Influence of vegetation on occurrence and time distributions of regional new aerosol particle formation and growth.

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From: Atmospheric Chemistry and Physics(Vol. 21, Issue 4)
Publisher: Copernicus GmbH
Document Type: Article
Length: 414 words

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Abstract :

The occurrence frequency of regional atmospheric new aerosol particle formation and consecutive growth events (f.sub.NPF) were studied with respect to vegetation activity, aerosol properties, air pollutants and meteorological data in Budapest over the time interval from 2008 to 2018. The data set evaluated contained results of in situ measurements on the land surface that were mostly performed at the Budapest platform for Aerosol Research and Training Laboratory, of satellite-based products recorded by MODIS on Terra and of modelled vegetation emission-related properties from an advanced regional biogeochemical model. The annual mean relative occurrence frequencies were considerable (with an overall mean of 21 %), remained at a constant level (with an overall SD of 5 %) and did not exhibit tendentious change over the years. The shape of the distributions of monthly mean f.sub.NPF exhibited large variability from year to year, while the overall average distribution already possessed a characteristic pattern. The structure of the new particle formation (NPF) occurrence distributions was compared to those of environmental variables including concentrations of gas-phase H.sub.2 SO.sub.4, SO.sub.2, O.sub.3, NO, NO.sub.2, CO, PM.sub.10 mass and NH.sub.3 ; particle numbers in the size fractions of 6-1000, 6-100 and 100-1000 nm; condensation sink; air temperature (T); relative humidity (RH); wind speed (WS); atmospheric pressure (P); global solar radiation (GRad); gross primary production (GPP) of vegetation; leaf area index (LAI); and stomatal conductance (SCT). There were no evident systematic similarities between f.sub.NPF on the one hand and all of the variables studied on the other hand, except for H.sub.2 SO.sub.4 and perhaps NH.sub.3 . The spring maximum in the NPF occurrence frequency distribution often overlapped with the time intervals of positive T anomaly in vegetated territories. The link between the potential heat stress exerted on plants in sultry summer intervals and the summer f.sub.NPF minimum could not be proven. The relevance of environmental variables was assessed by their ratios on NPF event days and on non-event days. The gas-phase H.sub.2 SO.sub.4 concentration showed the largest monthly ratios, followed by O.sub.3 . The WS, biogenic precursor gases and SO.sub.2 can generally favour NPF events, although their influence seemed to be constrained. An association between the f.sub.NPF and vegetation growth dynamics was clearly identified.

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Gale Document Number: GALE|A653037240