Improving Chemical Mechanisms of Reactive Nitrogen from Snowpack and Transportation in a Global Chemical Transport Model

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The goal of this project is to improve the chemical mechanisms associated with emissions of global nitrogen oxides (NOx) and nitrous acid (HONO) from snowpack and HONO from the on-road gasoline and diesel sectors. The PI hypothesizes that the photolysis (reaction by sunlight) of nitrate aerosols in the snowpack leads to the production of NOx and HONO in the atmosphere. This work will improve the modeling of ozone production and air quality in the US.

The objectives of this proposal are to (1) parameterize representations of the NOx/HONO chemical mechanisms associated with snowpack emissions, and HONO chemical mechanisms associated with on-road gasoline and diesel subsector emissions and implement these in the global GEOS-Chem chemical transport model; and (2) quantify the impacts of global missing sources of NOx/HONO production from snowpack, and on-road gasoline and diesel subsectors in transportation on atmospheric oxidants and air quality. The updated NOx/HONO chemical mechanisms in GEOS-Chem will be evaluated against global surface HONO and nitrogen dioxide (NO2) observations, as well as tropospheric NO2 column density measurements from satellite observations.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.