Formation and composition of the UTLS aerosol

Bengt G. Martinsson, Johan Friberg, Oscar S. Sandvik, Markus Hermann, Peter F.J. van Velthoven, Andreas Zahn

Research output: Contribution to journalArticlepeer-review

Abstract

Stratospheric aerosol has long been seen as a pure mixture of sulfuric acid and water. Recent measurements, however, found a considerable carbonaceous fraction extending at least 8 km into the stratosphere. This fraction affects the aerosol optical depth (AOD) and the radiative properties, and hence the radiative forcing and climate impact of the stratospheric aerosol. Here we present an investigation based on a decade (2005–2014) of airborne aerosol sampling at 9–12 km altitude in the tropics and the northern hemisphere (NH) aboard the IAGOS-CARIBIC passenger aircraft. We find that the chemical composition of tropospheric aerosol in the tropics differs markedly from that at NH midlatitudes, and, that the carbonaceous stratospheric aerosol is oxygen-poor compared to the tropospheric aerosol. Furthermore, the carbonaceous and sulfurous components of the aerosol in the lowermost stratosphere (LMS) show strong increases in concentration connected with springtime subsidence from overlying stratospheric layers. The LMS concentrations significantly exceed those in the troposphere, thus clearly indicating a stratospheric production of not only the well-established sulfurous aerosol, but also a considerable but less understood carbonaceous component.

Original languageEnglish
Article number40
Journalnpj Climate and Atmospheric Science
Volume2
Issue number1
DOIs
Publication statusPublished - 2019

Subject classification (UKÄ)

  • Meteorology and Atmospheric Sciences

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