Abstract

[1] Extensive measurements of black carbon (BC) aerosol were conducted in and near the North American Arctic during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) aircraft campaign in April and June–July 2008. We identify the pathways and mechanisms of transport of BC to the Arctic from the Asian continent using these data. The concentration, transport efficiency, and measured altitude of BC over the North American Arctic were highly dependent on season and origin of air parcels, e.g., biomass burning (BB) in Russia (Russian BB) and anthropogenic (AN) in East Asia (Asian AN). Russian BB air was mainly measured in the middle troposphere and caused maximum BC concentrations at this altitude in spring. The median BC concentration and transport efficiency of the Russian BB air were 270 ng m−3 (at STP) and 80% in spring and 20 ng m−3 and 4% in summer, respectively. Asian AN air was measured most frequently in the upper troposphere, with median values of 20 ng m−3 and 13% in spring and 5 ng m−3 and 0.8% in summer. These distinct differences are explained by differences in the transport mechanisms and accumulated precipitation along trajectories (APT), which is a measure of wet removal processes during transport. The transport of Russian BB air to the Arctic was nearly isentropic with slow ascent (low APT), while Asian AN air underwent strong uplift associated with warm conveyor belts (high APT). The APT values in summer were much larger than those in spring due to the increase in humidity in summer. These results show that the impact of BC emitted from AN sources in East Asia on the Arctic was very limited in both spring and summer. The BB emissions in Russia in spring are demonstrated to be the most important sources of BC transported to the North American Arctic.

Highlights

  • [2] In the Arctic, high concentrations of aerosols and reactive gases, so‐called Arctic haze, occur in winter and [3] Previous studies have estimated the source regions of Arctic pollution using trajectory, regional, and global models

  • [7] In this study, we focus on black carbon (BC) transport from the Asian continent (Russia and East Asia (China, Japan, and Korea)) to the Arctic because the Aircraft and Satellites (ARCTAS) measurements were made mainly over the Alaskan region, which received BC mostly originating from Asia [Fuelberg et al, 2010]

  • [40] We have quantified the pathways and efficiencies of BC transport from different regions and fuel types of combustion (anthropogenic (AN) and biomass burning (BB)) to the Arctic region using data obtained by the ARCTAS aircraft campaign conducted in April and June–July 2008

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Summary

Introduction

[2] In the Arctic, high concentrations of aerosols and reactive gases, so‐called Arctic haze, occur in winter and. Studies using trajectory [Stohl, 2006; Law and Stohl, 2007] and regional chemical transport models [Klonecki et al, 2003] estimated that northern Eurasia (Europe and Siberia) is the major source of Arctic haze in the lower troposphere (LT). Koch and Hansen [2005] estimated using the Goddard Institute for Space Studies (GISS) general circulation model (GCM) that south Asia becomes the dominant source region of BC in the upper troposphere (UT) (30–50%) in the Arctic and contributes significantly to Arctic haze near the surface. Shindell et al [2008] conducted a multimodel comparison of aerosol transport to the Arctic and showed large differences in the calculated BC concentrations in the Arctic by the different GCM models used in the IPCC report.

Measurements and the Methods of Analysis
Findings
Summary and Conclusion
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