ALBERT

Description: We have observed lower nitrogen dioxide (NO 2 ) and ozone (O 3 ) during a hot weekend (summer 2010) from aircraft over the entire South Coast Air Basin (SoCAB). Surface concentrations of NO 2 , O 3 and temperature from 1996-2014 corroborate that this lower O 3 on weekends is increasingly likely in recent years. While higher surface O 3 on the weekends (weekend ozone effect, WO3E) remains widespread, the spatial extent and the trend in the probability of WO3E occurrences (P WO3E ) has decreased significantly compared to a decade ago. This decrease is mostly the result of lower O 3 on hot weekends in recent years. P WO3E is lowest in the eastern SoCAB. The major decrease happened during the 2008 economic recession, after which P WO3E has stabilized at a 15-25% lower level throughout most of the basin. Future NO x reductions are likely to be increasingly effective at reducing O 3 pollution initially under hot conditions in the coming decade.

Description: The influence of stratosphere-to-troposphere transport (STT) on surface ozone (O3) concentrations in the greater Los Angeles area during the CalNex and IONS-2010 measurement campaigns has been investigated. Principal component analysis (PCA) of surface O3 measurements from 41 sampling stations indicates that ∼13% of the variance in the maximum daily 8-h average (MDA8) O3 between May 10 and June 19, 2010 was associated with changes of 2–3 day duration linked to the passage of upper-level troughs. Ozonesondes launched from Joshua Tree National Park and airborne lidar measurements show that these changes coincided with the appearance of stratospheric intrusions in the lower troposphere above southern California. The Lagrangian particle dispersion model FLEXPART reproduces most of these intrusions, and supports the conclusion from the PCA that significant transport of stratospheric air to the surface occurred on May 28–30. This intrusion led to a peak 1-h O3 concentration of 88 ppbv at Joshua Tree National Monument near the ozonesonde launch site on May 28, and widespread entrainment of stratospheric air into the boundary layer increased the local background O3 over the entire area to ∼55 ppbv on May 29–30. This background was 10–15 ppbv higher than the baseline O3 in air transported ashore from the Pacific Ocean, and when combined with locally produced O3 led to several exceedances of the current National Ambient Air Quality Standard (NAAQS) on the following day.

Description: Measurements of gaseous ammonia above a montane-subalpine forest in the Colorado mountains show that the role of the forest as a source or sink depends on the atmospheric concentrations. The canopy appeared to be an ammonia source when exposed to air containing low concentrations, but a sink when exposed to air enriched by nearby agricultural sources. The forest-averaged compensation point was 0.8 part per billion by volume at 20 degrees C. The net burden of ammonia and other nitrogen species of anthropogenic origin at this site was much less than at forest sites in the eastern United States and Europe and may provide a valuable resource for this nitrogen-limited ecosystem.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Langford, A O -- Fehsenfeld, F C -- New York, N.Y. -- Science. 1992 Jan 31;255(5044):581-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17792380" target="_blank"〉PubMed〈/a〉

Description: The United States is now experiencing the most rapid expansion in oil and gas production in four decades, owing in large part to implementation of new extraction technologies such as horizontal drilling combined with hydraulic fracturing. The environmental impacts of this development, from its effect on water quality to the influence of increased methane leakage on climate, have been a matter of intense debate. Air quality impacts are associated with emissions of nitrogen oxides (NOx = NO + NO2) and volatile organic compounds (VOCs), whose photochemistry leads to production of ozone, a secondary pollutant with negative health effects. Recent observations in oil- and gas-producing basins in the western United States have identified ozone mixing ratios well in excess of present air quality standards, but only during winter. Understanding winter ozone production in these regions is scientifically challenging. It occurs during cold periods of snow cover when meteorological inversions concentrate air pollutants from oil and gas activities, but when solar irradiance and absolute humidity, which are both required to initiate conventional photochemistry essential for ozone production, are at a minimum. Here, using data from a remote location in the oil and gas basin of northeastern Utah and a box model, we provide a quantitative assessment of the photochemistry that leads to these extreme winter ozone pollution events, and identify key factors that control ozone production in this unique environment. We find that ozone production occurs at lower NOx and much larger VOC concentrations than does its summertime urban counterpart, leading to carbonyl (oxygenated VOCs with a C = O moiety) photolysis as a dominant oxidant source. Extreme VOC concentrations optimize the ozone production efficiency of NOx. There is considerable potential for global growth in oil and gas extraction from shale. This analysis could help inform strategies to monitor and mitigate air quality impacts and provide broader insight into the response of winter ozone to primary pollutants.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Edwards, Peter M -- Brown, Steven S -- Roberts, James M -- Ahmadov, Ravan -- Banta, Robert M -- deGouw, Joost A -- Dube, William P -- Field, Robert A -- Flynn, James H -- Gilman, Jessica B -- Graus, Martin -- Helmig, Detlev -- Koss, Abigail -- Langford, Andrew O -- Lefer, Barry L -- Lerner, Brian M -- Li, Rui -- Li, Shao-Meng -- McKeen, Stuart A -- Murphy, Shane M -- Parrish, David D -- Senff, Christoph J -- Soltis, Jeffrey -- Stutz, Jochen -- Sweeney, Colm -- Thompson, Chelsea R -- Trainer, Michael K -- Tsai, Catalina -- Veres, Patrick R -- Washenfelder, Rebecca A -- Warneke, Carsten -- Wild, Robert J -- Young, Cora J -- Yuan, Bin -- Zamora, Robert -- England -- Nature. 2014 Oct 16;514(7522):351-4. doi: 10.1038/nature13767. Epub 2014 Oct 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] NOAA Earth System Research Laboratory, Boulder, Colorado 80305, USA [2] Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, USA [3] Department of Chemistry, University of York, York YO10 5DD, UK (P.M.E.); Institute of Meteorology and Geophysics, University of Innsbruck, Innsbruck, 6020 Austria (M.G.); Department of Chemistry, Memorial University of Newfoundland, St John's, Newfoundland A1B 3X7, Canada (C.J.Y.). ; NOAA Earth System Research Laboratory, Boulder, Colorado 80305, USA. ; 1] NOAA Earth System Research Laboratory, Boulder, Colorado 80305, USA [2] Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, USA. ; Department of Atmospheric Science, University of Wyoming, Larmie, Wyoming 82070, USA. ; Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77204, USA. ; Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309, USA. ; Air Quality Research Division, Environment Canada, Toronto, Ontario M3H 5T4, Canada. ; Department of Oceanic and Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California 90095, USA. ; 1] NOAA Earth System Research Laboratory, Boulder, Colorado 80305, USA [2] Department of Chemistry, University of York, York YO10 5DD, UK (P.M.E.); Institute of Meteorology and Geophysics, University of Innsbruck, Innsbruck, 6020 Austria (M.G.); Department of Chemistry, Memorial University of Newfoundland, St John's, Newfoundland A1B 3X7, Canada (C.J.Y.).〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25274311" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cooper, Owen R -- Langford, Andrew O -- Parrish, David D -- Fahey, David W -- New York, N.Y. -- Science. 2015 Jun 5;348(6239):1096-7. doi: 10.1126/science.aaa5748.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA. Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, CO 80305, USA. owen.r.cooper@noaa.gov. ; Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, CO 80305, USA. ; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA. Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, CO 80305, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26045425" target="_blank"〉PubMed〈/a〉

Description: A series of deep stratospheric intrusions in late May 2013 increased the daily maximum 8-h surface ozone (O 3 ) concentrations to more than 70 parts-per-billion by volume (ppbv) at rural and urban surface monitors in California and Nevada. This influx of ozone-rich lower stratospheric air and entrained Asian pollution persisted for more than 5 days and contributed to exceedances of the 2008 8-h National Ambient Air Quality Standard (NAAQS) of 75 ppbv on May 21 and 25 in Clark County, NV. Exceedances would also have occurred on May 22 and 23 had the new standard of 70 ppbv been in effect. In this paper, we examine this episode using lidar measurements from a high-elevation site on Angel Peak, NV and surface measurements from NOAA, the Clark County, Nevada Department of Air Quality, the EPA Air Quality System (AQS), and the Nevada Rural Ozone Initiative (NVROI). These measurements, together with analyses from the National Centers for Environmental Prediction/North American Regional Reanalysis (NCEP/NARR), NOAA Geophysical Fluid Dynamics Laboratory (GFDL) AM3, NOAA National Environmental Satellite, Data, and Information Service (NESDIS) Real-time Air Quality Modeling System (RAQMS), and FLEXPART models, show that the exceedances followed entrainment of ~20 to 40 ppbv of lower stratospheric ozone mingled with another 0 to 10 ppbv of ozone transported from Asia, by the unusually deep convective boundary layers above the Mojave Desert. Our analysis suggests that this vigorous mixing can affect both high and low elevations and help explain the springtime ozone maximum in the Southwestern U.S.

Description: A theoretical approach is used to quantify the information available to retrieve cloudphysical properties from data taken by a ground-based spectrometer measuring scatteredsunlight in the near-infrared wavelength region. Three wavelength regions between 0.9and 1.7 mm, each containing water vapor, liquid, and ice absorption features, are examinedusing a differential optical absorption spectroscopy optimal estimation retrieval technique.Cloud properties that can be retrieved include path-integrated liquid water path andpath-integrated ice water path (PLWP and PIWP), cloud liquid and ice temperatures, andthe second moment of the photon path distribution. The accuracy of these cloud propertyretrievals is estimated for a variety of simulated conditions, with key analysis assumptionsidentified. The sensitivity of the measurements in the longest wavelength region toliquid water and ice is high, allowing for accurate estimates of PLWP and PIWP underoptically thin clouds, while the shorter two wavelength bands provide more informationunder optically thicker clouds. Observations of mixed-phase clouds over Barrow, Alaska,are used to illustrate the practicality of the technique. Retrieved LWP values (inferredfrom PLWP) are compared to LWP estimates from a microwave radiometer and anatmospheric emitted radiance interferometer; PIWP estimates are compared to IWPestimates from a millimeter-wave cloud radar. Cloud liquid temperature and photon pathdistribution information retrieved from these data are also presented. Furthermore, wesuggest a technique for combining near-infrared spectral PLWP measurements withmicrowave radiometer observations to estimate cloud droplet effective radius.