10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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New Particle Formation and Sub-10nm Size Distribution Measurements in Paphos, Cyprus, during the A-LIFE Field Experiment
SOPHIA BRILKE, Nikolaus Fölker, Konrad Kandler, Nan Ma, Thomas Müller, Anne Philipp, Thomas Ryerson, Petra Seibert, Bernadett Weinzierl, Paul M. Winkler, University of Vienna
Abstract Number: 1256 Working Group: Remote/Regional Atmospheric Aerosol
Abstract Atmospheric new particle formation (NPF) is a frequent phenomenon that is significantly contributing to the global aerosol budget throughout the troposphere. Newly formed particles can affect human health and potentially grow to sizes large enough to influence the Earth’s radiation balance and climate.
In this study, we aim at characterizing NPF and early nanoparticle growth in the Eastern Mediterranean region during the ERC-funded A-LIFE (Absorbing aerosol layers in a changing climate: aging, LIFEtime and dynamics) field experiment. The A-LIFE intensive measurement campaign in April 2017 combined in-situ and remote sensing measurement techniques both at the ground and on the Deutsches Zentrum für Luft- und Raumfahrt (DLR) research aircraft Falcon. The overall aim of A-LIFE is to study the properties of absorbing aerosols (i.e. mineral dust – black carbon mixtures) and investigate potential links between the presence of absorbing particles, aerosol layer lifetime and removal.
The understanding of the processes leading to NPF requires particle measurements down to the critical size of freshly formed particles. Sub-10nm particle size distribution measurements are extremely challenging due to high diffusional loss rates in the sampling and measurement system. Novel measurement techniques enable the detection of newly formed particles at a decent sensitivity: the DMA-train, designed for sub-10nm size distribution and precise growth rate measurements, was first set up in an atmospheric experiment. The DMA-train setup consists of six Differential Mobility Analysers (DMA) operated in parallel followed by condensation particle counters (CPCs) tuned for the detection of the smallest particle sizes at a time resolution of 1s with the lowest channel set at 1.8nm. The Scanning Mobility Particle Sizer (SMPS) scanned the size distribution onwards between 10 and 800nm in 5min intervals whereas the total particle concentration was obtained from a Particle Size Magnifier (PSM) - CPC combination every second.
During the 30-day measurement period at the coastal ground-based station in Paphos (Cyprus), we observed 9 NPF events during morning hours and were able to follow the initial particle growth in the DMA-train. In 5 cases, however, the initial growth was interrupted below 10nm and only 4 growth events were detected by the SMPS. This finding suggests that NPF may happen much more frequently than is currently thought but is oftentimes not captured well enough by regular SMPS. The local wind pattern is dominated by a land-sea-breeze system with NE and NW being the prevailing wind directions. The typical diurnal picture reveals highest total particle concentrations together with elevated NO/NO2 and SO2 concentrations for air masses carried to the station from the interior of the island during night hours. NPF events were found during both NE and NW wind situations. Furthermore, we use the FLEXPART (FLEXible PARTicle dispersion model) model in order to better understand on a large scale the origin of air masses that favour NPF.
In our presentation, we present results from the A-LIFE field experiment with the special focus on the parameters influencing NPF and initial particle growth in Cyprus. We will include size distribution data obtained by the DMA-train and correlations between particle and trace gas data as well as meteorological parameters. In addition, the backward trajectory analysis from FLEXPART and possible implications on NPF will be discussed.