) Concerning my comment 18) Figure 7 and lines 385-395, you “rephrased the paragraph in the revised manuscript, line 509-518: ‘The 10-20 nm particle concentration showed first a decrease followed by a slight increase up to ~35 cm-3, peaking later than the 6-10 nm particles. However, it is unlikely that these 10- 20 nm particles originate from the same rain-induced burst as seen inside the canopy, as there is no apparent particle growth from the NAIS measurements. It is unlikely that those particles survive until the top of the canopy, as the tree leaves would filter them out. Wang et al. (2016) reported that nucleation mode particles produced in cloud outflows will be transported down with the rain, such that they can be observed at the ground level as an increase in nucleation and Aitken mode concentrations (Dp <50 nm). The appearance of 6-10 nm particles with its peak concentration, could present a similar scenario of small particles brought down from the free troposphere.’” Why is it that 6-10 nm particles going up will be filtered out by the canopy, but 6-10 nm particles going down will make it to the ground: are the downward particles carried in the wake of the rain drops, leaving less time and for diffusion to the vegetation compared with the upward particles? Please elaborate a little on the mechanisms that differentiate the upward- versus downward-moving particles.