Ponente
Descripción
The COVID-19 pandemic has caused significant changes in emissions of ozone and aerosol precursors. This has been a challenge for air quality forecast models to adapt to evolving emissions associated with the lockdown and recovery periods. Traditionally, the development of bottom-up emission inventories is a time-intensive activity that often involves a multi-year lag. Here, we explore the use of monthly emission adjustments in near real-time using publicly available energy and economic datasets of the US. We update mobile source emissions, using the Fuel-based Inventory of Vehicle Emissions (FIVE), and point and area source emissions on a monthly basis. Our bottom-up inventory suggests that in April 2020, US nitrogen oxides (NOx) emissions fell by ~20% in 2020 versus 2019. The reduction was mainly contributed by mobile source engines, as well as industrial sources and electricity generation. In July 2020, emissions had rebounded, but were still lower by ~10% in 2020 versus 2019. We evaluate the emission inventory with satellite tropospheric nitrogen dioxide (NO2) columns from the TROPOspheric Monitoring Instrument (TROPOMI). Over urban source regions, the inventory captures the COVID-19 perturbations in TROPOMI NO2 observed from April through July. Over isolated point source regions, TROPOMI NO2 fell by -42% in April and -29% in July, illustrating impacts on the economy from the pandemic. Overall, the monthly adjustment factors developed for mobile source and industrial point sources are promising for adjusting emission inventories in near real-time for air quality forecast models.
