Special Issue Preface pubs.acs.org/JPCA
Tribute to A. R. Ravishankara overseeing the day-to-day administrative duties of CSD, Ravi also maintains an active role in a number of research activities. Ravi joined NOAA in 1985 as a research chemist and member of the atmospheric chemical kinetics group. Before becoming director of CSD, Ravi was the head of the atmospheric chemical kinetics group, where he developed cutting edge research on gas-phase kinetics and heterogeneous atmospheric chemistry. His research in those years was pivotal in establishing the scientific understanding for processes that impact stratospheric ozone depletion, air quality, and climate change. In 1989 Ravi joined the University of Colorado chemistry department as an adjunct professor, a position that he still holds today. Before moving to NOAA, Ravi spent eight years at Georgia Tech Research Institute (GTRI) in Atlanta, where he rose through the ranks to Principal Research Scientist and Head of the Molecular Sciences Branch. He earned his doctorate in 1975 in physical chemistry from the University of Florida in Gainesville and spent one year as a postdoctoral fellow at the University of Maryland in College Park before accepting his position at GTRI. His masters and bachelor’s degrees were earned at the University of Mysore in Karnataka, India. Ravi has received numerous awards and honors during his career in addition to presenting numerous distinguished lectures. Ravi was elected to the U.S. National Academy of Sciences in 2000. He has received numerous prizes and awards, among them the Presidential Rank Award in 2004 for his work on the ozone layer depletion and contributions to our understanding of climate change and air quality; the American Chemical Society Award for Creative Advances in Environmental Science & Technology in 2005; the U.S. Environmental Protection Agency’s Stratospheric Ozone Protection Award; the U.S. Department of Commerce Silver Medal; and the Royal Society of Chemistry Polanyi Medal in 1998 to name a few. Ravi is an elected fellow to a number of prestigious societies including: the American Geophysical Union (AGU), the International Union of Pure and Applied Chemistry (IUPAC), the Royal Society of Chemistry (RSC), and the American Association for the Advancement of Science (AAAS). A major part of Ravi’s scientific and societal contributions has been his devoted service to the atmospheric chemistry and climate research communities as well as to policy makers. Ravi has taken an active role in bringing the science to the people and making it approachable to society and policy makers. Ravi was a member of the NASA/JPL chemical kinetics and photochemical data evaluation panel for many years (1982− 2007). His invaluable service and contributions to this data assessment over the years directly impacted the development of modern day atmospheric chemistry models and, thus, the atmospheric research community’s ability to more clearly identify key atmospheric chemical processes and needs for further study. Ravi has also served on other scientific evaluation
A. R. Ravishankara (Ravi) has acquired numerous friends and colleagues throughout his prosperous scientific career. It is, therefore, our deepest pleasure and honor to write this tribute. In light of his vast contributions to science, we hope this short tribute echoes not only our own sentiments, but those of his many colleagues that have contributed to this Festschrift issue of the Journal of Physical Chemistry A in honor of A. R. Ravishankara. During his career, Ravi has mentored, hosted, and collaborated with many outstanding scientists, postdoctoral associates, and students from around the globe, as testified by the large extent of his collaborative research. To date, Ravi has coauthored more than 300 peer-reviewed scientific papers. Many of these papers inspired further studies and had seminal impacts on science as well as society. Ravi has also played a pivotal role in numerous atmospheric chemistry and climate assessments as well as being a critical reviewer of scientific studies. These attributes testify to the breadth of his scientific career and its impact. Ravi is currently the director of the Chemical Sciences Division (CSD) of the National Oceanic and Atmospheric Administration (NOAA) Earth Systems Research Laboratory in Boulder, Colorado. Under his leadership, the research performed within CSD aims at discovering, understanding, and quantifying the chemical processes of Earth’s atmosphere while also providing a scientific basis for decisions made in industry and government related to climate change, air quality improvement, and protection of the ozone layer. While © 2012 American Chemical Society
Special Issue: A. R. Ravishankara Festschrift Published: June 21, 2012 5733
dx.doi.org/10.1021/jp304410u | J. Phys. Chem. A 2012, 116, 5733−5734
The Journal of Physical Chemistry A
Special Issue Preface
processes that play a major role in polar ozone chemistry. Some specific examples for such contributions are the measurements of reactive uptake coefficients and mechanisms for the N2O5 + H2O and ClONO2 + H2O reactions on ice and nitric aciddoped ice, as well as the loss of these species on sulfuric acid; reactions that are important for chlorine activation and for removal of the reservoir species during ozone depletion events. Another contribution to heterogeneous processes, in general, and to ozone depletion, in particular, include the introduction of a modeling framework for applying rates of heterogeneous chemical reactions measured in the laboratory to sulfuric acid aerosols that are commonly found in the stratosphere. A conceptual framework of the basic physical and chemical quantities needed to better constrain atmospheric model parameters was developed as part of Ravi’s work. Over the past 20 years or more, the atmospheric lifetimes and fate of greenhouse gases (climate forcing agents) has been a recurring theme in Ravi’s research. Ravi and colleagues have studied the gas-phase and heterogeneous loss processes of key hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs) that have been proposed as commercial replacements for chlorofluorocarbons (CFCs). Comprehensive kinetic studies of the most likely potential atmospheric loss processes of these compounds, e.g. gas-phase reaction with atmospheric oxidants such as OH, O(1D), Cl, NO3, and O3, have been studied using various experimental techniques. As a result, it has been possible to quantify the global warming and ozone depleting potentials of these atmospheric trace gases, which provides the input needed for the scientific assessment of their environmental impacts. It also enables informed decisions to be made regarding their regulation, e.g., the Montreal Protocol, and use. In recent years, Ravi and colleagues have succeeded in obtaining fundamental insights into atmospheric processes through innovative fieldwork. The development of fast and accurate state-of-the-art instrumentation has enabled taking the laboratory directly into the real world. For example, cavity ringdown spectroscopy (CRDS) has been used to directly measure the atmospheric abundance of NO3 and N2O5 providing much needed insight into gas and aerosol phase nighttime atmospheric chemical processes. Coupling the CRDS technique with photoacoustic methods has also been used to examine the optical properties of aerosol (a climate forcing agent) in the laboratory as well as in the field. These few examples highlight Ravi’s fantastic journey that has included delving into various aspects of the chemical processes occurring in the atmosphere, from the boundary layer to the stratosphere, using pioneering laboratory studies and real world state-of-the-art field measurements. Ravi’s research, in many respects, has helped shape the landscape of the field of modern day atmospheric chemical kinetics and atmospheric chemistry on a global scale. Although chapters have been written, Ravi’s anthology of scientific research remains a work in progress. We speak for all of Ravi’s friends and colleagues in wishing him continued success and the best in his future endeavors.
panels and committees such as the National Academy of Sciences Committee on America’s Climate Choices (2008−2010), as cochair of the Scientific Assessment Panel of the Montreal Protocol (2007−present), as cochair of the Stratosphere-troposphere Processes and Their Role in Climate/World Climate Research Programme (SPARC/WCRP) Group on Upper Troposphere/Lower Stratosphere Chemistry (1995−2007), and cochair of the SPARC/IGAC initiative on Laboratory Atmospheric Chemistry (1998−present). His service has covered many important topics of the day that directly (or indirectly) relate to the impact of atmospheric chemistry or chemical processes on our environment and, thus, society. Ravi’s contributions to science, in general, and in particular to the field of atmospheric chemistry and climate change research are not easily summarized in but a few words. A common thread in Ravi’s research goes beyond the specific scientific contributions but carries an intangible element of insight, creativity, and imagination, while crossing interdisciplinary boundaries to unravel key underlying scientific questions. A key element of Ravi’s research is that it strives to provide a basic and fundamental understanding of the critically important atmospheric science issues of our time. Ravi has contributed to many areas under the research umbrella of atmospheric chemistry including chemical kinetics, photochemistry, heterogeneous and multiphase chemistry, aerosol properties, and the measurement of atmospheric constituents. Ravi has been known throughout his career to be more than just a casual colleague or coauthor on a research paper. Ravi brings a wealth of insightful ideas and critical thinking to any research project, while promoting independent thinking. Ravi has and continues to mentor students and young scientists working in the laboratory, but also freely provides input through discussions at meetings, workshops, and symposia held throughout the world. Even for a scientist like Ravi with a large body of high-quality interdisciplinary research to his credit a few research themes are worthy of note. For some, Ravi’s research may be synonymous with laboratory studies of OH radical kinetics, which plays such an important role in the removal (oxidation) of atmospheric trace gases and ozone production. Ravi’s research group developed a robust laser induced fluorescence apparatus for such measurements and applied it to numerous reaction systems relevant to atmospheric chemistry over the years. The work from Ravi’s group, in general, stands out as a result of the thoroughness and care taken while performing measurements under temperature and pressure conditions that are most relevant to atmospheric chemistry. The use of isotopic substitution (OD, 18OH, as well as the use of deuterated reactants) provided insight into reaction mechanisms. Two examples that readily come to mind were studies to determine of the rate coefficients for the reaction of the OH with CH4 (methane) and HNO3 (nitric acid), which are critically important reactions that influence the atmospheric HOx and NOx budgets, while the loss of CH4, an important greenhouse gas, is important on its own. In the early 1980s, the attention of the atmospheric community turned toward the unprecedented springtime loss of stratospheric ozone over the Antarctic, i.e., the Antarctic Ozone hole. Ravi and colleagues at NOAA employed a combination of laboratory experiments, field observations, and modeling studies to help unravel the chemical mechanisms of the underpinning processes leading to the extensive ozone loss observed over the Antarctic. One of the topics that Ravi’s research touched upon was the quantification of heterogeneous
James B. Burkholder NOAA
Yinon Rudich Weizmann Institute
Paul H. Wine Georgia Institute of Technology 5734
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