California's ambient ozone concentrations have two principal contributions: U.S. background ozone and enhancements produced from anthropogenic precursor emissions; only the latter effectively respond to California emission controls. From 1980 to 2015 ozone has been monitored in eight air basins in Southern California. The temporal evolution of the largest measured concentrations, i.e., those that define the ozone design value (ODV) upon which the National Ambient Air Quality Standard (NAAQS) is based, is described very well by an exponential decrease on top of a positive offset. We identify this offset as the ODV due to the U.S. background ozone (i.e., the concentration that would be present if U.S. anthropogenic precursor emissions were reduced to zero) and is estimated to be 62.0 +/- 1.9 ppb in six of the basins. California's emission control efforts have reduced the anthropogenic ozone enhancements by a factor of similar to 5 since 1980. However, assuming that the current rate of exponential decrease is maintained and that U.S. background ODV remains constant, projections of the past decrease suggest that similar to 35 years of additional emission control efforts will be required to reach the new NAAQS of 70 ppb in the Los Angeles area. The growing predominance of U.S. background ozone contributions has shifted the maximum ozone concentrations in all air basins from later to earlier in the summer. Comparisons indicate that currently accepted model estimates of U.S. background ozone concentrations in Southern California are somewhat underestimated; thus, reducing ozone in this region to the 2015 NAAQS may be more difficult than currently expected. Plain Language Summary Over the past decades, ozone air quality in Southern California has been greatly improved, but the National Ambient Air Quality Standard (NAAQS) has not yet been achieved in much of the region. The ozone standard is based on the rare, highest recorded concentrations (similar to 98th percentile). A simple mathematical function is shown to provide an excellent description of the decrease in these ozone concentrations, which allows some implications to be inferred. Since 1980 the anthropogenic contribution to these concentrations has been reduced by a factor of similar to 5. However, the contribution of background ozone is estimated as similar to 89% of the NAAQS. Since this background contribution is so large, projection of the past rate of decrease of the anthropogenic contribution into the future suggests that similar to 35 years of additional emission control efforts will be required to reach the new NAAQS of 70 ppb in the Los Angeles region. The model calculations of the background ozone contribution that were considered in the formulation of the new NAAQS underestimate the background contribution. Thus, reducing Southern California ozone concentrations to the NAAQS may be more difficult than currently expected.
Lerner, B. M.; Gilman, J. B.; Aikin, K. C.; Atlas, E. L.; Goldan, P. D.; Graus, M.; Hendershot, R.; Isaacman-VanWertz, G. A.; Koss, A.; Kuster, W. C.; Lueb, R. A.; McLaughlin, R. J.; Peischl, J.; Sueper, D.; Ryerson, T. B.; Tokarek, T. W.; Warneke, C.; Yuan, B.; de Gouw, J. A.;
Volatile organic compounds were quantified during two aircraft-based field campaigns using highly automated, whole air samplers with expedited post-flight analysis via a new custom-built, field-deployable gas chromatography-mass spectrometry instrume...
Tevlin, A. G.; Li, Y.; Collett, J. L.; McDuffie, E. E.; Fischer, E. V.; Murphy, J. G.;
Published Date:
2017
Source:
Journal of Geophysical Research-Atmospheres, 122(22), 12468-12487.
Description:
Ammonia (NH3) mixing ratios were measured between the surface and 280m aboveground level from a moveable carriage at the Boulder Atmospheric Observatory tower in summer 2014 as part of the Front Range Air Pollution and Photochemistry Experiment. The ...
Colette, A.; Andersson, C.; Manders, A.; Mar, K.; Mircea, M.; Pay, M. T.; Raffort, V.; Tsyro, S.; Cuvelier, C.; Adani, M.; Bessagnet, B.; Bergstrom, R.; Briganti, G.; Butler, T.; Cappelletti, A.; Couvidat, F.; D'Isidoro, M.; Doumbia, T.; Fagerli, H.; Granier, C.; Heyes, C.; Klimont, Z.; Ojha, N.; Otero, N.; Schaap, M.; Sindelarova, K.; Stegehuis, A. I.; Roustan, Y.; Vautard, R.; van Meijgaard, E.; Vivanco, M. G.; Wind, P.;
Published Date:
2017
Source:
Geoscientific Model Development, 10(9), 3255-3276.
Description:
The EURODELTA-Trends multi-model chemistry-transport experiment has been designed to facilitate a better understanding of the evolution of air pollution and its drivers for the period 1990-2010 in Europe. The main objective of the experiment is to as...
We describe the University of Colorado mobile Solar Occultation Flux instrument (CU mobile SOF). The instrument consists of a digital mobile solar tracker that is coupled to a Fourier transform spectrometer (FTS) of 0.5 cm (-1) resolution and a UV-vi...
Giordano, M. R.; Kalnajs, L. E.; Avery, A.; Goetz, J. D.; Davis, S. M.; DeCarlo, P. F.;
Published Date:
2017
Source:
Atmospheric Chemistry and Physics, 17(1), 1-20.
Description:
Understanding the sources and evolution of aerosols is crucial for constraining the impacts that aerosols have on a global scale. An unanswered question in atmospheric science is the source and evolution of the Antarctic aerosol population. Previous ...
Sayers, M. J.; Grimm, A. G.; Shuchman, R. A.; Bosse, K. R.; Fahnenstiel, G. L.; Ruberg, S. A.; Leshkevich, G. A.;
Published Date:
2019
Source:
Journal of Great Lakes Research, 45(3), 508-521.
Description:
Blooms of harmful cyanobacteria (cyanoHABs) have occurred on an annual basis in western Lake Erie for more than a decade. Previously, we developed and validated an algorithm to map the extent of the submerged and surface scum components of cyanoHABs ...
Hill, M. C.; Bendlin, A. R.; Van Cise, A. M.; Milette-Winfree, A.; Ligon, A. D.; Ü, A. C.; Deakos, M. H.; Oleson, E. M.;
Published Date:
2019
Source:
Marine Mammal Science, 35(3), 797-824.
Description:
Abstract Little is known about short-finned pilot whales (Globicephala macrorhynchus) in the western North Pacific outside of Japanese coastal waters. To expand understanding of short-finned pilot whale ecology in the region, we conducted small-boat ...
Journal of Advances in Modeling Earth Systems, 9(1), 627-646.
Description:
Low and high clouds of shallow extent, especially stratocumulus and even more so for high-level cirrus clouds that reside where vertical resolution is particularly coarse, are poorly represented in large-scale models such as global climate models and...
Butler, A. H.; Sjoberg, J. P.; Seidel, D. J.; Rosenlof, K. H.;
Published Date:
2017
Source:
Earth System Science Data, 9(1), 63-76.
Description:
Major, sudden midwinter stratospheric warmings (SSWs) are large and rapid temperature increases in the winter polar stratosphere are associated with a complete reversal of the climatological westerly winds (i.e., the polar vortex). These extreme even...
Sayers, M. J.; Bosse, K. R.; Shuchman, R. A.; Ruberg, S. A.; Fahnenstiel, G. L.; Leshkevich, G. A.; Stuart, D. G.; Johengen, T. H.; Burtner, A. M.; Palladino, D.;
Published Date:
2019
Source:
Journal of Great Lakes Research, 45(3), 490-507.
Description:
Lake Erie has experienced dramatic changes in water quality over the past several decades requiring extensive monitoring to assess effectiveness of adaptive management strategies. Remote sensing offers a unique potential to provide synoptic monitorin...
Jensen, E. J.; Karcher, B.; Ueyama, R.; Pfister, L.; Bui, T. V.; Diskin, G. S.; DiGangi, J. P.; Woods, S.; Lawson, R. P.; Froyd, K. D.; Murphy, D. M.;
Published Date:
2018
Source:
Journal of Geophysical Research-Atmospheres, 123(21), 12210-12227.
Description:
Recent laboratory experiments have advanced our understanding of heterogeneous ice nucleation at low temperatures. We use these laboratory results, along with field measurements of aerosol composition, to constrain a parameterization of heterogeneous...
Stauffer, R. M.; Thompson, A. M.; Oltmans, S. J.; Johnson, B. J.;
Published Date:
2017
Source:
Journal of Geophysical Research-Atmospheres, 122(2), 1261-1280.
Description:
Much attention has been focused on the transport of ozone (O-3) to the western U.S., particularly given the latest revision of the National Ambient Air Quality Standard to 70 parts per billion by volume (ppbv) of O-3. This makes quantifying the contr...
Jathar, S. H.; Heppding, C.; Link, M. F.; Farmer, D. K.; Akherati, A.; Kleeman, M. J.; de Gouw, J. A.; Veres, P. R.; Roberts, J. M.;
Published Date:
2017
Source:
Atmospheric Chemistry and Physics, 17(14), 8959-8970.
Description:
Isocyanic acid (HNCO), an acidic gas found in tobacco smoke, urban environments, and biomass-burning-affected regions, has been linked to adverse health outcomes. Gasoline-and diesel-powered engines and biomass burning are known to emit HNCO and hypo...
Barkley, H. C.; Cohen, A. L.; Mollica, N. R.; Brainard, R. E.; Rivera, H. E.; DeCarlo, T. M.; Lohmann, G. P.; Drenkard, E. J.; Alpert, A. E.; Young, C. W.; Vargas-Ángel, B.; Lino, K. C.; Oliver, T. A.; Pietro, K. R.; Luu, V. H.;
Published Date:
2018
Source:
Communications Biology, 1(1), 177.
Description:
The oceans are warming and coral reefs are bleaching with increased frequency and severity, fueling concerns for their survival through this century. Yet in the central equatorial Pacific, some of the world’s most productive reefs regularly experie...
Yuan, B.; Coggon, M. M.; Koss, A. R.; Warneke, C.; Eilerman, S.; Peischl, J.; Aikin, K. C.; Ryerson, T. B.; de Gouw, J. A.;
Published Date:
2017
Source:
Atmospheric Chemistry and Physics, 17(8), 4945-4956.
Description:
Concentrated animal feeding operations (CAFOs) emit a large number of volatile organic compounds (VOCs) to the atmosphere. In this study, we conducted mobile laboratory measurements of VOCs, methane (CH4) and ammonia (NH3) downwind of dairy cattle, b...
Observations of atmospheric trace gases in the tropical upper troposphere (UT), tropical tropopause layer (TTL), and lower stratosphere (LS) require dedicated measurement platforms and instrumentation. Here we present a new limb-scanning Differential...
Palm, B. B.; Campuzano-Jost, P.; Day, D. A.; Ortega, A. M.; Fry, J. L.; Brown, S. S.; Zarzana, K. J.; Dube, W.; Wagner, N. L.; Draper, D. C.; Kaser, L.; Jud, W.; Karl, T.; Hansel, A.; Gutierrez-Montes, C.; Jimenez, J. L.;
Published Date:
2017
Source:
Atmospheric Chemistry and Physics, 17(8), 5331-5354.
Description:
Ambient pine forest air was oxidized by OH, O-3, or NO3 radicals using an oxidation flow reactor (OFR) during the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen - Rocky Mountain Biogenic Aero...
Long, C. S.; Fujiwara, M.; Davis, S.; Mitchell, D. M.; Wright, C. J.;
Published Date:
2017
Source:
Atmospheric Chemistry and Physics, 17(23), 14593-14629.
Description:
Two of the most basic parameters generated from a reanalysis are temperature and winds. Temperatures in the reanalyses are derived from conventional (surface and balloon), aircraft, and satellite observations. Winds are observed by conventional syste...
Perring, A. E.; Schwarz, J. P.; Markovic, M. Z.; Fahey, D. W.; Jimenez, J. L.; Campuzano-Jost, P.; Palm, B. D.; Wisthaler, A.; Mikoviny, T.; Diskin, G.; Sachse, G.; Ziemba, L.; Anderson, B.; Shingler, T.; Crosbie, E.; Sorooshian, A.; Yokelson, R.; Gao, R. S.;
Published Date:
2017
Source:
Journal of Geophysical Research-Atmospheres, 122(2), 1086-1097.
Description:
Water uptake by black carbon (BC)-containing aerosol was quantified in North American wildfire plumes of varying age (1 to similar to 40 h old) sampled during the SEAC(4)RS mission (2013). A Humidified Dual SP2 (HD-SP2) is used to optically size BC-c...
Miller, C. C.; Jacob, D. J.; Marais, E. A.; Yu, K. R.; Travis, K. R.; Kim, P. S.; Fisher, J. A.; Zhu, L.; Wolfe, G. M.; Hanisco, T. F.; Keutsch, F. N.; Kaiser, J.; Min, K. E.; Brown, S. S.; Washenfelder, R. A.; Abad, G. G.; Chance, K.;
Published Date:
2017
Source:
Atmospheric Chemistry and Physics, 17(14), 8725-8738.
Description:
Glyoxal (CHOCHO) is produced in the atmosphere by the oxidation of volatile organic compounds (VOCs). Like formaldehyde (HCHO), another VOC oxidation product, it is measurable from space by solar backscatter. Isoprene emitted by vegetation is the dom...
Nitrous oxide (N2O) is a potent long‐lived greenhouse gas (GHG) and the strongest current emissions of global anthropogenic stratospheric ozone depletion weighted by its ozone depletion potential. In California, N2O is the third largest contributor...
US ambient ozone concentrations have two components: US background ozone and enhancements produced from the country's anthropogenic precursor emissions. Only the enhancements effectively respond to national emission controls. We investigate the tempo...