Publication Date:
2016-01-11
Description:
We developed a new nitrogen oxides (NO x ) and carbon monoxide (CO) emission inventory for the Los Angeles-South Coast Air Basin (SoCAB) expanding the Fuel-based Inventory for motor-Vehicle Emissions (FIVE) and applied it in regional chemical transport modeling focused on the California Nexus of Air Quality and Climate Change (CalNex) 2010 field campaign. The weekday NO x emission over the SoCAB in 2010 is 620 metric tons day −1 while the weekend emission is 410 metric tons day −1 . The NO x emission decrease on weekends is caused by reduced diesel truck activities. Weekday and weekend CO emissions over this region are similar: 2340 and 2180 metric tons day −1 , respectively. Previous studies reported large discrepancies between the airborne observations of NO x and CO mixing ratios and the model simulations for CalNex based on the available bottom-up emission inventories. Utilizing the newly developed emission inventory in this study, the simulated NO x and CO mixing ratios agree with the observations from the airborne and the ground-based in-situ and remote-sensing instruments during the field study. The simulations also reproduce the weekly cycles of these chemical species. Both the observations and the model simulations indicate that decreased NO x on weekends leads to enhanced photochemistry and increase of O 3 and O x (=O 3 + NO 2 ) in the basin. The emission inventory developed in this study can be extended to different years and other urban regions in the US to study the long-term trends in O 3 and its precursors with regional chemical transport models.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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