Collaborative Research: Antarctic Low Cloud Interaction with Natural Aerosol (ALCINA)

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Global climate model simulations are one of the most important tools for predicting Earth’s future climate in response to changing greenhouse gas concentrations or changes in incoming solar energy. Climate simulations over Antarctica and the Southern Ocean can be improved by better physical representation of low-level clouds, which have large impacts on ice surface melt events and inaccuracies in solar energy transmission, which degrades weather models. Errors in cloud simulations have been linked to insufficient information about aerosols - the ubiquitous microscopic particles that seed cloud droplet and cloud ice crystal formation. This project will collect data on aerosol chemical and microphysical properties simultaneously with cloud optical properties at Palmer Station continuously for 18 months, sampling aerosols sourced from both the ocean and from the continent. For broader impacts, the field campaigns involve diverse lead scientists and early career researchers and will engage in public outreach seminars through the School of Global and Environmental Sustainability’s Antarctic Lecture Series. Scientific activities from this project will be incorporated into the California Next Generation Science Standards through a partnership with the California Association for Science Educators.This project will deploy a combination of advanced aerosol sampling equipment and cloud remote sensing and surface radiation instruments that will operate for an extended duration at Palmer Station. Encompassing all seasons including two austral summers, these new observations will yield robust aerosol-cloud interaction (ACI) statistics for climate model evaluation and improvement. Aerosol property measurements include size distributions, number concentrations of cloud condensation nuclei (CCN) and ice nucleating particles (INPs), chemical composition including mineral, sulfate, sea salt and organics, and microbial community structure from DNA sequencing. The observations will span orders of magnitude changes in aerosol number concentrations and chemical constituents resulting from the strong seasonal cycle of biogenic activity and from changing airmass origins. These new measurements will also differentiate between influences of algal blooms and continental dust on INPs, for which there is presently a great scarcity of data over Antarctica. Atmospheric observations include near-infrared spectroscopic measurement of cloud liquid water content and effective liquid water droplet and ice crystal particle size, cloud base height and geometrical thickness, and surface energy budget components. These observations will be supplemented by satellite remote sensing of cloud properties from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS), the NASA Cloud and land Elevation Satellite (ICESat-2), and the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Soumi National Polar-orbiting Partnership (SNPP) and NOAA-20 satellites. This project was co-funded by the Division of Atmospheric and Geospace Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.