A study of the impact of aged boreal fire emissions on the composition of the remote midlatitude lower free troposphere, using measurements at the PICO-NARE station.

Emphasis Area: Atmospheric Chemistry

Principal Investigator: R. Honrath

Sponsor: NSF

Funding Level: $295, 052

Period: 2005-2008
Abstract:

Despite its distance from the boreal regions, the Pico Mountain station (in the Azores Islands in the central North Atlantic) is frequently impacted during summer by plumes of aged emissions from boreal fires in Alaska, Canada, and even Siberia. Because they are made in the free troposphere, measurements at the Pico Mountain station have proven suitable for observing impacts of the upwind fires on ozone and ozone precursors. As a result of the long distance of the observatory from the fires responsible, these measurements are indicative of emissions and impacts over a large region. In this project, we are analyzing the database of prior Pico Mountain observations of CO, ozone, NOx, NOy and equivalent black carbon to deduce the magnitude of large-scale fire impacts and assess fire emissions. These analyses utilize FLEXPART transport simulations, conducted at Michigan Tech, MOZART GCTM simulations provided by G. Pfister at NCAR, Boreal Wildfire Emissions Model simulations provided by E. Hyer at NRL, and a variety of satellite products. So far, we have demonstrated that the Pico observations imply a rather large impact of boreal fires on ozone levels over a very large region (Lapina et al., 2006), and have deduced the presence of a significant seasonal trend in NOx:CO emission ratios in these fires, the result of an increase in the relative importance of smoldering fires as the fire season progresses (Lapina et al., in preparation).

Primary collaborations: Gabi Pfister, NCAR (MOZART simulations of transport and transformations of emissions from the 2004 North American boreal wildfires), Ed Hyer, NRL (Boreal Wildfire Emissions Model-based estimation of emissions from North American and Siberian boreal fires in 2004 and 2005.)