Understanding the Abundance, Variability and Sources of Ice NucleatingParticles (INPs) over the Kara and Laptev Seas in the Eurasian Arctic 

<p>The Arctic region is sensitive to climate change, experiencing accelerated warming. Cloud radiative properties and related feedback mechanisms on Arctic climate are highly uncertain and dependent on the cloud phase. Primary ice formation in Arctic mixed-phase clouds is initiated by INPs. So far, little is known regarding the abundance, variability, and potential sources of INPs in the Arctic owing to the scarcity of data, particularly in the marine environment. We study the INP-cloud interactions to improve the understanding of the abundance and sources of INPs in this region. &#160;We present results from a cruise-based Arctic Century Expedition, which took place from 5 August to 6 September 2021 in the previously uncharted Kara and Laptev Sea in the Eurasian Arctic. Ship-borne INP concentrations (immersion mode) and their spatiotemporal variabilities will be presented and linked to the physicochemical properties of ambient aerosols, including particle size distribution, heat lability, chemical compositions, and biological activities. Additionally, geographical variability of INPs along the ship track are investigated to assess the influence from different origins, e.g., sea ice, marine or terrestrial origins. Ultimately, we will report the results from the in-situ aerosol generator experiments to reveal the phase partitioning of INPs at the sea-air interface highlighting the importance of the aerosolization mechanisms to the production of marine INPs.</p>