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It is estimated that about half of global cloud condensation nuclei might be formed in the atmosphere through new particle formation, i.e. formation of aerosol particles from gas-phase precursor vapors. For improving the description of secondary particle formation in global aerosol models, we need to improve the process understanding of new particle formation and growth, as well as the quantification of precursor vapors and particle formation rates. Measuring recently formed aerosol particles is difficult due to their extremely small size (< 2 nm in diameter), leading to high diffusivity and low charging probability. Methods for determining the concentration and size distribution of smallest aerosol particles are still under development, and there is a large uncertainty in the measurements. It is even a bigger challenge to quantify the aerosol precursor vapors (such as sulphuric acid, iodic acid and oxygenated organic vapors), as their concentrations in the atmosphere are typically very small (ppqv-level). Emerging methods, such as low-cut-off particle counters and high-resolution mass spectrometry needs to be further improved and standardized to respond to these challenges. The Institute for Atmospheric and Earth System Research at University of Helsinki is hosting two Central Facility units within ACTRIS (Aerosols, Clouds and Trace Gases Research Infrastructure). The Cluster Calibration Centre, part of the ACTRIS Centre for Aerosol In Situ Measurements (CAIS-ECAC), aims to standardize and validate the methods for measuring sub-10 nm particle concentration and size distribution. The CiGas-UHEL unit, part of ACTRIS Centre for Reactive Trace Gases In Situ Measurements (CiGas), aims to improve and develop calibration methods for detecting aerosol precursor vapors (condensable trace gases). Based on our long-term experience in conducting measurements of new particle formation both in field and laboratory, we have identified several development areas, which would advance the reliability of the measurements related to secondary particle formation. These include 1) developments in the instrumentation optimized for sub-10nm aerosol particles, as well as for the detection of precursor vapors, 2) developing standard operation procedures for the instrumentation currently in use, 3) improving the calibration and intercomparison methods and practices and finally 4) advancing the fundamental knowledge of the processes relevant to the measurements (e.g. aerosol charging probabilities, identities of the relevant precursor vapors and the effect of environmental conditions on the detection). Furthermore, development of advanced of the data products from open data (e.g. particle formation rates) would be highly beneficial for the community.
Topic : Theme 1: Atmospheric Chemistry and Physics.
Reference : T1-A43
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