10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Probing the Identity of the Ice Nucleating Particles (INPs) in a Boreal Environment
MIKHAIL PARAMONOV, Saskia Drossaart van Dusseldorp, Zamin Abdulali Kanji, ETH Zürich
Abstract Number: 1226 Working Group: Unraveling the Many Facets of Ice Nucleating Particles and Their Interactions with Clouds
Abstract Ice nucleation is an important pathway for cloud formation and initiation of precipitation in the atmosphere, thus affecting the Earth’s hydrological cycle, energy and radiative balance (Mülmenstädt et al., 2015). It has been shown that a significant fraction of precipitating clouds in various environments contains ice, e.g. both in the tropics (Lau and Wu, 2003) and in the Nordic countries (Sporre et al., 2014). However, in many cases, the exact identity of an ice nucleating particle (INP) in a particular environment, as well as the properties that make an atmospheric INP an efficient one are still not fully understood (Kanji et al., 2017).
A ubiquitous aerosol particle species, the effect of which on atmospheric ice nucleation has not been thoroughly investigated, is the secondary organic aerosol (SOA). Boreal forest, which covers approximately 8% of the world’s land area, is a significant source of SOA in the atmosphere. Therefore, an intensive measurement campaign, HyIce2018, is planned at the SMEAR II (Station for Measuring Ecosystem-Atmosphere Relations) boreal site in Hyytiälä Forestry Field Station in southern Finland (Hari and Kulmala, 2005). The measurement campaign is an international collaborative effort, involving several research institutions and various ice nucleation measurement techniques, supplemented by aircraft and tethered balloon, as well as the comprehensive network of aerosol- and meteorology-related continuous measurements deployed at the site. ETH Zürich will participate in the campaign in February-March of 2018 for approximately six weeks. Continuous ice nucleation measurements will be conducted by the Portable Ice Nucleation Chamber (PINC) at a temperature of 242K in condensation freezing mode (i.e. above water saturation). The expectedly low INP concentrations at the site will be enhanced by a powerful aerosol particle concentrator, which can increase the particle number concentration by as much as a factor of 25. Besides INP number concentrations measured by PINC, the chemical composition of INP will be deduced from mass spectrometry, as well as from measurements of biomass burning and biological fluorescent particles. The participation of several research groups will also allow for an intercomparison of the deployed ice nucleation measurement techniques. HyIce2018 is expected to be the first measurement campaign aiming at quantifying and qualifying the ambient INPs in a boreal environment. The planned measurement activities are expected to shed light on the identity of the INPs and the effect of SOA, biomass burning and biogenic aerosol particles on atmospheric ice nucleation.
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