MINC

Marine ARM GPCI Investigation of Clouds (MAGIC): Marine Ice Nuclei Collections

1 June 2013 - 30 September 2013

Lead Scientist: Paul DeMott

Observatory: AMF, MAG

This campaign augmented existing measurements obtained through the AMF deployment for the MAGIC field campaign with shipboard aerosol collections for offline processing to measure ice nuclei concentrations and their association with aerosol properties. A new data set was obtained for use toward parameterizing oceanic (e.g., sea spray) ice nuclei emissions in modeling of aerosol connections to cloud phase and properties on regional and global scales. Filter-based aerosol collections (24-hour samples) were made on at least four round-trip cruises from Los Angeles to Honolulu and archived frozen until post-analyses are completed. Offline analyses are expected to include measurements of the immersion freezing ice nuclei temperature spectra of particles washed from the filters, measurement of the concentrations of known ice-nucleating bacteria, processing to determine the inorganic/organic proportions of ice nuclei, and pyrosequencing analysis for association of ice nuclei with the overall biological community diversity. Correlations were examined with other aerosol parameters and meteorological data (e.g., wind speed) measured by the AMF, as well as with satellite ocean color products. We hypothesize that the release of ice nuclei from sea spray is a modest emission mechanism to the atmosphere, though greatly enhanced in water regions with strong marine biological activity and a control in any case on ice nuclei reaching mixed‐phase cloud levels directly over or after transport over expansive ocean areas. The MAGIC ice nuclei collections represent a critical in situ data set for characterizing ice nuclei concentrations over warmer and relatively lower productivity ocean regions for comparison to future data from other regions.