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As part of the A-LIFE (Absorbing aerosol layers in a changing climate: aging, LIFEtime and dynamics) campaign, ground-based measurements were carried out in Paphos, Cyprus, to characterize the abundance, properties, and sources of aerosol particles in general and cloud condensation nuclei (CCN) and ice-nucleating particles (INP) in particular. New particle formation (NPF) events with subsequent growth of the particles into the CCN size range were observed. Aitken mode particles featured kappa values of 0.21 to 0.29, indicating the presence of organic materials. Accumulation mode particles featured a higher hygroscopicity parameter, with a median kappa value of 0.57, suggesting the presence of sulfate and maybe sea salt particles mixed with organic carbon. A clear downward trend of kappa with increasing supersaturation and decreasing d(crit) was found. Super-micron particles originated mainly from sea-spray aerosol (SSA) and partly from mineral dust.

INP concentrations (N-INP) were measured in the temperature range from -6.5 to -26.5 degrees C, using two freezing array-type instruments. N-INP at a particular temperature span around 1 order of magnitude below -20 degrees C and about 2 orders of magnitude at warmer temperatures (T > -18 degrees C). Few samples showed elevated concentrations at temperatures > -15 degrees C, which suggests a significant contribution of biological particles to the INP population, which possibly could originate from Cyprus. Both measured temperature spectra and N-INP probability density functions (PDFs) indicate that the observed INP (ice active in the temperature range between -15 and -20 degrees C) mainly originate from long-range transport. There was no correlation between N-INP and particle number concentration in the size range > 500 nm (N (> 500 )(nm)). Parameterizations based on N (>)(500)( )(nm) were found to overestimate N-INP by about 1 to 2 orders of magnitude. There was also no correlation between N-INP and particle surface area concentration. The ice active surface site density (n(s)) for the polluted aerosol encountered in the eastern Mediterranean in this study is about 1 to 3 orders of magnitude lower than the n(s) found for dust aerosol particles in previous studies. This suggests that observed N-INP PDFs such as those derived here could be a better choice for modeling N-INP if the aerosol particle composition is unknown or uncertain.