C044-0004
Springtime observations of ice nucleating particles (INP) above Arctic sea ice during MOSAiC
Monday, 14 December 2020
Poster
Markus M Frey1, Amelie Kirchgaessner1, Tom Lachlan-Cope1, Frank Sagan2, Martin Radenz3, Frank Stratmann3, Amy Macfarlane4, Stefanie Arndt5, Kouichi Nishimura6, Ian M. Brooks7, Anna E. Jones1 and Xin Yang1, (1)NERC British Antarctic Survey, Cambridge, United Kingdom, (2)Droplet Measurement Technologies, Boulder, United States, (3)Leibniz Institute for Tropospheric Research, Leipzig, Germany, (4)WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland, (5)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany, (6)Nagoya University, Nagoya, Japan, (7)University of Leeds, Leeds, United Kingdom
Abstract:
Arctic clouds are poorly represented in climate models partly due to a lack of understanding of source and nucleating capability of natural aerosol in the high Arctic. Recent field campaigns provided evidence of a hypothesised source of sea salt aerosol (SSA) from blowing snow (BSn) above sea ice, which can account for SSA winter/spring time maxima observed in the polar regions. SSA emissions from sea ice sources contribute to the Arctic background aerosol budget, but can also influence regional climate via the indirect radiative effect. However, the role of SSA from sea ice related sources as a contributor to cloud condensation nuclei (CCN) and ice-nucleating particles (INP) and impacts on low-level cloud formation are only poorly known. The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition afforded the unique opportunity to study processes related to cloud forming particles above sea ice, and investigate the interactions between sea ice, snow and the lower atmosphere up to heights where clouds form.
Here we report the first online spring-time observations of INPs above sea ice during April to mid-May 2020 using the continuous flow diffusion chamber SPIN (SPectrometer for Ice Nuclei, DMT). The instrument was operated from the bow of RV Polarstern in the BAS Container Laboratory at approximately 15m above the sea ice in the temperature range -15 to -38 °C. Significant INP concentrations on the order of 10s m-3 were detected at -15 and -20 °C regardless of Northerly or Southerly air mass influence and often associated with high wind speeds. We discuss the role of sea ice including open leads and blowing snow as a source of INPs in Arctic spring and potential impacts on clouds. To do this we take into account concurrent in situ measurements of surface snow physical properties, atmospheric snow particles (size 50-500 µm), coarse aerosol (size 0.4-40 µm) as well as cloud occurrence and phase.
