Inhaltszusammenfassung

In the face of drastic climate changes in the Arctic (e.g., increasing near-surface air temperatures and sea ice loss), it is important to understand both key processes driving these changes and related future implications. The coupling of aerosol, clouds, and radiation plays an important role in the Arctic climate system. However, our knowledge of summertime Arctic aerosol and related processes is limited, in part owing to a lack of airborne observations in the Arctic summer. This study focu...In the face of drastic climate changes in the Arctic (e.g., increasing near-surface air temperatures and sea ice loss), it is important to understand both key processes driving these changes and related future implications. The coupling of aerosol, clouds, and radiation plays an important role in the Arctic climate system. However, our knowledge of summertime Arctic aerosol and related processes is limited, in part owing to a lack of airborne observations in the Arctic summer. This study focuses on natural and anthropogenic sources as well as formation processes controlling particle chemical composition in the summertime Arctic lower troposphere. Airborne in-situ measurements of aerosol particle chemical composition with diameters between 300 nm and 900 nm were performed in the Arctic summer using the single particle aerosol mass spectrometer ALABAMA. The ALABAMA particle composition analysis is complemented by trace gas measurements, satellite data, and air mass history modeling. Several pieces of evidence suggest the importance of both primary emissions and secondary processes in controlling the abundance of organic particulate matter in the summertime marine Arctic boundary layer. Single particle analysis shows that primary sea spray particles, including sodium, chloride, magnesium, and calcium, were internally mixed with organic matter. Alongside with these primary sea-to-air emissions, marine-biogenic sources contributed to secondary aerosol formation by trimethylamine, methanesulfonic acid, and/or sulfate. These particles were externally mixed from sea spray aerosol and their abundance correlated with time spent over Arctic open waters prior to sampling. In contrast, chemically aged particles, containing elemental carbon, nitrate, and/or dicarboxylic acids, dominated single particle composition above the Arctic boundary layer. The presence of these particle types was driven by transport of aerosol and precursor gases from mid-latitudes to Arctic regions. Based on air mass history analysis, mid-latitude sources included anthropogenic emissions in Europe, North America, and East Asia as well as vegetation fires in northern Canada. Together, these findings improve our knowledge of mid-latitude and regional sources that influence the vertical structure of aerosol properties in the Arctic summer. This work further provides new insights into the marine-biogenic control of composition and growth of summertime Arctic aerosol that is likely to change in future as sea ice retreats.» weiterlesen» einklappen

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Klassifikation

DDC Sachgruppe:
Naturwissenschaften