The impacts of atmospheric aerosol particles represent the largest uncertainty in scientific understanding of the Earth's climate. The Prather Research Group studies the chemistry of these particles as we look to learn more about their impacts on the planet's energy budget and on the formation of clouds.
The Prather group conducts research focused on improving our understanding of how humans are influencing our atmosphere and climate. In the early part of her career, Prof. Prather and her research group developed a unique method, aerosol time-of-flight mass spectrometry (ATOFMS), for the on-line characterization of the size and chemical composition of atmospheric aerosols. Using ATOFMS and a wide array of other gas and particle instruments, the Prather group is now performing studies worldwide to better understand the role of aerosols in climate change. The ultimate goal of the group's research is to determine which aerosol sources play the largest role in affecting key atmospheric processes, including heterogeneous reactions, cloud formation, and ice nucleation.
The Prather group is aiming to understand the full cycling of atmospheric species as depicted in the figure below. All of these processes are ultimately affected by the chemical composition of individual particles. Traditional chemical analysis methods measure the average composition of an ensemble of particles and thus cannot be used to predict or explain the behavior of individual aerosol particles, as individual aerosol particles have a variety of compositions.
Our relative lack of understanding of aerosol impacts on climate are shown below. The uncertainties related to aerosols are indicated in the top green box. The largest uncertainty in climate change is dependent upon aerosol-cloud interactions-- the ability of aerosols to form clouds. At the center of every cloud droplet, and every ice crystal, is an aerosol particle. Size and chemistry determine whether a particle activates to form a cloud droplet or to form an ice crystal. This group is working to determine which chemical compositions and sources are most effective in seeding clouds and affecting precipitation.
The traditional treatment of aerosols in models is shown in the figure below. ATOFMS results show a picture that differs significantly from this traditional treatment. Ultimately, climate properties are dictated by the combination of chemical species at the individual particle level. ATOFMS data from lab and field studies are currently being used to improve regional and global climate models.
Aerosols offset much of the warming induced by greenhouse gases. In order to develop more effective control strategies, we must develop a much better understanding of how much, and what kinds of, aerosols are offsetting our climate. This is the major goal of this research program.