The efficiency of secondary organic aerosol particles acting as ice-nucleating particles under mixed-phase cloud conditions

Abstract

Abstract. Secondary organic aerosol (SOA) particles have been found to be efficient ice-nucleating particles under the cold conditions of (tropical) upper-tropospheric cirrus clouds. Whether they also are efficient at initiating freezing under slightly warmer conditions as found in mixedphase clouds remains undetermined. Here, we study the icenucleating ability of photochemically produced SOA particles with the combination of the Manchester Aerosol Chamber and Manchester Ice Cloud Chamber. Three SOA systems were tested resembling biogenic and anthropogenic particles as well as particles of different phase state. These are namely α-pinene, heptadecane, and 1,3,5-trimethylbenzene. After the aerosol particles were formed, they were transferred into the cloud chamber, where subsequent quasi-adiabatic cloud activation experiments were performed. Additionally, the ice-forming abilities of ammonium sulfate and kaolinite were investigated as a reference to test the experimental setup.Clouds were formed in the temperature range of −20 to −28.6 • C. Only the reference experiment using dust particles showed evidence of ice nucleation. No ice particles were observed in any other experiment. Thus, we conclude that SOA particles produced under the conditions of the reported experiments are not efficient ice-nucleating particles starting at liquid saturation under mixed-phase cloud conditions.

Characterisation of the Manchester Aerosol Chamber facility

“…the chamber and studied in detail. In addition, its unique capability of transferring the whole contents of MAC to MICC provides the grounds for aerosol-cloud interaction studies (e.g., Frey et al, 2018).…”

“…To better understand the sources, physicochemical properties and aging processes influencing atmospheric aerosols, simulation chamber facilities have been developed across the globe since the 1960s (Cocker et al, 2001b, Karl et al, 2004, Carter et al, 2005, Paulsen et al, 2005, Saathoff et al, 2009, Wang et al, 2011, Platt et al, 2013, Schnitzhofer et al, 2014, Leskinen et al, 2015, Babar et al, 2017, Gallimore et al, 2017, Leone et al, 1985. In principle, a simulation chamber is a controlled system to elucidate processes that occur in the real atmosphere (Barnes and Rudzinski, 2006), gas-phase reactions and chemical pathways (Carter and Lurmann, 1991, Seakins, 2010, Atkinson et al, 1992, SOA production (Hallquist et al, 2009, Carlton et al, 2009, McFiggans et al, 2019, new particle formation (Smith, 2016, Wang et al, 2020, Wagner et al, 2017, Dunne et al, 2016, cloud processes (Wang et al, 2011, Frey et al, 2018, Wagner et al, 2006, transformations and properties of real-world emissions (from vehicles; e.g. Liu et al (2017), biomass burning; e.g.…”

“…Additionally, the entire contents of the MAC can be transferred directly to the MICC (Manchester Ice Cloud Chamber) to investigate the warm, mixed phase and fully glaciated cloud formation on the aerosol particles that will act as cloud condensation nuclei (CCN) and ice nuclei (IN). A detailed description of the coupling between the facilities and its use can be found in Connolly et al (2012) and Frey et al (2018) and will not be discussed here.…”

Characterisation of the Manchester Aerosol Chamber facility

“…To better understand the sources, physico-chemical properties, and ageing processes influencing atmospheric aerosols, simulation chamber facilities have been developed across the globe since the 1960s (Karl et al, 2004;Cocker et al, 2001a;Carter et al, 2005;Paulsen et al, 2005;Saathoff et al, 2009;Wang et al, 2011Wang et al, , 2014Platt et al, 2013;Schnitzhofer et al, 2014;Leskinen et al, 2015;Babar et al, 2016;Gallimore et al, 2017;Leone et al, 1985). In principle, a simulation chamber is a controlled system to elucidate processes that occur in the real atmosphere (Barnes and Rudzinski, 2006), gas-phase reactions and chemical pathways (Carter and Lurmann, 1991;Seakins, 2010;Atkinson et al, 1992;Paulot et al, 2009;Surratt et al, 2010;Ehn et al, 2012;Bianchi et al, 2019, Thornton et al, 2020, secondary organic aerosol (SOA) production (Hallquist et al, 2009;Carlton et al, 2009;Mcfiggans et al, 2019), new particle formation Wang et al, 2020;Wagner et al, 2017;Dunne et al, 2016), cloud processes (Wang et al, 2011;Frey et al, 2018;Wagner et al, 2006), transformations and properties of real-world emissions (from vehicles; e.g. Liu et al, 2017, biomass burning; e.g.…”

“…Additionally, the entire contents of the MAC can be transferred directly to the MICC (Manchester Ice Cloud Chamber) to investigate the warm, mixed-phase, and fully glaciated cloud formation on the aerosol particles that will act as cloud condensation nuclei (CCN) and ice nuclei (IN). A detailed description of the coupling between the facilities and its use can be found in Connolly et al (2012) and Frey et al (2018) and is not discussed here.…”