Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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Observational Evaluation of Mobile Source Emissions

Gregory Frost, Stuart McKeen, Michael Trainer, Ken Aikin, Jeff Peischl, Thomas Ryerson, John Holloway, Gabrielle Pétron, Pieter Tans, and Robert Harley

Ambient ratios of NO_x , CO, and CO_2 sampled by aircraft in Houston and Dallas during the 2000 and 2006 Texas Air Quality Study (TexAQS) are compared with each other and with observations at a Houston highway tunnel. From these measurements we estimate 2000 and 2006 emissions for Houston and Dallas mobile sources. The observations demonstrate time-of-day variations in the relative contributions from gasoline and diesel combustion which are consistent with known traffic patterns. We incorporate CO_2 emissions derived from the Federal Highway Administration’s motor vehicle fuel use statistics into the EPA’s National Emission Inventory (NEI), resulting in an emission data set for NO_x , CO, and CO_2 with 4-km spatial and hourly temporal resolution. Comparison of the emission ratios derived from the TexAQS observations with this inventory allows a direct evaluation of the NEI mobile source NO_x and CO emissions.