ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-12-7647-2012 Overview of the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) Zaveri R. A. 1 Shaw W. J. 1 Cziczo D. J. 2 Schmid B. 1 Ferrare R. A. 3 Alexander M. L. 4 Alexandrov M. 5 Alvarez R. J. 6 Arnott W. P. 7 Atkinson D. B. 8 Baidar S. 9 Banta R. M. 6 Barnard J. C. 1 Beranek J. 1 Berg L. K. 1 Brechtel F. 10 Brewer W. A. 6 Cahill J. F. 11 Cairns B. 12 Cappa C. D. 13 Chand D. 1 China S. 14 Comstock J. M. 1 Dubey M. K. 15 Easter R. C. 1 Erickson M. H. 16 Fast J. D. 1 Floerchinger C. 17 Flowers B. A. 15 Fortner E. 18 Gaffney J. S. 19 Gilles M. K. 20 Gorkowski K. 14 Gustafson W. I. 1 Gyawali M. 7 Hair J. 3 Hardesty R. M. 6 Harworth J. W. 8 Herndon S. 18 Hiranuma N. 1 Hostetler C. 3 Hubbe J. M. 1 Jayne J. T. 18 Jeong H. 21 Jobson B. T. 16 Kassianov E. I. 1 Kleinman L. I. 22 Kluzek C. 1 Knighton B. 17 Kolesar K. R. 13 Kuang C. 22 Kubátová A. 21 Langford A. O. 6 Laskin A. 4 Laulainen N. 1 Marchbanks R. D. 6 Mazzoleni C. 14 Mei F. 22 Moffet R. C. 23 Nelson D. 1 Obland M. D. 3 Oetjen H. 9 Onasch T. B. 18 Ortega I. 9 Ottaviani M. 24 Pekour M. 1 Prather K. A. 11 Radney J. G. 8 Rogers R. R. 3 Sandberg S. P. 6 Sedlacek A. 22 Senff C. J. 6 Senum G. 22 Setyan A. 25 Shilling J. E. 1 Shrivastava M. 1 Song C. 1 Springston S. R. 22 Subramanian R. 26 Suski K. 11 Tomlinson J. 1 Volkamer R. 9 Wallace H. W. 16 Wang J. 22 Weickmann A. M. 6 Worsnop D. R. 18 Yu X.-Y. 1 Zelenyuk A. 27 Zhang Q. 25 Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA Massachusetts Institute of Technology, Cambridge, MA, USA NASA Langley Research Center, Hampton, VA, USA Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, CO, USA University of Nevada, Reno, NV, USA Portland State University, Portland, OR, USA Department of Chemistry and Biochemistry, University of Colorado at Boulder, CO, USA Brechtel Manufacturing, Inc, Hayward, CA, USA University of California, San Diego, CA, USA NASA Goddard Institute for Space Studies, New York, NY, USA Department of Civil and Environmental Engineering, University of California, Davis, CA, USA Atmospheric Science Program, Michigan Technological University, Houghton, MI, USA Los Alamos National Laboratory, Los Alamos, NM, USA Washington State University, Pullman, WA, USA Montana State University, Bozeman, MT, USA Aerodyne Research, Inc., Billerica, MA, USA University of Arkansas, Little Rock, AR, USA Lawrence Berkeley National Laboratory, Berkeley, CA, USA University of North Dakota, ND, USA Brookhaven National Laboratory, Upton, NY, USA University of the Pacific, Stockton, CA, USA NASA Postdoctoral Program Fellow, NASA Goddard Institute for Space Studies, New York, NY, USA Department of Environmental Toxicology, University of California, Davis, CA, USA Droplet Measurements Technologies, Boulder, CO, USA Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA 22 08 2012 12 16 7647 7687 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/12/7647/2012/acp-12-7647-2012.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/7647/2012/acp-12-7647-2012.pdf

Substantial uncertainties still exist in the scientific understanding of the possible interactions between urban and natural (biogenic) emissions in the production and transformation of atmospheric aerosol and the resulting impact on climate change. The US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program's Carbonaceous Aerosol and Radiative Effects Study (CARES) carried out in June 2010 in Central Valley, California, was a comprehensive effort designed to improve this understanding. The primary objective of the field study was to investigate the evolution of secondary organic and black carbon aerosols and their climate-related properties in the Sacramento urban plume as it was routinely transported into the forested Sierra Nevada foothills area. Urban aerosols and trace gases experienced significant physical and chemical transformations as they mixed with the reactive biogenic hydrocarbons emitted from the forest. Two heavily-instrumented ground sites – one within the Sacramento urban area and another about 40 km to the northeast in the foothills area – were set up to characterize the evolution of meteorological variables, trace gases, aerosol precursors, aerosol size, composition, and climate-related properties in freshly polluted and "aged" urban air. On selected days, the DOE G-1 aircraft was deployed to make similar measurements upwind and across the evolving Sacramento plume in the morning and again in the afternoon. The NASA B-200 aircraft, carrying remote sensing instruments, was also deployed to characterize the vertical and horizontal distribution of aerosols and aerosol optical properties within and around the plume. This overview provides: (a) the scientific background and motivation for the study, (b) the operational and logistical information pertinent to the execution of the study, (c) an overview of key observations and initial findings from the aircraft and ground-based sampling platforms, and (d) a roadmap of planned data analyses and focused modeling efforts that will facilitate the integration of new knowledge into improved representations of key aerosol processes and properties in climate models.

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