EGU24-8668, updated on 08 Mar 2024
https://doi.org/10.5194/egusphere-egu24-8668
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Effect of long-range transported fire emissions on aerosol and cloud properties at high latitudes: In situ measurements and satellite observations

Snehitha M. Kommula1, Angela Buchholz1, Yvette Gramlich2,3, Tero Mielonen4, Liqing Hao1, Iida Pullinen1, Lejish Vettikkat1, Jorma Joutsensaari1, Siegfried schobesberger1, Petri Tiitta4, Ari Leskinen1,4, Dominic Heslin Rees2,3, Sophie Haslett2,3, Karolina Siegel2,3, Chris Lunder5, Paul Zieger2,3, Radovan Krejci2,3, Sami Romakkaniemi4, Claudia Mohr6,7, and Annele Virtanen1
Snehitha M. Kommula et al.
  • 1University of Eastern Finland, Department of Technical Physics, Kuopio, Finland (snehitha.kommula@uef.fi)
  • 2Department of Environmental Science, Stockholm University, Stockholm, 11418, Sweden
  • 3Bolin Centre for Climate Research, Stockholm University, Stockholm, 11418, Sweden.
  • 4Finnish Meteorological Institute, Yliopistonranta 8, FI-70210, 7 Kuopio, Finland
  • 5The climate and environmental research institute NILU, PO Box 100, 2027 Kjeller, Norway
  • 6Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Villigen, Switzerland
  • 7Department of Environmental System Science, ETH Zurich, Switzerland

Global warming and climate change-induced rise in Earth’s temperature have increased the frequency of forest/wildfires over the past decade. Therefore, understanding the effect of fire emissions on aerosol-cloud interactions is crucial for improving Earth system models.

         We present observations from in-situ measurements of aerosol properties at the Puijo SMEAR IV station in eastern Finland and the Zeppelin Observatory in Ny-Ålesund, High Arctic. Both stations are frequently inside low-level clouds due to their topographic prominence. During the autumn of 2020, fire emissions from the same active fire region in south-eastern (SE) Europe reached both stations after ~2 - 8 days of atmospheric aging. This enabled us to investigate the changes in aerosol and cloud properties for clouds formed under the influence of aged fire emissions (referred to as the ‘fire’ period) and under cleaner conditions with no fire emission influence at these stations (‘non-fire’ period). The aerosol hygroscopicity parameter (κchem) was derived from the chemical composition data obtained from online aerosol mass spectrometers and was used to derive the number concentration of cloud condensation nuclei (NCCN) from the measured particle size distributions.

         At both stations, the aerosol number concentration in the accumulation mode and the cloud condensation nuclei concentration (NCCN) were higher during the fire period than during non-fire times. However, the aerosol hygroscopicity increased at Puijo but decreased a Zeppelin from the non-fire to fire period. At Puijo, in-situ measured cloud droplet number concentration (CDNC) was by a factor of ~7 higher when comparing fire to non-fire periods. This was in good agreement with the satellite observations (MODIS, Terra). At Puijo, the higher CCN concentrations during the fire period cause a depletion of the water vapor available for cloud droplet activation leading to larger observed activation diameters during cloud events despite the higher hygroscopicity of the aerosol particles.

         These observations show the importance of SE European fires for enhancing the CCN activity in Finland and the high Arctic. Results from this study emphasize the complex interplay between particle size and chemical composition, and how fires even from sources far away can have strong impacts in these remote regions.

How to cite: Kommula, S. M., Buchholz, A., Gramlich, Y., Mielonen, T., Hao, L., Pullinen, I., Vettikkat, L., Joutsensaari, J., schobesberger, S., Tiitta, P., Leskinen, A., Rees, D. H., Haslett, S., Siegel, K., Lunder, C., Zieger, P., Krejci, R., Romakkaniemi, S., Mohr, C., and Virtanen, A.: Effect of long-range transported fire emissions on aerosol and cloud properties at high latitudes: In situ measurements and satellite observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8668, https://doi.org/10.5194/egusphere-egu24-8668, 2024.

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