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Composition and Distribution Analysis of Bioaerosols Under Different Environmental Conditions
Published on: January 7, 2019
Analysis and Optical Modeling of Individual Heterogeneous Asian Dust Particles Collected at Mauna Loa Observatory
Joseph M Conny1, Robert D Willis2, Diana L Ortiz-Montalvo1
1Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD, USA.
Journal of Geophysical Research. Atmospheres : JGR
|March 14, 2020
Summary
Asian dust particles containing iron oxides or soot significantly altered light scattering and extinction. These heterogeneous particles, originating from Asia, impacted optical properties differently than pure dolomite or calcite aerosols.
Area of Science:
- Atmospheric Science
- Aerosol Science
- Optical Physics
Background:
- Aerosol particles influence Earth's climate by scattering and absorbing solar radiation.
- Understanding the optical properties of heterogeneous aerosols is crucial for climate modeling.
Purpose of the Study:
- To determine the optical properties of heterogeneous aerosol particles collected at Mauna Loa Observatory.
- To investigate the impact of iron phases (oxide/carbonate) and soot on light extinction and scattering.
Main Methods:
- Aerosol sample collection at Mauna Loa Observatory.
- Scanning electron microscopy (SEM) for particle composition analysis.
- Focused ion-beam tomography and discrete dipole approximation (DDA) for optical property determination.
Main Results:
- Heterogeneous Asian dust particles showed lower extinction efficiencies than marine background aerosols.
- Iron oxides (hematite, magnetite) and soot significantly affected scattering, with absorbing iron oxides having a notable impact.
- Asian dust exhibited strong forward scattering, with backscattering enhanced by iron phases, particularly magnetite.
Conclusions:
- The presence of even small amounts of iron phases or soot alters the optical properties of Asian dust aerosols.
- Variations in particle orientation and inclusion phases lead to a range of scattering values.
- Accurate representation of heterogeneous aerosol composition is essential for climate models.
