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Published June 16, 2013 | Published
Journal Article Open

The 2010 California Research at the Nexus of Air Quality and Climate Change (CalNex) field study


The California Research at the Nexus of Air Quality and Climate Change (CalNex) field study was conducted throughout California in May, June, and July of 2010. The study was organized to address issues simultaneously relevant to atmospheric pollution and climate change, including (1) emission inventory assessment, (2) atmospheric transport and dispersion, (3) atmospheric chemical processing, and (4) cloud-aerosol interactions and aerosol radiative effects. Measurements from networks of ground sites, a research ship, tall towers, balloon-borne ozonesondes, multiple aircraft, and satellites provided in situ and remotely sensed data on trace pollutant and greenhouse gas concentrations, aerosol chemical composition and microphysical properties, cloud microphysics, and meteorological parameters. This overview report provides operational information for the variety of sites, platforms, and measurements, their joint deployment strategy, and summarizes findings that have resulted from the collaborative analyses of the CalNex field study. Climate-relevant findings from CalNex include that leakage from natural gas infrastructure may account for the excess of observed methane over emission estimates in Los Angeles. Air-quality relevant findings include the following: mobile fleet VOC significantly declines, and NO_x emissions continue to have an impact on ozone in the Los Angeles basin; the relative contributions of diesel and gasoline emission to secondary organic aerosol are not fully understood; and nighttime NO_3 chemistry contributes significantly to secondary organic aerosol mass in the San Joaquin Valley. Findings simultaneously relevant to climate and air quality include the following: marine vessel emissions changes due to fuel sulfur and speed controls result in a net warming effect but have substantial positive impacts on local air quality.

Additional Information

© 2013 American Geophysical Union. Received 23 October 2012; revised 11 March 2013; accepted 12 March 2013; published 13 June 2013. We thank L. Dolislager (CARB) for the description of existing long-term criteria pollutant, greenhouse gas, and meteorological measurement sites in California. We also thank G. Sanger and B. Ochs (NWS San Joaquin Valley/Hanford Weather Forecast Office) and L. Dolislager and J. Pederson (CARB) for meteorological forecast summaries. The R/V Atlantis cruise and NOAA P-3 flights were supported, in part, by the NOAA Climate Change and, in part, by the NOAA Air Quality programs. NOAA Twin Otter flights were supported by the NOAA Air Quality program and the California Air Resources Board. CIRPAS Twin Otter flights were supported by the NOAA Climate Change program under contract NA090AR4310128. NASA B200 flights were supported by the DOE Atmospheric Systems Research Program and the NASA Radiation Sciences and Tropospheric Chemistry programs. Data collection at the CALGEM tall tower sites was supported by the NOAA Office of Global Programs, the California Energy Commission (CEC) Public Interest Environmental Research Program, and LBNL Laboratory Directed Research through the U.S. Department of Energy under contract DE-AC02-05CH11231. Researchers at the ground sites were supported by the California Air Resources Board, the NOAA Office of Global Programs, the US Department of Energy, and the US National Science Foundation.

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