Prof. Mikko Sipilä (University of Helsinki, Finland)

 Secondary aerosol particles that form from atmospheric vapours via nucleation and condensation represent a major fraction on cloud condensation nuclei (CCN) in Arctic and Antarctic polar atmospheres. Natural biogenic emissions of sulphur, iodine and volatile organic compounds (VOC), and – in the Arctic - also anthropogenic long range transported air pollutants are oxidized in the atmosphere to form condensable particle precursor vapours, such as sulfuric acid, iodic acid, highly oxidized organic vapours (HOM) etc. These vapours may nucleate, often via ion induced mechanism, and grow by condensation to climatically relevant sizes where they can act as CCN and modify cloud properties and Earth’s radiative budget.
I will summarize the latest results and knowledge on mechanisms and pathways that lead from biogenic emissions to condensable vapours, molecular clusters, aerosols and CCN in the polar lower troposphere and discuss the open questions and related future research needs in the high latitudes.

Professor Mikko Sipilä is the head of the Värriö research station at the University of Helsinki in Salla, Finnish Lapland. His research interests range from atmospheric composition to climate change and biodiversity loss. He has mainly investigated the mechanisms of secondary aerosol formation, especially in the polar and northern boreal environments. He has also been involved in the development of measurement technology, such as condensation particle counters and chemical ionization mass spectrometers.

Physicum seminars are meant for a broad auditorium of physicists and materials scientists, as well as for interested people from other natural and exact sciences (including bachelor level students) and aim at introducing what is important and new in a certain field, or where a specific research direction has reached today.

Seminar is in English! Everybody is welcome to attend.