A072-03
New-particle formation in the free upper troposphere by nitric acid and ammonia
Wednesday, 9 December 2020: 10:38
Virtual
Mingyi Wang1, Guillaume Marie2, Birte Rörup3, Ananth Ranjithkumar4, Sebastian Ehrhart5, Theodoros Christoudias6, Daniel Schlesinger7, Xucheng He8, Lubna Dada9, Rima Baalbaki3, Ruby Marten10, Mao Xiao11, Houssni Lamkaddam10, Joschka Pfeifer12, Hanna E. Manninen12, Victoria Hofbauer13, Brandon Lopez13, Lee Mauldin14, Ilona Riipinen7, Ken S Carslaw4, Douglas R Worsnop15, Joachim Curtius2, Andreas Kurten2, Jasper Kirkby16, Imad El-Haddad17, Johannes Lelieveld18, Neil McPherson Donahue1, Hamish Gordon19 and CLOUD consortium, (1)Carnegie Mellon University, Center for Atmospheric Particle Studies, Pittsburgh, PA, United States, (2)Goethe University Frankfurt, Institute for Atmospheric and Environmental Sciences, Frankfurt am Main, Germany, (3)Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland, (4)University of Leeds, Leeds, United Kingdom, (5)Max Planck Institute for Chemistry, Atmospheric Chemistry Department, Mainz, Germany, (6)Cyprus Institute, Nicosia, Cyprus, (7)Department of Applied Environmental Science, University of Stockholm, Stockholm, Sweden, (8)University of Helsinki, Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, Helsinki, Finland, (9)University of Helsinki, Helsinki, 00014, Finland, (10)Paul Scherrer Institute, Villingen, Switzerland, (11)Paul Scherrer Institute, 5232 Villigen, Switzerland, (12)CERN, the European Organization for Nuclear Research, Geneve, Switzerland, (13)Carnegie Mellon University, Center for Atmospheric Particle Studies, Pittsburgh, United States, (14)Pacific Northwest National Laboratory, Richland, WA, United States, (15)Aerodyne Research Inc., Billerica, MA, United States, (16)Goethe-University of Frankfurt, Institute for Atmospheric and Environmental Sciences, Frankfurt am Main, Germany, (17)Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, Villigen, Switzerland, (18)Max Planck Institute for Chemistry, Mainz, Germany, (19)CERN European Organization for Nuclear Research, Physics, Geneva, Switzerland
Abstract:
New-particle formation (NPF) accounts for around half of the global cloud condensation nuclei (CCN), thus affecting earth’s climate directly and indirectly. Recently, abundant 3–7-nm particles have been observed in the tropical convective region as a global-scale band, directly linked to CCN production in the lower troposphere. Further, larger (60–1,000 nm) particles consisting largely of ammonium nitrate, along with more than 1 ppbv of ammonia, have been observed by satellite in the upper troposphere during the Asian monsoon anticyclone. Although these particles are probably formed via nucleation, the mechanism is not yet known. Here we show, through experiments performed in the CLOUD chamber at CERN, that below about -15 degrees Celsius, nitric acid and ammonia can nucleate directly through an acid–base stabilization mechanism to form ammonium nitrate particles, which can grow rapidly by ammonium nitrate condensation. This mechanism may provide an important source of new particles in the relatively clean and cold upper free troposphere, where ammonia can be convected from the continental boundary layer and abundant nitric acid is produced by electrical storms. Our findings require improved NPF parameterization to be implemented in atmospheric models.
