Abstract. Peroxyacyl nitrate (PAN) is a critical atmospheric reservoir for
nitrogen oxide radicals, and plays a lead role in their redistribution in
the troposphere. We analyze new Tropospheric Emission Spectrometer (TES) PAN
observations over North America from July 2006 to July 2009. Using aircraft
observations from the Colorado Front Range, we demonstrate that TES can be
sensitive to elevated PAN in the boundary layer (∼ 750 hPa) even in
the presence of clouds. In situ observations have shown that wildfire
emissions can rapidly produce PAN, and PAN decomposition is an important
component of ozone production in smoke plumes. We identify smoke-impacted TES
PAN retrievals by co-location with NOAA Hazard Mapping System (HMS) smoke
plumes. Depending on the year, 15–32 % of cases where elevated PAN is
identified in TES observations (retrievals with degrees of freedom (DOF) > 0.6)
overlap smoke plumes during July. Of all the retrievals attempted in the
July 2006 to July 2009 study period, 18 % is associated with smoke . A case
study of smoke transport in July 2007 illustrates that PAN enhancements
associated with HMS smoke plumes can be connected to fire complexes,
providing evidence that TES is sufficiently sensitive to measure elevated PAN
several days downwind of major fires. Using a subset of retrievals with TES
510 hPa carbon monoxide (CO) > 150 ppbv, and multiple estimates
of background PAN, we calculate enhancement ratios for tropospheric average
PAN relative to CO in smoke-impacted retrievals. Most of the TES-based
enhancement ratios fall within the range calculated from in situ
measurements.