Direct effect of aerosols on solar radiation and gross primary production in boreal and hemiboreal forests

Ekaterina Ezhova, Ilona Ylivinkka, Joel Kuusk, Kaupo Komsaare, Marko Vana, Alisa Krasnova, Steffen Noe, Mikhail Arshinov, Boris Belan, Sung-Bin Park, Jost Valentin Lavric, Martin Heimann, Tuukka Petäjä, Timo Vesala, Ivan Mammarella, Pasi Kolari, Jaana Bäck, Ullar Rannik, Veli-Matti Kerminen, Markku Kulmala

Research output: Contribution to journalArticleScientificpeer-review


The effect of aerosol loading on solar radiation and the subsequent effect on photosynthesis is a relevant question for estimating climate feedback mechanisms. This effect is quantified in the present study using ground-based measurements from five remote sites in boreal and hemiboreal (coniferous and mixed) forests of Eurasia. The diffuse fraction of global radiation associated with the direct effect of aerosols, i.e. excluding the effect of clouds, increases with an increase in the aerosol loading. The increase in the diffuse fraction of global radiation from approximately 0.11 on days characterized by low aerosol loading to 0.2-0.27 on days with relatively high aerosol loading leads to an increase in gross primary production (GPP) between 6% and 14% at all sites. The largest increase in GPP (relative to days with low aerosol loading) is observed for two types of ecosystems: a coniferous forest at high latitudes and a mixed forest at the middle latitudes. For the former ecosystem the change in GPP due to the relatively large increase in the diffuse radiation is compensated for by the moderate increase in the light use efficiency. For the latter ecosystem, the increase in the diffuse radiation is smaller for the same aerosol loading, but the smaller change in GPP due to this relationship between radiation and aerosol loading is compensated for by the higher increase in the light use efficiency. The dependence of GPP on the diffuse fraction of solar radiation has a weakly pronounced maximum related to clouds.
Original languageEnglish
JournalAtmospheric Chemistry and Physics
Issue number24
Pages (from-to)17863-17881
Number of pages19
Publication statusPublished - 17 Dec 2018
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 1171 Geosciences
  • 1172 Environmental sciences

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