Tropospheric aerosols

Understanding the factors involved in seasonal and interannual variations in aerosol concentrations measured at receptor sites after long range transport is complicated by the relatively short lifetimes of aerosols, compared with many greenhouse gases. We are currently involved in two projects that make use of field observations to shed light on aerosol sources and transport.


Our study of trans-Pacific transport makes use of a unique, 20-year data set of aerosol ionic composition, obtained by the University of Hawaii at Manoa, and analysis of atmospheric transport patterns to evaluate the causes of variability of aerosol concentrations observed at Mauna Loa Observatory.


As part of the 7SEAS study, and together with a number of collaborators, we are making measurements of aerosol properties in Singapore and in the South China Sea. These observations will be used to achieve a better understanding of how the complex and numerous natural and anthropogenic aerosol sources in the region interact with each other, and with the meteorology of the region.


Smoke emissions and chemistry

Particulate matter (PM) represents <~1% of the mass emitted by biomass combustion but has large effects on visibility, climate, and human health. In a series of studies over the past decade, we have conducted laboratory studies of the emissions from open burning of biomass, and characterized the aerosol chemical, optical and cloud-nucleating properties. In more recent studies we have investigated the gas-aerosol partitioning of emitted organic species, and have also participated in an airborne campaign sampling prescribed fires in South Carolina.


More information about the FLAME I and II studies

More information about the FLAME III study (Fall 2009)

More information about the FLAME IV study (Fall 2012)

The SCREAM study

Aerosols, clouds and climate

Atmospheric particles capable of nucleating cloud drops and/or ice crystals in the atmosphere play key roles in precipitation formation and cloud-climate interactions. Our group conducts lab and field studies of ice nuclei (IN) and cloud condensation nuclei (CCN), and has developed parameterizations for representing IN and CCN in large scale models. The BEACHON study is a multidisciplinary effort to evaluate atmosphere-biosphere interactions and feedbacks, particularly those involving biogenic aerosols.


We are also undertaking modeling studies of Arctic mixed-phase clouds in order to understand how IN affect cloud phase and lifetime. Our goal is to develop a simplified treatment to link ice nucleation to observed aerosol properties, that can be used in global climate modeling. This work is supported under the Center for Multiscale Modeling of Atmospheric Processes (CMMAP), a National Science Foundation Science and Technology Center housed at Colorado State University, focused on improving the representation of cloud processes in climate models.


More information about CSU ice nucleation research

More information about the BEACHON study

More information about Arctic cloud modeling

Visibility and Deposition

Over the past two decades, we have conducted a number of studies in national parks and wilderness areas, aimed at developing a better understanding of the aerosol properties, and their sources, that affect visibility. Previous studies in Great Smoky Mountains, Big Bend National Park, the Grand Canyon, and Yosemite National Park have focused on characterizing the regional aerosol and how aerosol size distributions and chemical composition affect light extinction. Our current study applies aerosol optics in a different way: to examine the impacts of particulate matter on light pollution impacting national parks.


Most recently, we have supported field studies examining nitrogen deposition to Rocky Mountain and Grand Teton National Parks, where recent trends suggest that negative impacts on ecosystems may be imminent. The sources and the speciation of nitrogen inputs to these regions are not yet well understood.


More information about the Night Sky Project

More information about the RoMANS study

More information about the GrandTReNDS study