Observations of atmospheric iodic acid over the one-year-long MOSAiC expedition in the central Arctic ; Jodihappohavainnot vuoden mittaisen MOSAiC-tutkimushankkeen aikana Arktiksella

The Arctic is warming approximately four times as fast as the rest of the planet, and the current and future changes may have drastic effects on the entire globe. However, the detailed processes of the Arctic climate have been studied to a small extent due to the remote and hard-to-reach location, and the representation of the Arctic in climate models has been inadequate. There are many uncertainties in climate models, and significant uncertainties concern aerosol-related information. Atmospheric aerosols have a large, yet not entirely understood and quantified effect on the climate. Aerosols affect the Earth’s radiative balance by scattering and absorbing incoming radiation, and they play a significant role in the cloud formation process. In order to improve the representation of the Arctic in climate models and tackle the unsolved questions about the Arctic atmosphere, sea ice, ocean, biogeochemistry and ecosystem, a one-year-long expedition called Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) was conducted in the central Arctic between September 2019 and October 2020. As secondary aerosol formation (new particle formation) produces more than 50% of the atmospheric cloud condensation nuclei, and iodic acid has been identified to be a significant compound for new particle formation in the Arctic pristine environments, the iodic acid concentrations during the full-year MOSAiC expedition was investigated. The main research objective was to quantify the seasonal cycle of iodic acid in the Arctic. The correlation with temperature, solar radiation and ozone were also studied. Together with ice dynamics, sea ice thickness and air mass back trajectory simulations, the possible sources of measured iodic acid were investigated. The participation in forming new particles was also studied. The measured iodic acid concentrations varied between 1e4 and 4e7 molecules/cm3 with a detection limit of 1.22e5 molecules/cm3, and the concentrations were in the same range with measured earlier in the ...