10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
SALTENA Campaign: A Comprehensive Study of New Particle Formation (NPF) at Mt. Chacaltaya (5240m A.S.L.) in South America
QIAOZHI ZHA, Diego Aliaga, Otso Peräkyla, Yee Jun Tham, Xuemeng Chen, Joonas Enroth, Liine Heikkinen, Katrianne Lehtipalo, Juha Kangasluoma, Mikael Ehn, Mikko Sipilä, Tuukka Petäjä, Markku Kulmala, Claudia Mohr, Federico Bianchi, University of Helsinki
Abstract Number: 902 Working Group: Aerosol Chemistry
Abstract Atmospheric aerosol particles play an important role in the Earth’s radiation balance, and have a strong effect on climate. A significant contributor to atmospheric aerosol loading is new particle formation (NPF), which can produce up to 50% of the world’s cloud condensation nuclei (CCN). While fruitful results from field measurements have been reported over past decades, only a handful of studies have been conducted at high altitudes, where NPF events are frequently observed. Recent studies from Jungfraujoch station (3580m a.s.l.) in Central Europe reveal that NPF in the free troposphere was majorly driven by the condensation of highly oxygenated molecules (HOMs). However, the exact mechanism of free-tropospheric NPF in the Southern Hemisphere has remained unclear.
The ongoing Southern hemisphere high ALTitude Experiment on particle NucleAtion and growth (SALTENA) campaign started in December 2017, and is expected to finish in June 2018 in the Chacaltaya station (5240m, a.s.l.) in Bolivia. The station is approximately 30km away from city area of La Paz. A set of state-of-the-art instruments were deployed to systematically study the previously reported frequent NPF events. Information on the chemical composition of ion clusters was provided by an Atmospheric Pressure interface Time-Of-Flight mass spectrometer (APi-TOF). Atmospheric HOMs and sulfuric acid (SA) concentration were measured with a nitrate ion based Chemical Ionization APi-TOF (CI-APi-TOF). Aerosol chemical composition was measured with an Aerosol Chemical Speciation Monitor (ACSM). The concentration and size distribution of aerosol particles were measured with a particle size magnifier (PSM), a neutral cluster and air ion spectrometer (NAIS, also measuring ion cluster concentrations), and a scanning mobility particle sizer (SMPS). Trace gases, solar radiation, and meteorological parameters were also monitored.
Preliminary results from SALTENA show that NPF events are usually observed with the air masses originating from the city area, the air contained high SA concentrations and large amount of sulfuric acid-ammonia (SA+NH3) clusters, suggesting SA+NH3 nucleation might play an important role in such an environment. Nucleation could be also observed when air masses came from Amazon area, which involved abundant HOM molecules. In this presentation, a more detailed chemical analysis of the high altitude NPF events will be presented.