Kimberly Prather

Kimberly Prather is an American scientist who is an Atmospheric Chemist, Distinguished Chair in Atmospheric Chemistry, and a Distinguished Professor at the Scripps Institution of Oceanography and Department of Chemistry and Biochemistry at UC San Diego. Her work focuses on how humans are influencing the atmosphere and climate. In 2019, she was elected as a member of the National Academy of Engineering. She is an elected Fellow of the American Geophysical Union, the American Association for the Advancement of Science, and the American Academy of Arts and Sciences.

Prather was born in Santa Rosa, California. She studied at Santa Rosa Junior College and University of California, Davis, earning a Bachelor's degree in 1985 and a PhD in 1990. She served as a postdoctoral fellow at the University of California, Berkeley between 1990 and 1992, working with Nobel Laureate Yuan T. Lee. Prather joined University of California, Riverside as an Assistant Professor in 1992. During her time at UC Riverside she began to work on aerosol mass spectrometry, developing ways to make it compact and transportable. She patented the technology.

In 2001, Prather joined the faculty at the University of California, San Diego as a member of the Dept. of Chemistry and Biochemistry and Scripps Institution of Oceanography. Prather's early research focused on determining the major sources of fine particle pollution in California as well as in the Northeastern United States. As part of this research, she explored methods to distinguish between different aerosol sources based on their single particle composition and size. She developed aerosol time-of-flight mass spectrometry (ATOFMS), a technique with high temporal and size resolution. In 1999 she began to work with the University of Rochester studying the health effects of ultrafine particles. She refined the detection technique so that it would precisely measure the size and composition of small particles. The ultrafine ATOFMS was able to examine exhaust particles from gasoline and diesel powered vehicles. She found that alongside the freeway, particles between 50 and 300 nm were mainly due to heavy-duty vehicles (51 %) and light-duty vehicles (32 %). She used the ultrafine ATOFMS to study atmospheric composition, combining it with ozone and NOx measurements. ATOFMS is now widely used in atmospheric studies around the world.

In 2003, she joined the advisory board of United States Environmental Protection Agency PM2.5 Clean Air. Between 2003 and 2006 Prather studied whether ATOFMS could be used to measure the carbonaceous components of aerosols (including PAHs) and help to understand atmospheric processes, distinguishing between organic (OC) and elemental carbon (EC). Prather showed it was possible to distinguish EC and OC on a single particle level, and investigated their chemical associations with ammonium, nitrate, and sulfate. Her group explored ways to calibrate the ATOFMS data, making real-time apportionment of ambient particles possible. They did this by classifying particles using an artificial neural network (ART-2a). In 2008 she joined CalWater; a multi-year interdisciplinary research effort that looked to study the water supply in the West Coast of the United States. Her PhD student Kerri Pratt led the Ice in Clouds Experiment - Layer Clouds (ICE-L) study. ICE-L included the first aircraft ATOFMS, named Shirley. Pratt and Prather studied ice crystals in situ on high speed aircraft flying above Wyoming, and found that the particles were mainly composed of dust or biological particles (bacteria, fungal spores or plants). Understanding these composition of airborne particles is imperative to properly evaluate the impact of climate change, as well as providing insight into cloud formation.

In 2010 she became the founding Director of the NSF Center for Aerosol Impacts on Climate and the Environment (CAICE). The CAICE was made a National Science Foundation Phase II Center for Chemical Innovation in 2013. In this role, Prather develops new analytical techniques for aerosol chemistry. Her group demonstrated that dust and aerosols in the Sahara can influence precipitation in Western United States.Prather studied the microbes that rise from the ocean, become airborne and contribute to the global temperature. The experiment was conducted by storing thousands of gallons of water from the Pacific Ocean, provoking wind and waves and encouraging the growth of organisms. As part of CAICE, her group was the first to identify the major factors controlling chemical composition of sea spray, finding that the characteristics depended on the physical forces and ocean biology of the waves. They demonstrated two types of droplets; "film" drops that were full of microbes and organic materials, and "jet" drops that mainly contained sea salt and other biological species. Prather's research team can explore the impact of carbon dioxide on the global temperature by controlling the amount entering their ocean simulation chamber. The Scripps Ocean Atmosphere Research Simulator (SOARS) will open in 2020 and allow the study of how wind, temperature, sunlight and pollution impact the ocean. The funding was extended by the National Science Foundation in 2018, with a second $20 million grant allowing them to investigate the interaction of human pollution with ocean-produced gases and aerosols.

• 1994 American Society for Mass Spectrometry Research Award
• 1994 National Science Foundation Young Investigator
• 1997 National Science Foundation Special Creativity Award
• 1998 Gesellschaft für Aerosolforschung Smoluchowski Award
• 1999 American Association for Aerosol Research Kenneth T. Whitby Award
• 2000 ACS Analytical Chemistry Arthur F. Findeis Award
• 2009 UCSD Faculty Sustainability Award
• 2009 American Association for the Advancement of Science Fellow2010 American Geophysical Union Fellow
• 2010 American Academy of Arts and Sciences Fellow
• 2010 ACS Creative Advances in Environmental Science and Technology
• 2011 ACS San Diego Distinguished Scientist Award
• 2015 California Air Resources Board Haagen-Smit Clean Air Award
• 2018UC San Diego Chancellor’s Associates Excellence Award in Research in Science and Engineering
• 2019 Elected to the National Academy of Engineering