Study Design and First Results of the 2023 Soot-on-Snow Campaign
HANS MOOSMÜLLER, Jonas Svensson, Krista Luoma, Delun Li, Outi Meinander, Anna Kontu, Olli Sippula, Oona Norvapalo, Janne Jänis, Pavla Dagsson-Waldhauserová, Aki Virkkula,
Desert Research Institute Abstract Number: 524
Working Group: Aerosols, Clouds and Climate
AbstractFive Soot-on-Snow (SoS) experiments have been organized by the Finnish Meteorological Institute (FMI) since 2011 to study effects of soot deposition on snow optics and melting. Since 2013, SoS experiments were conducted at an abandoned airfield near FMI’s Sodankylä observatory in Lapland. In all experiments, soot particles are blown into chambers standing on top of the snow. After deposition, chambers are removed, and snow samples are taken from contaminated and reference snow spots and are analysed for elemental and organic carbon. The albedo of the snowpack is monitored over deposited and reference areas until snow melts out.
For the 2023 SoS experiments, directed by Virkkula, biomass-burning soot from burning real wood and peat and diesel soot from a diesel generator were used. The smoke is diluted and cooled down in large aluminium pipes covered with snow and finally injected into a chamber above the snow. Soot samples are taken both from the air blown into the chamber and from the snow after the deposition. These samples are analysed for UV-NIR absorption spectra of water-soluble organic carbon, methanol-soluble organic carbon, and elemental carbon to obtain the contribution of black and brown carbon to melting. Electron microscopy is utilized to study soot particles’ structural changes from fractal to more compact forms and chemical composition is analysed using mass spectrometry. Snow samples are taken several times a week after the initial deposition to observe aging. Snow physics measurements include spectral albedo, reflectance and transmittance spectra, snow grain size and type, density, and temperature.
This work was supported in part by the Academy of Finland project “Black and Brown Carbon in the Atmosphere and the Cryosphere” (No. 341271) and by the Broad Agency Announcement Program and the Cold Regions Research and Engineering Laboratory (ERDC-CRREL) under Contract No. W913E523C0002.