Arctic Absorbing Aerosols and Albedo of Snow (A4)

The main objective of the project is to quantify the interaction of Arctic snow albedo and absorbing aerosols (Black Carbon, BC), and to gain more in-depth understanding of the globally important aspects of BC and albedo feedback, as well as BC and snow melt in the Arctic.


Funding: Academy of Finland (decision No. 254195)
Start year: 2012
End year: 2015
Coordinating: Finnish Meteorological Institute (FMI)

Contact: Prof. Gerrit de Leeuw (, and Outi Meinander (
Partners and co-operation: The project is within the Nordic Top-level Research Initiative (TRI) "Cryosphere-atmosphere interactions in a changing Arctic climate" (CRAICC) with ACP CRAICC –Special Issue.


Black carbon (BC) is formed through the incomplete combustion of fossil fuels, forest fires, industrial processes, diesel vehicles, and other sources of incomplete combustion emitting soot particles to the atmosphere. The effect of BC in snow layers is of importance to climate change and also for forcasting snow melt.

Snow reflectivity, i.e. albedo, varies with wavelength, and therefore the strength of the feedback depends on a number of factors, such as the depth and age of the snow cover, snow grain size, solar zenith angle, and cloud cover. According to IPCC, the level of scientific understanding on the effect of BC on surface albedo (black carbon aerosol on snow) is low, the consensus insufficient, and the evidence for radiative forcing estimates not strong.

Uncertainties are identified there to be especially related to: separation of anthropogenic from natural,  mixing of snow and aerosols, and quantification of radiative forcing. Especially the effect of black carbon on snow albedo and melting is improperly understood. Our work aims to reduce these uncertainties.

Publications with A4 project in the acknowledgements:

The whole list of A4 publications, presentations and press releases: The most recent is:

Meinander et al. 2013, ACP, Citation: Meinander, O., Kazadzis, S., Arola, A., Riihelä, A., Räisänen, P., Kivi, R., Kontu, A., Kouznetsov, R., Sofiev, M., Svensson, J., Suokanerva, H., Aaltonen, V., Manninen, T., Roujean, J.-L., and Hautecoeur, O.: Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle, Atmos. Chem. Phys., 13, 3793-3810, doi:10.5194/acp-13-3793-2013, 2013.


Last updated: 5 March.2014 by Outi Meinander