AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Size-Dependent Nanoparticle Growth Profile from CLOUD Experiments
WEIMENG KONG, Stavros Amanatidis, Dongyu S. Wang, Loïc Gonzalez Carracedo, Birte Rörup, Dominik Stolzenburg, Jasper Kirkby, John Seinfeld, Richard Flagan, California Institute of Technology
Abstract Number: 344 Working Group: Aerosols, Clouds and Climate
Abstract New particle formation (NPF) from gaseous precursor vapors is frequently observed in the ambient environment and contributes to a major source of global cloud condensation nuclei (CCN). The survival and activation rate of newly formed particles are highly dependent on particle growth below 10 nm. Therefore, characterizing and understanding nanoparticle early growth can help to quantify the impact of NPF on the global CCN budget.
We performed a number of experiments under various atmospheric conditions in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN) to better understand NPF, particle growth and survival. Multiple experimental parameters were varied to study the influence of different highly oxygenated molecules (HOMs) and inorganic trace gases, such as ammonia and nitrogen oxides on particle early growth.
This work reports particle sizing and growth results measured by the Caltech nano- scanning electrical mobility analyzer (nSEMS), which measured continuous particle size distributions from 1.5 nm to 25 nm. The transfer function of nSEMS was derived based on electric and flow field simulations and validated with empirical measurements. Nanoparticle early growth was also modelled as gas-to-particle condensational growth to compare with experimental measurement. In order to capture the full picture of nanoparticle growth, survival and activation, size distribution information from the nSEMS were also compared and combined with other particle sizing instruments from CLOUD to obtain a continuous particle growth profile over the range from 1 nm to 500 nm.