Fig. 6: Effect of warm intrusion on cloud condensation nuclei.

Time series of CCN number concentrations at different supersaturation (SS) during (A) background period and (B) warm intrusion period (10 min averages). C Violin distribution plots of hourly averaged CCN number concentration for the whole MOSAiC year data (in lila) and warm intrusion data (in pink—excluding precipitation periods). D Violin distribution plots of hourly averaged particle number concentration from a CPC with a lower cutoff of >2.5 nm for the whole MOSAiC year (in lila) and warm intrusion data (in pink—excluding precipitation periods). Violin plots are a combination of boxplot and a kernel distribution function on each side of the boxplots. The white circles define the median of the distribution and the edges on the inner grey boxes refer to the 25th and 75th percentiles. Both CCN and particle concentration data are cleaned from ship exhaust emissions via applying the pollution mask (see Methods section; subsection measurement of total particle concentration). CCN data include Nov. 1, 2019 to May 9, 2020 and CPC data include Nov. 1, 2019 to Sep. 30, 2020.