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UCLALES-SALSA is a detailed high-resolution model for studying aerosol-cloud interactions in shallow clouds. The model is based on a large eddy simulator UCLALES which was coupled with a sectional aerosol-cloud microphysics module SALSA. The model was recently coupled with a Secondary Organic Aerosol (SOA) formation module. The SOA module contains lumped Volatile Organic Compound (VOC) categories such as biogenic monoterpenes and isoprene, and anthropogenic aromatics. Their oxidation produces Semi-Volatile Organic Compounds (SVOCs), which partitioning between vapor and particle phases. The partitioning is modelled using a Volatility Basis Set (VBS) approach. The module also contains aqueous-phase SOA (aqSOA) formation.The model was tested using a LES setup based on in-situ stratocumulus cloud observations from Kuopio, Finland. The observed low aerosol number concentrations and high aerosol organic factions indicated that SOA formation could have a significant impact on cloud properties. First, by allowing the partitioning of SVOCs the condensed-phase organic aerosol (SOA) concentration becomes temperature dependent. In this case the temperature decreased due to radiative cooling, which increased the SOA mass and the cloud droplet number concentration (CDNC). Surface VOC emissions are important for maintaining SOA production as the reactive VOCs are otherwise consumed rapidly. Thanks to the effective vertical mixing, surface emissions had direct impact on CDNC. Finally, the impact of aqSOA formation depends mainly on anthropogenic emissions because VOC emissions from local boreal forests are dominated by monoterpenes which are not effective aqSOA precursors., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The LAPBIAT measurement campaign took place in the SMEAR I measurement station located in Eastern Lapland in the spring of 2003 between 26 April and 11 May. In this paper we describe the measurement campaign, concentrations and fluxes of aerosol particles, air ions and trace gases, paying special attention to an aerosol particle formation event broken by a polluted air mass approaching from industrial areas of Kola Peninsula, Russia. Aerosol particle number flux measurements show strong downward fluxes during that time. Concentrations of coarse aerosol particles were high for 1–2 days before the nucleation event (i.e. 28–29 April), very low immediately before and during the observed aerosol particle formation event (30 April) and increased moderately from the moment of sudden break of the event. In general particle deposition measurements based on snow samples show the same changes. Measurements of the mobility distribution of air ions showed elevated concentrations of intermediate air ions during the particle formation event. We estimated the growth rates in the nucleation mode size range. For particles

The LAPBIAT measurement campaign took place in the Värriö SMEAR I measurement station located in Eastern Lapland in the spring of 2003 between 26 April and 11 May. In this paper we describe the measurement campaign, concentrations and fluxes of aerosol particles, air ions and trace gases, paying special attention to an aerosol particle formation event broken by a air mass change from a clean Arctic air mass with new particle formation to polluted one approaching from industrial areas of Kola Peninsula, Russia, lacking new particle formation. Aerosol particle number flux measurements show strong downward fluxes during that time. Concentrations of coarse aerosol particles were high for 1–2 days before the nucleation event (i.e. 28–29 April), very low immediately before and during the observed aerosol particle formation event (30 April) and increased moderately from the moment of sudden break of the event. In general particle deposition measurements based on snow samples show the same changes. Measurements of the mobility distribution of air ions showed elevated concentrations of intermediate air ions during the particle formation event. We estimated the growth rates in the nucleation mode size range. For particles