Otso Peräkylä

Assistant Professor

E-Mail: otso.perakyla@nju.edu.cn

My research focuses on atmospheric oxidation and radical chemistry, particularly their role in secondary aerosol formation, air quality, and climate impacts. I am especially interested in oxidation of biogenic volatile organic compounds, and the chemistry of the organic peroxy radicals formed in the process.

My broader research interests include surface-atmosphere interactions, climate effects of land use, greenhouse gas exchange, and biogeochemical cycles. I also develop advanced tools for mass spectrometry data analysis. Beyond research, I am interested in the interface between science and policy, and in science communication.

Interested students are very welcome to contact me.

Professional Experience

Jan 2026 – Present: Assistant Professor, Nanjing–Helsinki Institute of Atmospheric and Earth System Sciences, Nanjing University

Sept. 2020 – Dec. 2025: Postdoctoral Researcher, Institute for Atmospheric and Earth System Research, University of Helsinki/Atmosphere and Climate Competence Center

Feb. 2023 – Dec. 2023: Scientific Expert, Climate Analytics Finland

Educational Background:

Sept. 2020 Doctor of Philosophy (with distinction), Atmospheric Science, University of Helsinki

Dec. 2015 Master of Science, Meteorology, University of Helsinki

Aug. 2014 Bachelor of Science, Meteorology, University of Helsinki

Research Interests:

Atmospheric Chemistry: Gas-phase chemistry of organic peroxy radicals, oxidation capacity of the atmosphere, formation of condensable vapours and secondary organic aerosol, and their climate impacts.

Climate and Land Use: Surface-atmosphere interactions, climate effects of land use, greenhouse gas sinks and sources.

Methods and Tools: Laboratory experiments and field measurements using mass spectrometry, data analysis tools.

Selected publications

Peräkylä, O. et al. (2023) “Large Gas-Phase Source of Esters and Other Accretion Products in the Atmosphere,” Journal of the American Chemical Society, 145(14), pp. 7780–7790. Available at: https://doi.org/10.1021/jacs.2c10398. We identified a new peroxy radical cross reaction pathway, forming covalently bound ester accretion products. These low-volatility esters are significantly more stable in aerosol phase than the previously known peroxides. They have often been found in aerosol samples, but with few plausible formation mechanisms up to now.

Peräkylä, O. et al. (2020) “Experimental investigation into the volatilities of highly oxygenated organic molecules (HOMs),” Atmospheric Chemistry and Physics, 20(2), pp. 649–669. Available at: https://doi.org/10.5194/acp-20-649-2020. For the first time, we experimentally quantified the volatilities of highly oxygenated organic compounds, allowing us to assess their important role in aerosol formation more precisely.

Peräkylä, O. et al. (2014) “Monoterpenes’ oxidation capacity and rate over a boreal forest: temporal variation and connection to growth of newly formed particles,” Boreal Environment Research, 19. Available at: http://hdl.handle.net/10138/165204. We used atmospheric measurements to construct time series for all major oxidants at a boreal forest site, through either direct measurements (for ozone), a simple proxy approach (for hydroxyl radical), or steady-state modelling (for nitrate radical), and linked nocturnal oxidation of monoterpenes to particle growth.

Peräkylä, O. et al. (2025) “Comparison of shortwave radiation dynamics between boreal forest and open peatland pairs in southern and northern Finland,” Biogeosciences, 22(1), pp. 153–179. Available at: https://doi.org/10.5194/bg-22-153-2025. We showed that snowmelt timing primarily determines the difference in annually absorbed shortwave energy between neighbouring open peatland and forest sites. We also found that forest management through thinning had a clear impact on the shortwave radiation balance in the winter, increasing absorbed solar radiation.

Zhang, Y., Peräkylä, O. et al. (2019) “A novel approach for simple statistical analysis of high-resolution mass spectra,” Atmospheric Measurement Techniques, 12(7), pp. 3761–3776. Available at: https://doi.org/10.5194/amt-12-3761-2019. We developed a new approach for mass spectral data analysis, where high-resolution information is directly utilised as input for factorisation, saving time and making the process less subjective. This approach enables much more efficient analysis of complex spectra.