Dear authors,

Apologies for the delay in dealing with this paper. In going through the revised papers with some care, I have identified a number of small corrections / additions I feel are necessary before the paper can be published in ACP. In addition, I have spotted a large number of types / technical errors that need to be corrected.

I am confident that you will be able to address these quite easily.
With best regards,
Eiko Nemitz


Scientific Comments:

Line 23: This needs rephrasing as the methodology is not as generalised as the authors suggest as admitted in their response to Referee #2.

Line 107/108: I do not understand this sentence. Do you mean you calculated footprints rather than trajectories?

Table 1. Please clarify in the caption to this table over which time frame these data were averaged and on what time resolution. For example, is the temperature provided the inter-day median of mean diurnal temperatures? Or were temperatures only averaged over a fraction of the day? Were interquartile ranges calculated between days or on the basis of the original raw (hourly?) data? This affects the results.

Table 2. Please clarify in the caption whether the criteria were combined, by a logical OR or a logical AND.

Summary and conclusions. Please elaborate on the final sentence, which was also requested by Referee #2. This work cites a great number of papers that have contributed to establishing the conditions under which NPF at Hyytiala is likely. This indicates the amount of work involved. Also, in my opinion it is much more likely to develop the required relationships for remote sites where air masses are homogeneous over large periods of time. It is likely to be much more difficult to find robust relationships in much more heterogeneous landscapes with cities, intensive agriculture and industry, where a small change in wind direction might bring very different air masses to the site. For these sites the understanding of what causes NPF is much less developed.


Technical Comments:

Line 40: Should read “fixed point measurements”
Line 52: Better: “have been used extensively to characterise …”
Line 61: Better: “campaign-based”
Line 67: Better: “long-term time series”
Line 71: “were likely to occur”
Line 74: Better: “was always provided”
Line 83: “… from the TNO-MACC data set”
Line 84: “… on wild fires … “ and also “wind-blown”
Line 88: Better: “For the purpose of …”
Line 89: “… during the next three days …”
Line 98: “were forecast”
Line 107: “within 100-300 km or better.”
Line 137: Correct subscripts for SO2 and PM10
Line 150: “The particulate mass concentration is available from the SILAM forecast.”
Line 164: “from the SILAM forecasts.”
Line 209: “from the east”
Line 216: “from the west or the south.”
Line 222: “On the other hand this period included quite a few days (13 out of …”
Line 226: “leading to the observation of newly formed”
Line 227: “Days on which the maximum value of the nucleation parameter NP2 exceeded 0.02 started to be more likely an NPF event day rather than a non-event day.”
Line 246: “NPF events lasting for several hours”
Line 247: “forecast to be” (also lines 248, 254, 261, 269, table 4)
Line 252: “except for two days”
Line 257: “score indices”
Line 266: “such forecasts”
Line 275. “datasets available to characterise the conditions favourable for the occurrence of particle formation.”
Table 4; Header of last column should read “Non-NPF”