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Zusammenfassung:
In the sixth IPCC report, the highest value of atmospheric aerosol radiative forcing was attributed to the interaction between aerosol and clouds. Four in situ campaigns focused on aerosol-cloud interactions were conducted at Mount Milešovka in the Czech Republic to gain more insight into size-dependent aerosol activation and its dependence on meteorological parameters. Low cloud episodes coded as fog, freezing fog, or rain with fog were compared to episodes without phenomena. The activated fraction (a fraction of activated particles in all available particles) was calculated from the difference of aerosols measured behind the total air inlet and the PM2.5 inlet (Zíková et al., 2020). No effect of photochemistry on activation was found; in contrast, some dependence on relative humidity, temperature, wind speed, and liquid water content (LWC) proved useful (Zíková et al., 2021). The strongest correlation was found between activation and LWC; for LWC below 0.10 g/m3, a decrease in activation with decreasing aerosol size was found. Above an LWC of 0.10 g/m3, activation did not vary much. Thus, for LWC below 0.1 g/m3, in the LWC-limited regime, LWC levels and variables affecting LWC were the main factors affecting activation, whereas for LWCs above 0.1 g/m3, in the LWC-independent regime, several parameters may have played a role. This work was supported by the CSF Grant GJ18-15065Y. Zíková, N. et al. (2020) Atmospheric Environment, 230, 117490.Zíková, N. et al. (2021) Journal of Hydrometeorology, 22(10), 2565–2579.
