The contribution of sulphuric acid to atmospheric particle formation and growth: a comparison between boundary layers in Northern and Central Europe

[摘要] Atmospheric gaseous sulphuric acid was measured and its influence on particle formation and growth wasinvestigated building on aerosol data. The measurements were part of the EU-project QUEST and took place at twodifferent measurement sites in Northern and Central Europe (Hyytiälä, Finland, March-April 2003 andHeidelberg, Germany, March-April 2004). From a comprehensive data set including sulphuric acid, particle numbersize distributions and meteorological data, particle growth rates, particle formation rates and source rates ofcondensable vapors were inferred. Growth rates were determined in two different ways, from particle sizedistributions as well as from a so-called timeshift analysis. Moreover, correlations between sulphuric acid andparticle number concentration between 3 and 6 nm were examined and the influence of air masses of differentorigin was investigated. Measured maximum concentrations of sulphuric acid were in the range from1x10⁶ to 16x10⁶cm^-3. The gaseous sulphuric acid lifetime with respect tocondensation on aerosol particles ranged from 2 to 33min in Hyytiälä and from 0.5 to 8 min inHeidelberg. Most calculated values (growth rates, formation rates, vapor source rates) were considerably higherin Central Europe (Heidelberg), due to the more polluted air and higher preexistent aerosol concentrations.Close correlations between H₂SO₄ and nucleation mode particles (size range: 3-6 nm) were found onmost days at both sites. The percentage contribution of sulphuric acid to particle growth was below 10% atboth places and to initial growth below 20%. An air mass analysis indicated that at Heidelberg new particleswere formed predominantly in air advected from southwesterly directions.

[学科分类] 大气科学