Mountain Valley Circulation and Ozone Transport in the Colorado Front Range

Abstract:

Two major field campaigns - The NSF/NCAR and State of Colorado Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) and the 4^thdeployment of the NASA DISCOVER-AQ – were conducted in summer 2014 to study summertime ozone pollution in the Northern Colorado Front Range Metropolitan Area (NFRMA), an area that is in non-attainment of the current ozone standards. Characterizing and modeling air quality in the NFRMA poses large challenges due to the complex terrain and meteorology as well as the mix of diverse pollution source. The comprehensive suite of aircraft and ground-based sampling of meteorological parameters and chemical tracers provides a highly detailed view of the factors impacting air quality in the NFRMA.

The focus in this presentation is on episodes during the campaign period when mountain-valley circulation transported pollution from the NFRMA to the pristine mountain areas to the West. We use simulations with the WRF-Chem model together with the field campaign data to examine the pathways and chemical processes that occur during these transport events, use modeled and measured tracers to distinguish the origin, and assess the resulting impacts on the mountain regions.