Publications by authors named "H Junninen"

Aircraft observations have revealed ubiquitous new particle formation in the tropical upper troposphere over the Amazon and the Atlantic and Pacific oceans. Although the vapours involved remain unknown, recent satellite observations have revealed surprisingly high night-time isoprene mixing ratios of up to 1 part per billion by volume (ppbv) in the tropical upper troposphere. Here, in experiments performed with the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we report new particle formation initiated by the reaction of hydroxyl radicals with isoprene at upper-tropospheric temperatures of -30 °C and -50 °C.

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The ability of anthropogenic aerosols to freeze supercooled cloud droplets remains debated. In this work, we present observational evidence for the glaciation of supercooled liquid-water clouds at industrial aerosol hot spots at temperatures between -10° and -24°C. Compared with the nearby liquid-water clouds, shortwave reflectance was reduced by 14% and longwave radiance was increased by 4% in the glaciation-affected regions.

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Virucidal filter materials were prepared by electrospinning a solution of 28 wt % poly(vinylidene difluoride) in N,N-dimethylacetamide without and with the addition of 0.25 wt %, 0.75 wt %, 2.

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Article Synopsis
  • Researchers observed pure biogenic new particle formation (NPF) driven by highly oxygenated organic molecules (HOMs) in a peatland in southern Finland, indicating a possible mechanism for aerosol formation similar to pre-industrial times.
  • The study found that meteorological conditions created an "air pocket" at night, allowing NPF to initiate solely from biogenic HOM, providing a rare look at a pristine atmospheric environment.
  • This research offers insights into how pre-industrial aerosols were formed, helping improve our understanding of the effects of aerosols on climate today and in the future, especially as air pollution mitigation efforts may return conditions closer to those of the past.
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Risk assessment of pesticide impacts on remote ecosystems makes use of model-estimated degradation in air. Recent studies suggest these degradation rates to be overestimated, questioning current pesticide regulation. Here, we investigated the concentrations of 76 pesticides in Europe at 29 rural, coastal, mountain, and polar sites during the agricultural application season.

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