Variations of ice nuclei concentration induced by rain and snowfall within a local forested site in Japan

Release of Highly Active Ice Nucleating Biological Particles Associated with Rain

“…The second group of INPs was tested for heat sensitivity. Previous studies have suggested that biological INPs tend to be heat-sensitive [22,25,40,41], and that the freezing temperature of droplets containing atmospheric particles decreases, as the IN activity of OM becomes inactive after heating [33,34,42]. The IN activities of several microbial genera have been shown to become inactive following heat treatment to at least 105 • C [43][44][45].…”

“…Additionally, Huffman et al, detected IN-active microbes in atmospheric particles by using DNA analysis. Based on their findings, it was noted that there is possibly a positive feedback loop between biological particles and INPs, wherein biological INPs promote precipitation, which, in turn, leads to the repeated release of biological particles [29,[33][34][35]. However, the evidence in support of such theories is based on indirect findings that the INPs and biological particles in the atmosphere during rain follow similar concentration variations, despite the large difference in the number concentrations between the atmospheric INPs and biological particles.…”

Variations in airborne bacterial communities at high altitudes over the Noto Peninsula (Japan) in response to Asian dust events

“…Bioaerosols are thought to influence atmospheric processes by participating in atmospheric chemical reactions and in the formation of cloudnucleating particles (Pratt et al, 2009;Morris et al, 2011;Hara et al, 2016b). Indeed, airborne microorganisms act as ice nuclei that are related to ice-cloud formation processes (Möhler et al, 2007;Delort et al, 2010;Creamean et al, 2013;Joly et al, 2013).…”

Rainfall drives atmospheric ice-nucleating particles in the coastal climate of southern Norway

“…Hence, for the same mass, the kinetic energy of rain (proportional to the velocity squared) is at least an order of magnitude larger compared to precipitation in the form of snow, and so the energy is available for dispersion and aerosolisation of particles. Hara et al (2016) saw enhanced concentrations of INP −7 during rainfall, but not during snowfall at Kanazawa, a coastal city in Japan. Huffman et al (2013) suggested that rainfall may trigger the release of INPs from vegetation through its mechanical impact.…”

“…Therefore, icenucleating particles (INPs) active at −8 • C or at warmer temperatures (from here on collectively denominated as INP −8 ) could strongly influence precipitation development, despite their usually small number concentration in the atmosphere, for example compared to mineral dust or soot particles. The few atmospheric data on INP −8 suggest that vegetated lands are stronger sources than deserts (Conen et al, 2015), and that rainfall triggers the aerosolisation of such INPs from forest (Hara et al, 2016). Aerosolisation is probably due to the mechanical impact of raindrops on surfaces hosting organisms that, as a whole or in parts, can serve as INPs.…”