Background image: High resolution sky and cloud photograph looking vertically upward, at Department of Energy Atmospheric Radiation Measurement site in north central Oklahoma, July 31, 2015, 1635 UTC (local sun time = UTC - 6.5 h; 16:35 = 10:05 sun time). See High-Resolution Photography of Clouds from the Surface: Retrieval of Optical Depth of Thin Clouds down to Centimeter Scales.
Publications and Presentations
Recent Popular Lectures
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Education and Honors
Complete Publications, PDF format
Curriculum Vitae, PDF format
Senior Scientist, 1990-
Chief Scientist, Atmospheric Science Program, U.S. Department of Energy, 2004-2009.
Adjunct Professor (Institute for Terrestrial and Planetary Atmospheres), 1994-97
Earth energy budget and climate change: Relating global temperature change, forcing, and climate sensitivity, mainly through observations. A major puzzle is why Earth's temperature has not increased as much as expected from the forcing by the increased loading of atmospheric greenhouse gases. Depending on the magnitude of offsetting forcing by anthropogenic tropospheric aerosols this could imply either a lower climate sensitivty than generally assumed (low aerosol forcing) or a commitment to much greater increase in global temperature than has been observed already. To my thinking quantitative resolution of this question is the key issue facing the climate change research community, with major societal implications.
Cloud optical depth and structure at centimeter scales: High-resolution digital photography such as the background image on this web page permits detailed examination of cloud structure. See High-Resolution Photography of Clouds from the Surface: Retrieval of Optical Depth of Thin Clouds down to Centimeter Scales.
Role of tropospheric aerosols as shortwave forcing agents: Anthropogenic aerosols, derived mainly from combustion-related processes, influence Earth's climate by scattering solar radiation and by modifying the properties of clouds, enhancing their albedo (reflectance) and lifetimes against precipitation formation, both of which effects decrease absorption of solar radiation by the planet and thus exert a cooling effect on climate. Our 1992 paper in Science, which provided initial global estimates of this forcing effect by anthropogenic sulfate aerosols, has been enormously influential with over 3000 citations to date.
Sea spray aerosols: Sea spray aerosols are one of the most important aerosols globally and especially in the marine atmosphere, where they exert a major influence on clouds. Consequently these aerosols must be accurately represented in chemical transport models and climate models. Our monograph Sea Salt Aerosol Production: Mechanisms, Methods, Measurements, and Models -- A Critical Review published in 2004 by the American Geophysical Union presents the pertinent chemistry and physics of sea spray aerosol production and the atmospheric dynamics of these particles as well as summarizing pertinent field measurements and laboratory experiments.
Atmospheric radiation: Instrumental in establishment of Department of Energy Atmospheric Radiation Measurement Program. Paper describing this program in the Bulletin of the American Meteorological Society (1994) has over 700 citations.
Cloud chemistry and acid deposition: Demonstrated importance of oxidation by H2O2 in converting SO2 to sulfuric acid deposited in rain through laboratory studies, field measurements, and chemical transport modeling. Demonstrated rapid and highly efficient scavenging of aerosol particles into cloud water. Demonstrated lack of reaction of NO2 in liquid water clouds, contrary to widespread prior understanding. Science paper (1989) was influential on 1992 Acid Deposition amendments to Clean Air Act.
Physical chemistry: Laboratory and theoretical studies of gas- and aqueous-phase kinetics. Delineated roles of mass transport processes in controlling reactions in cloudwater, stimulating much research nationally and internationally. The 1986 paper "Mass-transport considerations pertinent to aqueous phase reactions of gases in liquid-water clouds" has over 500 citations.
Books: Authored, 1; edited, 2
National and international reviews, 11
Journal articles and book chapters, 135
Proceedings and abstracts, 240
Reports and reviews, 40
Complete Publication list, PDF format
NSF Graduate Fellow 1963-67
Woodrow Wilson Fellow (Hon.) 1963-64
Ramsay Memorial Fellow, 1968-69
Priestley Lecture. Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Bureau of Meteorology (BoM), Melbourne, Australia, 2011.
Plenary Lecture, Korean Meteorological Society, Autumn Meeting, Daejon, Korea, 2008.
Plenary Lecture, International Workshop on Integrated Responses to Climate Change, Seoul, Korea, 2008.
ISI Highly Cited Researcher, Thompson Scientific, 2006.
Science and Technology Award, Brookhaven National Laboratory, 2006.
Fellow, American Geophysical Union, 2005.
Haagen-Smit Award for an "Outstanding paper" published in Atmospheric Environment, 2003. Citation. BNL News Release.
Fellow, American Association for the Advancement of Science, 2002. BNL News Release.
Plenary Lecture, 16th International Conference on Nucleation and Atmospheric Aerosols, Kyoto, 2004.
Plenary Lecture, 16th Annual Meeting, American Association for Aerosol Research, Denver, 1997.
Plenary Lecture, 14th International Conference on Nucleation and Atmospheric Aerosols, Helsinki, 1996.
Editor's Citation for Excellence in Refereeing, Journal of Geophysical Research - Atmospheres, 1995, 2002.
Sigma Xi, 1969 (University of California, Berkeley).
Phi Beta Kappa, 1963 (Harvard College).
Lead Scientist, Tropospheric Aerosol Program, U. S. Department of Energy, 2000-2004.
Science Board, (Department of Energy Atmospheric Radiation Measurement Program) Climate Research Facility, 2004-2006.
Scientific Steering Committee, National Aerosol-Climate Interactions Program, 2001.
Management Team, Atmospheric Radiation Measurement (ARM) Program, Department of Energy, 1990-99.
Steering Committee, ACE-2 (Aerosol Characterization Experiment: Radiative Forcing due to Aerosols over the Polluted North Atlantic Region), 1993-97.
American Association for Aerosol Research
American Chemical Society and its Divisions of Physical Chemistry and Environmental Chemistry
American Geophysical Union (Fellow)
American Meteorological Society
American Physical Society
Geselschaft für Aerosolforschung
International Union for Pure and Applied Chemistry (Fellow)
Contributing Author, "Couplings Between Changes in the Climate System and Biogeochemistry" In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.
Contributing Author, "Aerosols, their Direct and Indirect Effects" and "Radiative Forcing of Climate Change" in Climate Change 2001 - The Scientific Basis, Intergovernmental Panel on Climate Change.
Co-Chair, Fourth Santa Fe Conference on Global & Regional Climate Change, Santa Fe, NM, February 5-10, 2017.
Atmospheric Sciences Section Fellows Committee, American Geophysical Union, 2017-
Clean Air Scientific Advisory Committee (CASAC) Secondary National Ambient Air Quality Standards Review Panel for Oxides of Nitrogen and Sulfur, U.S. Environmental Protection Agency, 2015-
Co-Convener, Symposium on Physical and Atmospheric Chemistry in Honor of Harold Johnston, American Chemical Society, Division of Physical Chemistry, San Francisco CA, 2000.
President, Brookhaven Organization of Scientists, 1997-99.
Committee on Global Environmental Change, 1994-98, and Climate Change Panel, American Geophysical Union, 1998. This committee and panel drafted the 1998 AGU Position Statement on Climate Change and Greenhouse Gases. Eos 80 (5), 49, 1999. For reaction to this statement, including a statement by then Vice President Gore, click here.
Advisory Board, Tellus B, 1997-2003.
Spotlight Lecture, Colby College, Waterville, ME, 1996.
North American Editor/Chemistry and Editorial Advisory Board, Urban Atmosphere, 1991-95.
Co-chair, Gordon Research Conference, Atmospheric Chemistry, Newport RI, 1995.
Invited witness, Aerosols and Climate, Hearing on the Science Concerning Global Climate Change, Committee on Energy and Natural Resources, U. S. Senate, Washington, DC, 1994.
Panel on Atmospheric Effects of Stratospheric Aircraft, National Research Council, 1993.
Editorial Advisory Board, International Journal of Chemical Kinetics, 1993-95.
Invited participant, Mission to Washington--Joint Appeal by Religion and Science for the Environment, U. S. Senate, Washington DC, 1992.
Contributing Author, 1992 IPCC Supplement, Intergovernmental Panel on Climate Change, 1992.
International Union of Pure and Applied Chemistry, Commission on Atmospheric Chemistry, Associate Member, 1991-94; Titular Member, 1995-98 ; Interdivisional Committee on Nomenclature and Symbols, International Union of Pure and Applied Chemistry, Titular Member, 1998- .
Co-chair, Fifth International Conference on Precipitation Scavenging and Atmosphere-Surface Exchange Processes, Richland WA, 1991, and Coordinator (with W. G. N. Slinn) of proceedings, published as Precipitation Scavenging and Atmosphere-Surface Exchange, (Hemisphere, Washington DC, 1992).
Primary Co-author, "Atmospheric Process Research and Development", Report 2 of Acidic Deposition: State of Science and Technology, U. S. National Acid Precipitation Assessment Program, Washington DC, 1991.
Committee on Atmospheric Chemistry, National Research Council, 1988-91.
Associate Editor, Journal of Geophysical Research - Atmospheres, 1986-89.
Committee on Atmospheric Chemistry, American Meteorological Society, 1985-91. This committee drafted the 1998 AMS Position Statement on Acid Deposition, Bull. Amer. Meteorol. Soc. 70, 1039-1040, 1989.
Associate Editor, Atmospheric Environment, 1984-95. Editor, Trace Atmospheric Constituents, Advances in Environmental Science and Technology, Vol. 12 (John Wiley and Sons, New York, 1983).