posted on 2023-11-30, 20:38authored byKatelyn
A. Yu, Meng Li, Colin Harkins, Jian He, Qindan Zhu, Bert Verreyken, Rebecca H. Schwantes, Ronald C. Cohen, Brian C. McDonald, Robert A. Harley
The extent to which
emission control technologies and policies
have reduced anthropogenic NOx emissions
from motor vehicles is large but uncertain. We evaluate a fuel-based
emission inventory for southern California during the June 2021 period,
coinciding with the Re-Evaluating the Chemistry of Air Pollutants
in CAlifornia (RECAP-CA) field campaign. A modified version of the
Fuel-based Inventory of Vehicle Emissions (FIVE) is presented, incorporating
1.3 km resolution gridding and a new light-/medium-duty diesel vehicle
category. NOx concentrations and weekday–weekend
differences were predicted using the WRF-Chem model and evaluated
using satellite and aircraft observations. Model performance was similar
on weekdays and weekends, indicating appropriate day-of-week scaling
of NOx emissions and a reasonable distribution
of emissions by sector. Large observed weekend decreases in NOx are mainly due to changes in on-road vehicle
emissions. The inventory presented in this study suggests that on-road
vehicles were responsible for 55–72% of the NOx emissions in the South Coast Air Basin, compared
to the corresponding fraction (43%) in the planning inventory from
the South Coast Air Quality Management District. This fuel-based inventory
suggests on-road NOx emissions that are
1.5 ± 0.4, 2.8 ± 0.6, and 1.3 ± 0.7 times the reference
EMFAC model estimates for on-road gasoline, light- and medium-duty
diesel, and heavy-duty diesel, respectively.