AAAR 28th Annual Conference

AAAR Tutorial Sessions

Monday, October 26, 2009

First Session: 8:00 a.m. - 9:40 a.m.

1. 1. INTRODUCTION TO AEROSOL MECHANICS I

   Richard C. Flagan, Department of Chemical Engineering, California Institute of Technology, Pasadena, CA

   Abstract: These two courses (Tutorials 1 and 5) form a sequence that covers basic aerosol mechanics (particle motion) at an introductory level. Topics include: Stokes law, settling velocity, slip correction, aerodynamic diameter, non-spherical particles, acceleration, relaxation time, stopping distance, impaction, isokinetic sampling, diffusion, condensation, and coagulation. The course covers theory and applications and is suitable for those new to the field and for others who want to brush up on the basics.

   Richard C. Flagan is the McCollum/Corcoran Professor at the California Institute of Technology where he teaches chemical engineering and environmental science. He has served as president of AAAR and editor-in-chief of Aerosol Science and Technology. His research spans the field of aerosol science, including atmospheric aerosols, aerosol instrumentaton, aerosol synthesis of nanoparticles and other materials, and bioaerosols. His many contributions to the field of aerosol science have been acknowledged with the Sinclair Award of the AAAR and the Fuchs Award.

2. 2. MINERAL DUST AEROSOL: PROPERTIES, LIFECYCLE, AND IMPACTS

   Irina N. Sokolik, School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA

   Abstract: Because of its complex nature, mineral dust presents a particularly difficult challenge in assessments of its impact on air quality, atmospheric chemistry, cloud formation, and climate. This tutorial will cover the following topics: recent advances in measurements and modeling of physical, chemical and optical properties of dust particles; production, transport and removal processes; dust interactions with clouds and precipitation; and radiative impacts of dust on the Earth's energy balance and climate. In addition, a summary of representation of dust in regional and global climate models and current capabilities of passive and active remote sensing of dust will be provided.

   Irina N. Sokolik is a professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology. She received a masters degree in atmospheric physics from the Moscow Institute of Physics and Technology in 1984 and a doctorate degree in atmospheric physics from the Russian Academy of Sciences in 1989. She has a multi-year experience in studying dust aerosol across a broad spectrum of applications.

3. 3. ANALYTICAL METHODS FOR ASSESSING BIOAEROSOL EXPOSURES

   Tiina Reponen, Department of Environmental Health, University of Cincinnati, Cincinnati, OH

   Abstract: Bioaerosols include viruses, bacteria, fungi, pollen, and their fragments as well as animal allergens. The size of biological particles varies widely, from nano-scale (virions and microbial fragments) to about 100 µm (pollen grains). The same physical principles that are applied to non-biological particles can be applied to bioaerosol sampling in terms of sampling efficiency of a given particle size range. When conducting exposure assessment for bioaerosols, one has to consider what biological properties would be the most relevant measures for the health outcome in question. This tutorial will review the traditional and modern techniques for the analysis of bioaerosol samples. Advantages and disadvantages of various methods and future direction in bioaerosol exposure assessment will be discussed.

   Tiina Reponen is a professor of environmental health at the University of Cincinnati, Department of Environmental Health. She received her doctoral degree in environmental sciences from Kuopio University, Finland. Her current research efforts are focused on the exposure assessment of biological and non-biological particles in indoor and industrial environments and on respiratory protection against bioaerosol particles.

4. 4. SECONDARY AEROSOL FORMATION

   Paul J. Ziemann, Air Pollution Research Center and Department of Environmental Sciences, University of California, Riverside, CA

   Abstract: Secondary aerosol is an important component of atmospheric fine particles that generally consists of organics, sulfates, and nitrates. The processes that lead to the formation of this material are often complex and can involve gas and particle phase chemistry, nucleation, and gas-particle partitioning. In this course Dr. Ziemann will discuss the major chemical reactions and partitioning processes involved in the formation of secondary organic and inorganic aerosol (with a strong emphasis on organic aerosol) using examples from laboratory and field studies.

   Paul J. Ziemann is a professor of atmospheric chemistry at the University of California, Riverside. He received a doctorate in chemistry from Penn State University and was a postdoctoral researcher in the Particle Technology Laboratory at the University of Minnesota.

Second Session: 10:00 a.m. - 11:40 a.m.

1. 5. INTRODUCTION TO AEROSOL MECHANICS II

   Richard C. Flagan, Department of Chemical Engineering, California Institute of Technology, Pasadena, CA

   Abstract: These two courses (Tutorials 1 and 5) form a sequence that covers basic aerosol mechanics (particle motion) at an introductory level. Topics include: Stokes law, settling velocity, slip correction, aerodynamic diameter, non-spherical particles, acceleration, relaxation time, stopping distance, impaction, isokinetic sampling, diffusion, condensation, and coagulation. The course covers theory and applications and is suitable for those new to the field and for others who want to brush up on the basics.

   Richard C. Flagan is the McCollum/Corcoran Professor at the California Institute of Technology where he teaches chemical engineering and environmental science. He has served as president of AAAR and editor-in-chief of Aerosol Science and Technology. His research spans the field of aerosol science, including atmospheric aerosols, aerosol instrumentaton, aerosol synthesis of nanoparticles and other materials, and bioaerosols. His many contributions to the field of aerosol science have been acknowledged with the Sinclair Award of the AAAR and the Fuchs Award.

2. 6. METHODS FOR THE SEMI-CONTINUOUS MEASUREMENT OF PARTICLE AND GAS CHEMICAL COMPOSITION

   Rodney J. Weber, School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA

   Abstract: A wide variety non-mass spectrometer based methods have been developed recently for automated on-line measurements of particle chemical composition in real, or near real-time. Many of these techniques collect ambient particles in a manner that permits them to be directly coupled to existing analytical devices. Although these approaches generally only provide measurements of bulk chemical composition, they often have unique advantages. Some are highly quantitative and are capable of measuring a wide range of chemical compounds, including gas phase species. Others are relatively low in cost and/or can operate unattended for extended periods making them suitable for network monitoring sites. A review attempting to convey the breadth of these types of approaches will be presented. This will include approaches that convert particles to gases for analysis and liquid-based systems. Methods for measuring a wide range of compounds will be discussed, including inorganic ions, total organic mass and water-soluble organic mass, organic acids, reactive oxygen species (ROS), and specific water-soluble metals. Consideration will be given to the application of newer analytical devices, such as microchip electrophoresis, ion selective electrodes, and liquid waveguide capillary cells with spectroscopic detection. The goal will be to provide resource information and insights into the many research opportunities afforded by these types of systems.

   Rodney J. Weber is a professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology. He received a bachelor's degree in mechanical engineering from the University of Waterloo and masters and doctorate degrees in mechanical engineering from the University of Minnesota.

3. 7. AEROSOL THERMODYNAMICS

   Athanasios Nenes, Schools of Earth and Atmospheric Sciences and Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA

   Abstract: The equilibrium thermodynamic properties of the mixture of acids, salts, and organic compounds present in the atmosphere largely control gas/aerosol equilibrium and the water uptake of soluble aerosol components in response to temperature and relative humidity changes. This course will cover the following fundamentals: the water uptake of different soluble components of aerosols, including organic compounds; the precipitation of solid phases and metastable equilibria; the Phase Rule; Henry's law; the Kelvin effect; and activity coefficients and deviations from ideal solution behavior. There will be some discussion of predictive methods for thermodynamic properties (notably vapor pressures) of atmospheric organic compounds, activity coefficient models for the liquid phase, and the types and sources of data that can be used in these models.

   Athanasios Nenes is an associate professor in the Schools of Earth and Atmospheric Sciences and Chemical and Biomolecular Engineering at the Georgia Institute of Technology. He received a diploma in chemical engineering from the National Technical University of Athens, a masters degree in atmospheric chemistry from the Rosenstiel School of Marine and Atmospheric Sciences, and a doctorate in chemical engineering from the California Institute of Technology. He is the developer of the ISORROPIA aerosol thermodynamic model and co-inventor of the Continuous Flow Streamwise Thermal Gradient CCN Chamber. He has received the Friedlander Award of the AAAR and the Henry G. Houghton Award Award of the AMS.

4. 8. NEW PARTICLE FORMATION IN THE ATMOSPHERE

   Peter H. McMurry, Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN

   Abstract: New particle formation (NPF) contributes to concentrations of atmospheric Atiken and cloud condensation nuclei (CCN). Because NPF affects CCN concentrations, it likely affects the extent of cloud cover and the optical properties of clouds. Thus, NPF is a process that is both scientifically interesting and important for climate modeling. This tutorial will provide an overview of what is known and what is not yet understood about NPF. The tutorial will show that the impact of NPF is determined both by the formation rate of stable nuclei (i.e., the nucleation rate), and the subsequent growth rates of those freshly nucleated particles. Both nucleation rates and growth rates are significantly higher than were predicted by early naïve models, and research is underway to understand why. The tutorial will conclude with a summary of measurement methods that have been developed to understand these processes.

   Peter H. McMurry completed his PhD at Caltech in 1977 and has been on the faculty of the University Minnesota Department of Mechanical Engineering since then. His research focuses on aerosol measurement and behavior with a primary focus on atmospheric aerosols. His current research in this area focuses on new particle formation and in situ methods for measuring physical and chemical properties of complex particles. Measurement techniques that his group has developed include methods to detect and size particles down to 1 nm, aerodynamic lenses, and various tandem measurement methods for studying aerosol properties and processing. He received the Fuchs Memorial Award (2006) and a Guggenheim Fellowship (2007-2008). He became editor-in-chief of Aerosol Science and Technology in May 2008.

Third Session: 1:00 p.m. - 2:40 p.m.

1. 9. CHEMICAL TRANSPORT MODELING OF AEROSOLS

   Peter J. Adams, Department of Civil and Environmental Engineering and the Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA

   Abstract: Chemical transport models (CTMs) are numerical simulations representing the interplay of emissions, chemistry, transport, microphysics, and deposition that determines the behavior of atmospheric aerosols. As research tools, they play several important roles: assessing the significance of newly discovered or hypothesized processes in an atmospheric context, testing our knowledge of aerosol behavior against ambient observations, and predicting the impacts of policy decisions. Conceptually, they are simple mass and population balances. Complexity arises from several factors: the chemical and physical interactions of many dozen species; transport across a three dimensional grid representing an urban airshed, a geographic region or even the entire globe; and the numerical approximations required to solve the resulting equations efficiently. This tutorial will provide an overview of the essential components of CTMs, surveying the major algorithms for representing aerosol emissions, chemistry, microphysics, phase partitioning, transport, and deposition. Special focus will be paid to numerical algorithms for representing aerosol size distributions and their evolution via the microphysical processes of condensation, coagulation, and nucleation.

   Peter J. Adams is an associate professor at Carnegie Mellon University with a joint appointment between the Department of Civil and Environmental Engineering and the Department of Engineering and Public Policy. He earned his bachelor's degree in chemical engineering from Cornell University in 1996, followed by a masters and then PhD in chemical engineering at the California Institute of Technology in 1998 and 2001 respectively. His research interests include aerosol-climate interactions, global and regional aerosol modeling and the development of aerosol microphysical simulations in climate models. Dr. Adams received the Sheldon K. Friedlander Award in 2004 from AAAR.

2. 10. INTRODUCTION AND USE OF WEB-BASED RESOURCES FOR AEROSOL CALCULATIONS

   Scot T. Martin, School of Engineering and Applied Sciences and the Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA

   Abstract: This tutorial will introduce basic aerosol concepts along with computational tools for their practical implementation. The translation of the equations and the knowledge in the seminal papers and books underlying the foundations of aerosol science and technology can in theory be implemented from many widely available source codes, but in practice there is a nontrivial activation barrier for new students to translate source code to application. Web-based interfaces are one emerging solution. The focus of the tutorial is on practical tools for aerosol calculations related to topics including: size distributions, particle charging, types of diameters (i.e., volume-equivalent, mobility, aerodynamic, vacuum aerodynamic, and so forth), deliquescence, efflorescence, hygroscopic growth, mobility filtering with a differential mobility analyzer (DMA) (including several levels of transfer functions), CCN activation, and optical properties. The underlying physical equations used in the algorithms will also be presented, with clear attributions to original sources. The intention is that graduates of this tutorial will be primed for practical, advanced applications (i.e., theory and practice with the balance toward practice) concerning the covered topics.

   Scot T. Martin is the Gordon McKay Professor of environmental chemistry in the School of Engineering and Applied Sciences and in the Department of Earth and Planetary Sciences at Harvard University. His educational background includes an undergraduate degree in chemistry from Georgetown University, a graduate degree in chemistry from the California Institute of Technology, and postdoctoral experience at the Massachusetts Institute of Technology.

3. 11. ICE NUCLEATION BY ATMOSPHERIC AEROSOLS

   Paul J. DeMott, Department of Atmospheric Science, Colorado State University, Fort Collins, CO

   Abstract: Understanding and predicting initiation of ice in clouds and its potential relation to the changing state of atmospheric composition remain as enigmatic topics. Yet such knowledge and capabilities are critical to ultimately understanding and quantifying the role of aerosols and clouds in affecting weather and climate. This tutorial will review present understanding of ice formation by atmospheric aerosols. As a first-time tutorial, the scope will be broad. Emphasis will be on techniques for measuring ice nuclei but will include current understanding of ice nuclei sources and how ice nucleation processes are conceptualized (mechanisms), treated theoretically, and parameterized. Some requirements for and examples of direct comparisons of ice nuclei and cloud ice number concentrations will be described. Finally, future challenges for ground-based and aircraft measurements, theory, and modeling will be discussed.

   Paul J. DeMott is a senior research scientist in the Department of Atmospheric Science at Colorado State University. He received his BS degree in atmospheric sciences at the State University of New York University at Albany and his MS and PhD degrees in atmospheric science from Colorado State University. He directed development of expansion cloud chamber facilities and helped in constructing the first airborne continuous flow diffusion chamber for atmospheric measurements of ice nucleating aerosols.

4. 12. NUMERICAL MODELING OF MULTIPHASE FLOWS

   Sean C. Garrick, Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN

   Abstract: This tutorial presents the state-of-the-art in modeling and simulation of multi-phase flows. The models, tools and techniques presented will highlight and delve into both scientific investigation and engineering practice. Specific attention will be given to the need for turbulence models, the coupling of Eulerian and Lagrangian dynamics, and spanning the wide range of length and time scales present in variety of multi-phase flows. Additionally, the inter-relatedness of computational and experimental/physical investigation in the dynamics and chemistry of aerosols, and how they may better inform each other will be presented.

   Sean C. Garrick is an associate professor of mechanical engineering at the University of Minnesota. His research group investigates nanoparticle formation and growth and turbulent reacting multiphase flows. They also develop models for the effects of turbulence on chemical reactions, nanoparticle nucleation, and particle coagulation. Dr. Garrick earned his PhD in mechanical engineering from the State University of New York at Buffalo in 1998.

Fourth Session: 3:00 p.m. - 4:30 p.m.

1. 13. AEROSOL DRY DEPOSITION FROM THE AMBIENT ATMOSPHERE

   Cliff I. Davidson, Departments of Civil and Environmental Engineering/Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA

   Abstract: Dry deposition is one of the key removal processes for atmospheric aerosols, along with wet deposition and capture of aerosols by fog and cloud droplets. Yet it is challenging to model or measure dry deposition, mainly because any modeling technique must greatly simplify the interactions between particles and atmospheric air motions, and any measurement method is likely to interfere with the natural deposition process. This tutorial will first explore the physics of dry deposition and examine some of the mathematical relationships developed to explain the various deposition mechanisms. Attendees will then consider several measurement methods for dry deposition, including both airborne sampling and surface flux techniques. Finally Dr. Davidson summarize some of the available modeling and measurement data from the literature and point out strengths and weaknesses in our understanding.

   Cliff I. Davidson is a professor in the Department of Civil and Environmental Engineering and the Department of Engineering and Public Policy at Carnegie Mellon University. He is the founding director of the Center for Sustainable Engineering at that university. He received his BS degree in electrical engineering from Carnegie Mellon and MS and PhD degrees in environmental engineering science from the California Institute of Technology.

2. 14. THE EFFECT OF OCEAN BIOGEOCHEMISTRY ON AEROSOL, CLOUDS AND CLIMATE

   Nicholas Meskhidze, Department of Marine Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC

   Abstract: Biogeochemical coupling between the surface ocean and lower atmosphere is poorly quantified but of fundamental importance to understanding the climate system. The science issues discussed will include: 1) atmospheric aerosol deposition as a control on oceanic nutrient distributions and biological productivity, 2) biogenic gas emissions from the ocean and their impact on atmospheric photochemistry, aerosol/cloud interaction and radiative properties of the overlying atmosphere, 3) the physical production of aerosols at the sea surface, and the chemical and radiative properties of those aerosols. This tutorial will present process-level understanding of biogeochemical ocean/atmosphere interaction, and provide an overview of different model parameterizations capable of simulating them.

   Nicholas Meskhidze is an assistant professor in the Department of Marine Earth and Atmospheric Sciences, North Carolina State University. His educational background includes a diploma in physics from Tbilisi State University, a masters degree in environmental management from International Center for the Environmental Management and Planning, a doctorate in atmospheric chemistry from Georgia Institute of Technology, and postdoctoral experience at Georgia Institute of Technology.

3. 15. MORE THAN THE SUM OF THE PARTS: SATELLITE AEROSOL REMOTE SENSING, AND ITS RELATIONSHIP TO SUB-ORBITAL MEASUREMENTS AND MODELS

   Ralph A. Kahn, NASA Goddard Space Flight Center, Greenbelt, MD

   Abstract: Space-borne instruments are providing increasing amounts of data relating to global aerosol spectral optical depth, horizontal and vertical distribution, and very loose, but spatially and temporally extensive, constraints on particle micro-physical properties. The data sets, and many of the underlying techniques, are evolving rapidly. They represent a vast amount of information, potentially useful to the AAAR community. However, there are also issues, some quite subtle, that scientific users must take into consideration. This tutorial will provide one view of the answers to the following four questions:

   1. 1) What satellite-derived aerosol products are available?
   2. 2) What are their strengths and limitations?
   3. 3) How are they being used now?
   4. 4) How might they be used in conjunction with each other, with sub-orbital measurements, and with models to address cutting-edge aerosol questions?

   Ralph A. Kahn is a senior research scientist in the Laboratory for Atmospheres at GSFC. He is the aerosol scientist for the Multi-angle Imaging SpectroRadiometer (MISR) instrument which flies aboard the NASA Earth Observing System's Terra satellite. Dr. Kahn received his PhD in applied physics from Harvard University.

4. 16. SOURCE APPORTIONMENT/SOURCE CHARACTERIZATION TECHNIQUES

   Mike P. Hannigan, Department of Mechanical Engineering, University of Colorado, Boulder, CO

   Abstract: Source apportionment via receptor modeling can be as simple as (1) quantifying cholesterol in the smoke from your grill, (2) in the aerosol in a sample from your city, and (3) using the ratio to determine the amount of hamburger cooking in the city. In general, receptor modeling involves accounting for the mass measured at a receptor site. There is a broad range of accounting approaches used ranging from the simple tracer approach highlighted above to a full Chemical Mass Balance (CMB) modeling to Principle Component Analysis (PCA) to Positive Matrix Factorization (PMF). During this tutorial the participants will learn the strengths and weaknesses of each accounting approach through hands-on modeling activities. Interested attendees are encouraged to bring their laptops so they can play with some real world aerosol measurement data. This course will present the underlying chemical basis for distinct profiles for different types of emission sources and how these differences in profiles then provide a basis for receptor models. The conceptual framework of receptor models, a mass balance approach, will be described and how resulting models can be implemented depending on what a priori information is available. Applications of several types of models to various problems will be described with an emphasis on the practical use of positive matrix factorization for both elemental and organic species data.

   Mike P. Hannigan is an assistant professor in the Department of Mechanical Engineering at the University of Colorado. He received a BS in civil engineering from Southern Methodist University in Dallas and both MS and PhD in environmental engineering science from the California Institute of Technology.