Ozone Production Efficiency in the Baltimore-Washington Urban Plume

Monday, 15 December 2014
Linda Hembeck1, Timothy Vinciguerra1, Samantha F Carpenter2, Christopher Loughner1, Timothy P Canty1, Andrew John Weinheimer3, Ronald C Cohen4, Armin Wisthaler5, Alan Fried6, Kenneth E Pickering7, James H Crawford8, Russell R Dickerson1 and Ross J Salawitch2, (1)University of Maryland College Park, College Park, MD, United States, (2)University of Maryland, College Park, MD, United States, (3)NCAR, Boulder, CO, United States, (4)University of California Berkeley, Berkeley, CA, United States, (5)University of Oslo, Department of Chemistry, Oslo, Norway, (6)University of Colorado at Boulder, Boulder, CO, United States, (7)NASA Goddard Space Flight Cent, Greenbelt, MD, United States, (8)NASA Langley Research Center, Hampton, VA, United States
Elevated levels of tropospheric ozone caused by its precursor emissions of NOx and VOCs have a negative impact on human health and crops. Informed regulatory decisions on how to reduce surface ozone in the Baltimore-Washington region can be made with a thorough understanding of urban plume chemistry and climate. The ozone production efficiency (OPE), which is based on the observed ratio of O3 and various nitrogen species, provides a mechanism for quantitatively assessing air quality representation of a key component of the photochemical evolution of urban plumes. We investigate the representation of ozone precursors within the CMAQ (Community Multi-scale Air Quality) air quality model, with a focus on assessing how well the model represents NOx and HOx chemistry. A comprehensive set of atmospheric observations for which OPE can be found and HO2 and RO2can be inferred, is available from NASA’s DISCOVER-AQ campaign for July 2011 in the Baltimore-Washington region. Preliminary results show that the OPE as well as the NOx/NOy ratio in the Baltimore-Washington region derived from measurements is twice as high as within CMAQ, and that isoprene and formaldehyde are too low within CMAQ. Implications for policy will be briefly discussed.