Cooperative Institute for Research in Environmental Sciences

Jose-Luis Jimenez

Research Interests

The Jimenez group’s research centers on the development and application of advanced instrumentation for real-time, quantitative measurements of the size, chemical composition, and morphology of submicron aerosols. We care about atmospheric aerosols for many reasons, including their effect on radiation balance (climate forcing), severe short-term and long-term effects on human health, reduced visibility, and acid deposition ("acid rain"). Most of these effects are not well understood, in good part due to the limitations of the instrumentation available. Advanced instrumentation can be used to make much faster progress in many of these areas. Aerosols are also important for other applications such as nanomaterials fabrication and pharmaceutical drug delivery.

Current Research Highlight: Evolution of Organic Aerosols in the Atmosphere

Organic compounds compose a major fraction of airborne particles. These particles influence cloud formation and therefore radiation balance and rainfall. They also affect human health and can lead to illnesses such as asthma, heart disease, and lung cancer. But so far only about 10-30 percent of the thousands of individual compounds have been identified, and past research has focused on following specific molecules with the idea that these compounds remain relatively static in nature once they enter the atmosphere. Recent discoveries by our research group and colleagues show that the life cycle of these compounds is much more complex, with organic molecules reacting many times over in many different ways. Attempts by atmospheric scientists to track this life cycle often leave researchers with a sea of divergent paths to follow.

To find some order in this chaos, we began looking at organic aerosols (OA) with a more holistic mindset. Through a series of field observations and lab experiments from all over the world, we found that organic matter ultimately tends to evolve towards a similar end, regardless of the source or where they occur in the atmosphere. In a paper in the journal Science (Jimenez et al. 2009), we presented a unifying model framework describing the atmospheric evolution of OA, which is constrained by high-time-resolution measurements of their composition, volatility, and oxidation state. OA and OA-precursor gases evolve by becoming increasingly oxidized, less volatile, and more hygroscopic, leading to the formation of oxygenated organic aerosol (OOA) mass with concentrations comparable to sulfate aerosol throughout the Northern Hemisphere. The complex evolution of OA contrasts with the simpler behavior of sulfate, which is irreversibly oxidized and condensed. Current modeling frameworks for OA are constructed in analogous way to those for sulfate, with either no aging or one-step oxidation. This paper presented a unifying framework describing the atmospheric evolution of OA, which is directly connected to worldwide observations and experimentally verifiable, and can be used to evaluate and form the basis of practical, phenomenological modeling approaches. The combination of measurements and the modeling framework imply that most OA is an intermediate state of organic material, between primary emissions of reduced species and highly oxidized volatile products (CO and CO₂). Future models, inventories, and measurements will almost certainly need to account for the dynamic sources and sinks of OA to accurately predict regional and global OA distributions and properties, and thus the associated health and climate effects.

Caption: Total mass concentration (μg/m3) and mass fractions of non-refractory inorganic species and organic components in submicron aerosols measured at multiple surface locations in the Northern Hemisphere. The organic components were obtained from factor analysis of aerosol mass spectrometry data (FA-AMS). For some studies the FA-AMS methods identified one oxygenated organic aerosol (OOA) factor, while in other locations two types, semivolatile (SV) and low-volatility (LV) OOA, were identified. HOA stands for hydrocarbon-like OA, a surrogate for urban primary OA, while “Other OA” comprises primary OAs other than HOA that have been identified in several studies, including biomass-burning OA (BBOA). Click here for a high-resolution image.

Publications

Complete List of Publications

Honors and Awards

• 7th Most Cited Scientist in the Geosciences Link
• 2012 AGU Ascent Award "as an exceptional mid-career scientist demonstrating excellence in research and leardership in his field"
• Citation Index h = 60 (from ISI Web of Science, 12,658 citations) (Researcher ID Link)
• 2010 "Rosenstiel Award" of the Rosenstiel Foundation and the Rosenstiel School of Marine and Atmospheric Science at the University of Miami for "outstanding contributions" and a "significant and growing impact in the last decade" in marine and atmospheric science.
• Kenneth T. Whitby Award of the American Association for Aerosol Research (AAAR), 2008
• 2007 Provost Faculty Achievement Award, CU-Boulder
• 2004 NSF Young Investigator "CAREER" Award
• Two "Fast Breaking Paper" recognitions from Thomson ISI for Ulbrich et al. (ACP 2009) and Jimenez et al. (Science 2009)
• 73 "Highly Cited Papers" (ISI, Top 1% in their fields) and 2 "Hot Papers" (Top 0.1%)
• 3 "Top 20 Cited Papers" in Environmental Science and Technology
• NASA Group Achievement Awards, 2003, 2006, and 2008
• La Caixa Foundation Doctoral Fellowship, 1994-1996
• Full CV

Professor Jimenez is a member of the CIRES Professor.