New Particle Formation in Polluted Atmospheres by Nanocluster Dynamics Assessment

ended

NPF-PANDA aims for a multi-method assessment of cluster dynamics in urban environments during new particle formation. New particle formation by gas-to-particle conversion is frequently detected in the atmosphere, but, according to the current understanding, should not proceed in heavily polluted urban areas, where large amounts of primary aerosol particles are present acting as sink for both condensable vapours and newly formed clusters. However, it is nonetheless observed in Chinese megacities where it even can promote haze formation and hence impact urban air quality. It is under debate, whether this is linked to faster cluster growth or a less effective condensation sink than commonly assumed. NPF-PANDA will quantify urban cluster size-distributions below 3 nm with a multi-instrument approach and novel data analysis methods. This will lead to unprecedented high quality data of the cluster dynamics and solve the role of fast growth on the survival probability of newly formed clusters under high condensation sink. By combining measurements from urban Beijing with precisely tailored laboratory experiments at the CERN CLOUD chamber, the magnitude of the underlying microphysical growth processes like coagulation or condensation will be disentangled and the effects of different precursor gases can be tested. Cluster dynamics simulations will back-up the experimental findings and via a detailed comparison of measured and simulated size-distributions, this will reveal information on cluster stability and the cluster-stabilizing role of different bases. Altogether, the project will be an essential part in solving the “China-NPF-puzzle” and hence impact future air quality research and air pollution mitigation, which is also highly relevant for medium-polluted European cities.