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Elucidating Processes Controlling Arctic Atmospheric Aerosol Sources, Aging, and Mixing States

Active Dates 9/1/2018-8/31/2024
Program Area Atmospheric System Research
Project Description
The objective of this project is to determine aerosol chemical composition, sources, mixing states, and aging processes across the entire annual cycle in the high Arctic, and in the Alaskan Arctic during fall – winter, to address the most significant gaps in Arctic aerosol observational data. The proposed project is based on the rapid sea ice loss across the entire Arctic, as well as the major delays in sea ice freeze-up in the Chukchi Sea, off the North Slope of Alaska (NSA). The project will: 1) Identify the sources of Arctic aerosols as a function of season, 2) Determine the mixing states and aging extents of Arctic aerosols as a function of season, and 3) Ascertain the most important factors (e.g., sea ice extent, radiation, meteorology) modulating the sources, chemical composition, mixing states, and aging processes of Arctic aerosols.

The proposed study will focus on analysis and interpretation of Atmospheric Radiation Measurement (ARM) field campaign samples and data collected during late fall/early winter at Utqiagvik, AK and during the year-long international Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) in the high Arctic. The project will use state of the art measurement techniques including real-time aerosol time of- flight mass spectrometry (ATOFMS), on-line aerosol sizing, and off-line computer-controlled scanning electron microscopy with energy-dispersive X-ray (CCSEM-EDX) spectroscopy. The project will provide an unparalleled opportunity to study seasonal changes in aerosol processes in the high Arctic. Size-resolved number fractions of observed individual particle sources will be determined for each month, with quantitation of locally emitted vs. long-range transported aerosols. Number fractions of aerosols internally mixed with various secondary species will be determined, and aerosol mixing state indices will be calculated. Sea ice extent and fracturing impacts on sea spray aerosol will be examined.

For predictions of Arctic atmospheric composition and feedbacks, knowledge of aerosol sources, mixing states, and aging processes is critical and is a significant current gap in our understanding of Arctic aerosols. The proposed project will provide unprecedented and critical knowledge of Arctic aerosol mixing states and processes. The overarching impact of the project will be the generation of Arctic aerosol observational data and improved understanding of Arctic aerosol processes to inform and evaluate future simulations of Arctic atmospheric composition and climate.
Award Recipient(s)
  • University of Michigan (PI: Pratt, Kerri)