Understanding how aerosol particles interact with atmospheric water is critical to understanding their impact on climate and precipitations. Ice Nuclei Particles (INP) trigger the formation of atmospheric ice crystals at temperatures ranging from -5 °C up to -30 °C. They are challenging to characterize because of their scarceness in the atmosphere and their variability, especially at temperatures warmer than -20 °C. At these temperatures, the aerosol particles of biological origin can contribute significantly to INP number concentration. This study incorporates a series of offline, long-term, size-segregated measurements of INPs, collected at the Puy de Dôme station (PUY, 1465 m a.s.l.). PUY is an ideal place to study INPs concentrations as it is advected by a variety of air masses, with about 20% of them originating in the free troposphere.
We measured concentrations of INPs between -5 and -18 °C, with concentrations of 0.001 INP/L_air at the warmest temperatures, and between 0.01 and 0.1 INP/L_air at the coldest temperatures. We observe that the majority of INP measured at temperatures warmer than -15 °C are heat labile, in line with other studies. We observe a higher contribution of heat labile INPs during the winter and lower ratios in spring. The INP variability was statistically compared with collocated aerosol characterization at the site. INPs were mainly linked to local and marine tracers. We propose a new parameterization using the total number of aerosols. This parameterization is optimized for warmer temperature INPs. The parameterization showed good performance when tested on independent data sets