Observations of atmospheric iodine-containing species during the MOSAiC expedition

The Arctic is a unique region featuring many environmental variations from a season to another. For example, sea ice is highly dynamic, with varying thickness and homogeneity, ultimately leading to open sea with a boost of biological activity during the warmest month. This, in turn, affects the emissions of gas-phase chemicals, potentially impacting New Particle Formation (NPF) and subsequent aerosol growth.

Several chemical vapors such as sulfuric acid (SA) and methane sulfonic acid (MSA) are known to possibly contribute to NPF and/or particle growth. Additionally, halogenated compounds, such as iodic acid, have recently revealed to be important for the formation of aerosol particles, especially in coastal and Arctic sites.

Few studies exist regarding direct measurements of iodic acid in the high Arctic, and none of them report multi-seasonal continuous observations - especially during the polar-night when the extremely low temperatures and the absence of solar radiation would likely prohibit any synthesis of such chemical species.

Here, we present our observations of iodine-containing vapors, principally iodic acid, as the result of continuous on-line measurements with the Nitrate based Chemical Ionization Atmospheric Pressure interface Time Of Flight Mass Spectrometer (NO₃-CI-APi-TOF-MS) during the whole Multidisciplinary Drifting Observatory of the Study of Arctic Climate (MOSAiC) expedition. In this study we combine and examine iodic acid multi-seasonal concentration time series in the central Arctic. In short, we aim at characterizing the observed iodic acid with the central Arctic environmental conditions (e.g., meteorological conditions, sea ice features and trace gases) and the linkage to NPF and particle growth.