Spatio-temporal Estimates of CO2 Emissions in the Los Angeles Basin from On-road and Airport Traffic

Abstract:

Characterizing the spatio-temporal distribution of fossil fuel CO₂ (FFCO₂) emissions in urban landscapes is challenging. We use Hestia, an innovative “bottom up” approach for estimating FFCO₂ emissions in the Los Angeles (LA) megacity and Southern California Air Basin (SCAB) which account for ~53% of the FFCO₂ emissions in California. Hestia-LA, in coordination with “top down” atmospheric CO₂ measurements, will provide baseline FFCO₂ emissions, help monitor changes in emissions, and develop emissions mitigation policies. Hestia-LA characterizes FFCO₂ emissions at the building/street spatial scale (10-100 m) and at hourly time steps in the basin by combining data on residential and commercial building emissions, industrial processes, electricity production, and different transportation sectors. We report here on the construction of the spatial and temporal structure in two key transportation sectors within the SCAB: on-road vehicle (46%) and aircraft (2%) emissions.

We quantified on-road traffic emissions by merging traffic data from Southern California Association of Governments, California Freeway Performance Measurement System and modeled motor vehicle emissions from EPA’s NMIM model. Preliminary analysis shows that (1) LA and Orange counties dominate the annual FFCO2 emissions from urban freeways and arterials, and (2) LA county has a wider peak traffic period during weekdays (2-6pm) than the other four counties (4-5pm).

We characterized airport emissions by integrating information from Federal Aviation Administration, Los Angeles World Airports, and Airnav LLC for the temporal structure of aircraft arrivals and departures, and the National Emissions Inventory for total annual aircraft emissions. We categorized the 47 airports in LA basin based on the volume and type (commercial, general aviation and military) of aircraft traffic, and then assigned appropriate hour-of-day and day-of-week traffic volume-specific CO2 emission patterns to each airport. We found that Los Angeles international airport has a unique diurnal traffic pattern with a broad peak during 6am-9pm and differs from the more prevalent general aviation airports which peak in traffic during 10am-4pm.