ALBERT

Description: Direct measurements of air-sea heat, momentum, and mass (including CO2, DMS, and water vapor) fluxes using the direct covariance method were made over the open ocean from the NOAA R/V Ronald H. Brown during the Southern Ocean Gas Exchange (SO GasEx) program. Observations of fluxes and the physical processes associated with driving air-sea exchange are key components of SO GasEx. This paper focuses on the exchange of CO2 and the wind speed dependency of the transfer velocity, k, used to model the CO2 flux between the atmosphere and ocean. A quadratic dependence of k on wind speed based on dual tracer experiments is most frequently encountered in the literature. However, in recent years, bubble-mediated enhancement of k, which exhibits a cubic relationship with wind speed, has emerged as a key issue for flux parameterization in high-wind regions. Therefore, a major question addressed in SO GasEx is whether the transfer velocities obey a quadratic or cubic relationship with wind speed. After significant correction to the flux estimates (primarily due to moisture contamination), the direct covariance CO2 fluxes confirm a significant enhancement of the transfer velocity at high winds compared with previous quadratic formulations. Regression analysis suggests that a cubic relationship provides a more accurate parameterization over a wind speed range of 0 to 18 m s−1. The Southern Ocean results are in good agreement with the 1998 GasEx experiment in the North Atlantic and a recent separate field program in the North Sea.

Description: Updates for the Coupled Ocean-Atmosphere Response Experiment (COARE) physically based meteorological and gas transfer bulk flux algorithms are examined. The current versions are summarized and a generalization of the gas transfer codes to 79 gases is described. The current meteorological version COARE3.0 was compared with a collection of 26,700 covariance observations of drag and heat transfer coefficients (compiled from three independent research groups). The algorithm agreed on average to within 5% with observations for a wind speed range of 2 to 18 m s−1. Covariance observations of CO2 and dimethyl sulfide (DMS) gas transfer velocity k were normalized to Schmidt number 660 and compared to an ensemble of gas flux observations from six research groups and nine field programs. A reasonable fit of the mean k660 versus U10n values was obtained for both CO2 and DMS with a new version of the COARE gas transfer algorithm (designated COAREG3.1) using friction velocity associated with viscous (tangential) stress, u*ν, in the nonbubble term. In the wind speed range 5 to 16 m s−1, tracer-derived estimates of k660 are 10% to 20% lower than the CO2 covariance estimates presented here.

Description: A ship-based eddy covariance ozone flux system was deployed to investigate the magnitude and variability of ozone surface fluxes over the open ocean. The flux experiments were conducted on five cruises on board the NOAA research vessel Ronald Brown during 2006–2008. The cruises covered the Gulf of Mexico, the southern as well as northern Atlantic, the Southern Ocean, and the persistent stratus cloud region off Chile in the eastern Pacific Ocean. These experiments resulted in the first ship-borne open-ocean ozone flux measurement records. The median of 10 min oceanic ozone deposition velocity (vd) results from a combined ∼ 1700 h of observations ranged from 0.009 to 0.034 cm s−1. For the Gulf of Mexico cruise (Texas Air Quality Study (TexAQS)) the median vd (interquartile range) was 0.034 (0.009–0.065) cm s−1 (total number of 10 min measurement intervals, Nf = 1953). For the STRATUS cruise off the Chilean coast, the median vd was 0.009 (0.004–0.037) cm s−1 (Nf = 1336). For the cruise from the Gulf of Mexico and up the eastern U.S. coast (Gulf of Mexico and East Coast Carbon cruise (GOMECC)) a combined value of 0.018 (0.006–0.045) cm s−1 (Nf = 1784) was obtained (from 0.019 (−0.014–0.043) cm s−1, Nf = 663 in the Gulf of Mexico, and 0.018 (−0.004–0.045) cm s−1, Nf = 1121 in the North Atlantic region). The Southern Ocean Gas Exchange Experiment (GasEx) and African Monsoon Multidisciplinary Analysis (AMMA), the Southern Ocean and northeastern Atlantic cruises, respectively, resulted in median ozone vd of 0.009 (−0.005–0.026) cm s−1 (Nf = 2745) and 0.020 (−0.003–0.044) cms−1 (Nf = 1147). These directly measured ozone deposition values are at the lower end of previously reported data in the literature (0.01–0.12 cm s−1) for ocean water. Data illustrate a positive correlation (increase) of the oceanic ozone uptake rate with wind speed, albeit the behavior of the relationship appears to differ during these cruises. The encountered wide range of meteorological and ocean biogeochemical conditions is used to investigate fundamental drivers of oceanic O3 deposition and for the evaluation of a recently developed global oceanic O3 deposition modeling system.

Description: Environmental Science & Technology DOI: 10.1021/es405046r

Description: After methane, ethane is the most abundant hydrocarbon in the remote atmosphere. It is a precursor to tropospheric ozone and it influences the atmosphere's oxidative capacity through its reaction with the hydroxyl radical, ethane's primary atmospheric sink. Here we present the longest continuous record of global atmospheric ethane levels. We show that global ethane emission rates decreased from 14.3 to 11.3 teragrams per year, or by 21 per cent, from 1984 to 2010. We attribute this to decreasing fugitive emissions from ethane's fossil fuel source--most probably decreased venting and flaring of natural gas in oil fields--rather than a decline in its other major sources, biofuel use and biomass burning. Ethane's major emission sources are shared with methane, and recent studies have disagreed on whether reduced fossil fuel or microbial emissions have caused methane's atmospheric growth rate to slow. Our findings suggest that reduced fugitive fossil fuel emissions account for at least 10-21 teragrams per year (30-70 per cent) of the decrease in methane's global emissions, significantly contributing to methane's slowing atmospheric growth rate since the mid-1980s.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Simpson, Isobel J -- Sulbaek Andersen, Mads P -- Meinardi, Simone -- Bruhwiler, Lori -- Blake, Nicola J -- Helmig, Detlev -- Rowland, F Sherwood -- Blake, Donald R -- England -- Nature. 2012 Aug 23;488(7412):490-4. doi: 10.1038/nature11342.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California-Irvine, Irvine, California 92697, USA. isimpson@uci.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22914166" 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: Recent measurements over the Northern Hemisphere indicate that the long-term decline in the atmospheric burden of ethane (C 2 H 6 ) has ended, and the abundance increased dramatically between 2010 and 2014. The rise in C 2 H 6 atmospheric abundances has been attributed to oil and natural gas extraction in North America. Existing global C 2 H 6 emission inventories are based on outdated activity maps that do not account for current oil and natural gas exploitation regions. We present an updated global C 2 H 6 emission inventory based on 2010 satellite-derived CH 4 fluxes with adjusted C 2 H 6 emissions over the U.S. from the National Emission Inventory (NEI 2011). We contrast our global 2010 C 2 H 6 emission inventory with one developed for 2001. The C 2 H 6 difference between global anthropogenic emissions is subtle (7.9 versus 7.2 Tg yr −1 ), but the spatial distribution of the emissions is distinct. In the 2010 C 2 H 6 inventory, fossil fuel sources in the Northern Hemisphere represent half of global C 2 H 6 emissions and 95% of global fossil fuel emissions. Over the U.S., un-adjusted NEI 2011 C 2 H 6 emissions produce mixing ratios that are 14–50 % of those observed by aircraft observations (2008–2014). When the NEI 2011 C 2 H 6 emission totals are scaled by a factor of 1.4, the GEOS-Chem model largely reproduces a regional suite of observations, with the exception of the central U.S., where it continues to under-predict observed mixing ratios in the lower troposphere. We estimate monthly mean contributions of fossil fuel C 2 H 6 emissions to ozone and peroxyacetyl nitrate surface mixing ratios over North America of ~1% and ~8%, respectively.