Winter Photochemistry Underlying High Ozone in an Oil and Gas Producing Region
Steven S Brown1, Peter M Edwards2, Dr. James Roberts, PhD3, Ravan Ahmadov4, Robert M Banta5, Joost A de Gouw6, William P Dube7, Robert Alexander Field8, Jessica Gilman3, Martin Graus9, Dr. Detlev Helmig10, Abigail Koss11, Andrew O'Neil Langford12, Barry L Lefer13, Brian M Lerner14, Stuart A McKeen15, Shao-Meng Li16, Shane M Murphy17, David D Parrish18, Christoph J Senff18, Jochen Stutz19, Chelsea R Thompson10, Michael Trainer20, Patrick R Veres21, Carsten Warneke7, Robert J Wild22, Cora Young23, Bin Yuan2, Robert J Zamora24 and Rebecca A Washenfelder7, (1)NOAA, Earth System Research Laboratory, Boulder, CO, United States, (2)CIRES, Boulder, CO, United States, (3)NOAA Chemical Sciences Laboratory, Boulder, United States, (4)University of Colorado at Boulder, CIRES, Boulder, CO, United States, (5)NOAA/ESRL/CSD, Boulder, CO, United States, (6)University of Colorado Boulder, Department of Chemistry, Boulder, United States, (7)NOAA Boulder, Boulder, CO, United States, (8)University of Wyoming, Laramie, WY, United States, (9)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (10)University of Colorado at Boulder, Institute of Arctic and Alpine Research, Boulder, CO, United States, (11)University of Colorado at Boulder, Boulder, CO, United States, (12)NOAA ESRL, Boulder, CO, United States, (13)University of Houston, Earth and Atmospheric Sciences, Houston, TX, United States, (14)Aerodyne Research, Inc., Billerica, MA, United States, (15)NOAA ESRL/CSL and CU Boulder/CIRES, Boulder, CO, United States, (16)Environment Canada Toronto, Toronto, ON, Canada, (17)University of Wyoming, Atmospheric Science, Laramie, United States, (18)NOAA, Boulder, CO, United States, (19)University of California Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, (20)NOAA Earth System Research Lab, Boulder, CO, United States, (21)NOAA Boulder, Boulder, United States, (22)Colorado University/NOAA/ESRL, Boulder, CO, United States, (23)York University, Department of Chemistry, Toronto, ON, Canada, (24)NOAA/OAR R/PSD2, Boulder, CO, United States
Abstract:
Ozone formation during wintertime in oil and gas producing basins of the Rocky Mountain West now accounts for some of the highest ozone pollutant concentrations observed in the U.S. These events are scientifically challenging, occurring only during cold, snow covered periods when meteorological inversions concentrate pollutants near the surface, but when incident solar actinic flux that initiates photochemical reactions is at or near its minimum. A near-explicit chemical model that incorporates detailed measurements obtained during three successive winter field studies in the Uintah Basin, Utah, accurately reproduces the observed buildup of ozone and other photochemically generated species. It also identifies the sources of free radicals that drive this unusual photochemistry, and quantifies their relative contributions. Although sharing the same basic atmospheric chemistry, winter ozone formation differs from its summertime, urban counterpart in its dependence upon the relative concentrations of volatile organic compounds (VOCs) and nitrogen oxide (NOx) precursors. Observed NOx mixing ratios in the Uintah basin are lower than is typical of urban areas, while VOC levels are significantly larger. These extreme VOC concentrations allow for nearly optimal efficiency of ozone production from the available NOx. This analysis will inform the design of mitigation strategies and provide insight into the response of winter ozone to primary air pollutants in other regions, particularly those where oil and gas development is contemplated.
