High HONO concentrations in aged biomass burning plumes in NOMADSS campaign

Wednesday, 17 December 2014
Chunxiang Ye1, Xianliang Zhou1, Jochen Stutz2, James Festa2, Alex B Guenther3, Andrew John Weinheimer4, David J Knapp4, Teresa Lynn Campos5, Rebecca S Hornbrook4, Jorgen B Jensen6, Julia Haggerty5, Christopher A Cantrell7, Lee Mauldin7 and Lee Mauldin7, (1)Wadsworth Center, Albany, NY, United States, (2)University of California Los Angeles, Los Angeles, CA, United States, (3)Pacific Northwest National Laboratory, Richland, WA, United States, (4)NCAR, Boulder, CO, United States, (5)National Center for Atmospheric Research, Boulder, CO, United States, (6)NCAR Researc Aviation Facility, Broomfield, CO, United States, (7)Univ of Colorado, Boulder, CO, United States
More than a dozen of aged biomass burning plumes (BBPs) from various sources in free troposphere were encountered during the aircraft-based NOMADSS (Nitrogen, Oxidants, Mercury and Aerosol Distributions, Sources and Sinks) field campaign from June 1 to July 15, 2013. HCN and CO were used as tracers to identify the BBPs; the ratio of n-butane to propane was used to determine the photochemical age of the BBPs, which was ranging from 5 to 15 days. Significant enhancement in HONO concentration, by 5-56 ppt, was observed with elevated NOx and particulate nitrate concentrations in these BBPs comparing to background air mass. High HONO/NOx ratio up to 0.5 suppresses the importance of NOx as HONO precursors. Further HONO and NOx budget analysis reveals that photo-recycling of particulate nitrate in plumes to NOx was the main chemical source of NOx with HONO as an intermediate. An implication of this recycling NOx source on O3 formation is demonstrated in the correlation of O3 and NOx in aged plumes.