Airborne Observations of Ammonia in Aged Biomass Burning Plumes
Abstract
During the New England Air Quality Study - Intercontinental Transport and Chemical Transformation (NEAQS - ITCT) field program in 2004 the NOAA WP-3D aircraft sampled several aged forest fire plumes from Alaska and western Canada. These biomass burning plumes were identified by coincident enhancements in acetonitrile and carbon monoxide. Ammonia enhancements were observed in plumes on 4 flights using measurements from a chemical ionization mass spectrometer with 5s time resolution and an estimated uncertainty of +/- (25% + 100 pptv). The age of these plumes has been estimated at 8 to 12 days using the FLEXPART transport model. In most biomass burning plumes, ammonia mixing ratios ranged from 1 to 5 ppbv and was much greater than the average ammonia mixing ratio observed over the Northeastern United States of 0.29 ppbv. Typically, ammonia was correlated with carbon monoxide in these plumes with slopes ranging from 0.007 to 0.015 ppbv/ppbv and linear correlation coefficients ranging from 0.81 to 0.94. Some biomass burning plumes had been influenced by precipitation or cloud processing during transport as indicated by meteorological, aerosol, and volatile organic compound measurement. In these plumes ammonia was not enhanced and was uncorrelated with carbon monoxide indicating wet removal of ammonia. These observations suggest that biomass burning plumes lofted to the free troposphere can transport significant levels of ammonia multiple days downwind of the source if the plumes do not encounter precipitation or cloud processing during transport.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.A21C0149N
- Keywords:
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- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry;
- 0368 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: constituent transport and chemistry