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Jeffrey L. Collett, Jr. - Professor and Department Head

Jeffrey L. Collett, Jr.


Career Overview

Professor Jeff Collett received a B.S. in Chemical Engineering from MIT in 1984 and M.S. and Ph.D. degrees in Environmental Engineering from Caltech in 1985 and 1989. Following completion of the Ph.D., he spent two years as a postdoctoral research associate in the Laboratory for Atmospheric Physics at ETH-Zurich and three years as an assistant professor at the University of Illinois holding joint appointments in the Institute for Environmental Studies and the Environmental Engineering Program in the Department of Civil Engineering. He came to Colorado State University in Fall 1994 where he joined the growing Atmospheric Chemistry Program. Dr. Collett was twice named to the Incomplete List of Teachers Rated as Excellent by their Students at the University of Illinois and was named an Office of Naval Research Young Investigator in 1992. His research concerns cloud and precipitation chemistry, the role of clouds as processors of tropospheric particles and trace gases, and the impacts of atmospheric aerosol particles on regional visibility. His interests focus on process-oriented field research, instrument development and environmental chemistry.

Teaching Interests

Research Interests

Dr. Collett's research generally focuses on cloud chemistry, aerosol-cloud-climate interactions, precipitation chemistry and physics, regional air quality, aerosol impacts on visibility, and instrumentation development. Professor Collett's current research is directed toward understanding atmospheric processing of various chemical species and their impacts on pollutant deposition, visibility degradation, and human health.

Ongoing studies of fog chemistry and physics in central California radiation fogs are designed to elucidate the contribution of these widespread valley fogs to particle production and deposition. The research, primarily of an experimental nature, includes both basic, process-oriented studies as well as more applied work directed toward understanding regional air quality issues. Rapid sulfate production in the high pH fogwater found in the region contributes to particle accumulation in winter stagnation episodes, while particle scavenging and deposition via fog drop sedimentation serves as an important vector for particle removal. While past studies have focused on fog processing of inorganic species, it is becoming increasingly apparent that fogs also interact significantly with carbonaceous aerosol particles. Studies are currently underway to optimize techniques for extracting various organic compounds from fog and cloud samples for analysis by GC/MS and other analytical techniques. These techniques are being applied to study fog scavenging of carbonaceous aerosol produced from different combustion source types (e.g., wood smoke vs. motor vehicle exhaust). Dr. Collett is also interested in how chemical heterogeneity among populations of cloud drops influences sulfate production and pollutant scavenging and removal. Several instruments have been designed in the laboratory for sampling cloud and fog drops as a function of drop size in both warm and supercooled clouds. Size-dependent cloud and fog drop compositions have been examined and their impact on aqueous sulfate production rates have been determined. Effects of size-dependent drop composition on pollutant removal, both via sedimentation in radiation fogs and precipitation scavenging in mixed-phase winter clouds, have also been examined. In order to permit sampling of elevated clouds, Dr. Collett has developed an airborne cloud water collector that has flown aboard the NCAR C-130 in studies of marine stratiform clouds.

Another area of current focus is the examination of the chemical and physical properties of aerosol particles in National Parks and other protected visual environments. Recent studies have been conducted in Big Bend National Park, Yosemite National Park, Grand Canyon National Park, Brigantine National Seashore, the San Gorgonio Wilderness Area, and Great Smoky Mountains National Park. Aerosol composition studies include examination of the size-dependent inorganic chemical composition of the aerosol particles as well as semi-continuous measurements of particle composition at 15 minute time resolution. Dr. Collett is examining the organic composition of the particles via GC/MS in order to obtain further clues about the relative importance of various source type contributions and the formation of secondary organic material during aerosol transport to several of these parks. Dr. Collett is also collaborating with colleagues in the CSU Chemistry Department on development of miniaturized, "lab-on-a-chip" systems for measurement of atmospheric pollution. Efforts include work to analyze aerosol ion species, organic acids, and carbohydrates. The goal is to develop small, inexpensive measurement systems for real-time measurement of air pollution levels in a wide range of environments.

Research Sponsors

Awards, Honors, and Positions

Last Updated: 29 June 2012. Contact the Webmaster