East Asian SO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; pollution plume over Europe – Part 1: Airborne trace gas measurements and source identification by particle dispersion model simulations

V Fiedler,A Stohl,F Arnold,R Nau,H Schlager,S Ludmann

doi:10.5194/acp-9-4717-2009

Abstract

Abstract. A large SO2-rich pollution plume of East Asian origin was detected by aircraft based CIMS (Chemical Ionization Mass Spectrometry) measurements at 3–7.5 km altitude over the North Atlantic. The measurements, which took place on 3 May 2006 aboard of the German research aircraft Falcon, were part of the INTEX-B (Intercontinental Chemical Transport Experiment-B) campaign. Additional trace gases (NO, NOy, CO, H2O) were measured and used for comparison and source identification. The atmospheric SO2 mole fraction was markedly increased inside the plume and reached up to 900 pmol/mol. Accompanying lagrangian FLEXPART particle dispersion model simulations indicate that the probed pollution plume originated at low altitudes from densely populated and industrialized regions of East Asia, primarily China, about 8–12 days prior to the measurements.

Highlights

Atmospheric sulfur dioxide, SO2, represents a major air pollutant which has a profound impact on the environment
A large SO2-rich pollution plume of East Asian origin was detected by aircraft based chemical ionization mass spectrometry (CIMS) (Chemical Ionization Mass Spectrometry) measurements at 3–7.5 km altitude over the North Atlantic
Accompanying lagrangian FLEXPART particle dispersion model simulations indicate that the probed pollution plume originated at low altitudes from densely populated and industrialized regions of East Asia, primarily China, about 8–12 days prior to the measurements

Summary

Introduction

Atmospheric sulfur dioxide, SO2, represents a major air pollutant which has a profound impact on the environment. SO2 undergoes atmospheric chemical OH-induced conversion to sulfate via gaseous sulfuric acid, H2SO4, and thereby mediates formation of aerosol particles The new particles will grow further up to CCN (cloud condensation nuclei) size, if more condensable gases are available. This favors the formation of clouds and impacts the cloud droplet sedimentation lifetime. Recent model studies showed that most SO2 will survive upward transport in clouds (Kreidenweis et al, 1997; Crutzen and Lawrence, 2000) In addition it may undergo liquid-phase oxidation to condensed-phase sulfate which upon droplet water evaporation resides in the aerosol-phase (on average about 90% of all cloud droplets evaporate again).

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Conclusion