Single Particle Characterization of Free Tropospheric Aerosols at the Pico Mountain Observatory over the North Atlantic
Claudio Mazzoleni1, Swarup China2, Barbara V Scarnato3, Ryan Moffet4, Rachel E O'Brien5, Mary Kathleen Gilles6, Paulo JLCS Fialho7, Marian Ampadu2, Sumit Kumar2, Katja Dzepina2, Kendra Wright2, Noopur Sharma2, Bo Zhang8, Robert Chris Owen2,9, Judith A Perlinger10, Hueber Jacques11, Dr. Detlev Helmig11, Michael Dziobak2, Louisa J Kramer2 and Lynn R Mazzoleni2, (1)Michigan Technological University, Physics, Houghton, MI, United States, (2)Michigan Technological University, Houghton, MI, United States, (3)Naval Postgraduate School, Monterey, CA, United States, (4)University of the Pacific, Stockton, CA, United States, (5)University of the Pacific, Department of Chemistry, Stockton, CA, United States, (6)Lawrence Berkeley National Lab, Berkeley, CA, United States, (7)University of the Azores, Azores, Portugal, (8)Michigan Technological University, Houghton, United States, (9)Environmental Protection Agency Research Triangle Park, Research Triangle Park, NC, United States, (10)Michigan Technological University, Atmospheric Sciences and Department of Civil & Environmental Engineering, Houghton, MI, United States, (11)University of Colorado at Boulder, Institute of Arctic and Alpine Research, Boulder, CO, United States
Abstract:
Free tropospheric aerosols are being studied at the Pico Mountain Observatory, located near the top of the Pico volcano in the Azores, Portugal (38.47°N, 28.40°W, 2225m asl). Typically above the marine boundary layer in the summer, this is an ideal site to study aerosol transported over long distances across the Atlantic Ocean. Aerosols reaching the Observatory often originate from North America and sometimes from Africa and Europe. Aerosols instrumentation deployed at the site include: a) an optical particle counter, b) a 7-wavelength aethalometer to measure black carbon equivalent mass concentration, c) a 3-wavelength nephelometer to measure total and backward light scattering, d) four high volume samplers for aerosol chemical characterization, and e) a sequential aerosol sampler and a 4-stage impactor to collect particles on different substrates for microscopy analysis. The origin and transport pathways of the air masses sampled at the site are determined using FLEXible PARTicle (FLEXPART) dispersion modeling retroplume analysis. Single particle morphology and mixing states were determined using electron microscopy, energy dispersive X-ray spectroscopy, and scanning transmission x-ray microscopy.
This study provides an overview of different types of aerosol collected at Pico Mountain Observatory. We investigated morphology and mixing of various types of particles, including dust, soot, salt and organic particles transported to the Observatory. Soot particles were often mixed/coated with other material and exhibited very compact shape. Dust particles were often mixed with sulfur containing species. We also observed dust particles that were mixed with coated soot particles. During some events, we observed soot and sulfate aerosol trapped within organic matter. The results of this study have implications on how aerosol particles and their internal mixing can be represented in numerical models for remote regions of the free troposphere.
