Reactive nitrogen distribution and partitioning in the North American troposphere and lowermost stratosphere

Abstract

A comprehensive group of reactive nitrogen species (NO, NO2, HNO3, HO2NO2, PANs, alkyl nitrates, and aerosol‐NO3−) were measured over North America during July/August 2004 from the NASA DC‐8 platform (0.1–12 km). Nitrogen containing tracers of biomass combustion (HCN and CH3CN) were also measured along with a host of other gaseous (CO, VOC, OVOC, halocarbon) and aerosol tracers. Clean background air as well as air with influences from biogenic emissions, anthropogenic pollution, biomass combustion, convection, lightning, and the stratosphere was sampled over the continental United States, the Atlantic, and the Pacific. The North American upper troposphere (UT) was found to be greatly influenced by both lightning NOx and surface pollution lofted via convection and contained elevated concentrations of PAN, ozone, hydrocarbons, and NOx. Observational data suggest that lightning was a far greater contributor to NOx in the UT than previously believed. PAN provided a dominant reservoir of reactive nitrogen in the UT while nitric acid dominated in the lower troposphere (LT). Peroxynitric acid (HO2NO2) was present in sizable concentrations peaking at around 8 km. Aerosol nitrate appeared to be mostly contained in large soil based particles in the LT. Plumes from Alaskan fires contained large amounts of PAN and aerosol nitrate but little enhancement in ozone. A comparison of observed data with simulations from four 3‐D models shows significant differences between observations and models as well as among models. We investigate the partitioning and interplay of the reactive nitrogen species within characteristic air masses and further examine their role in ozone formation.

Eta-CMAQ air quality forecasts for O<sub>3</sub> and related species using three different photochemical mechanisms (CB4, CB05, SAPRC-99): comparisons with measurements during the 2004 ICARTT study

“…There are consistent underestimations of NO x relative to both P3 and DC-8 observations (see Table 3 and Figs. 4 and 6) for all three mechanisms, being in agreement with Singh et al (2007). This is likely due to the fact that the aircraft and lightning NO emissions are not included in the current model emission inventory.…”

Airborne hydrogen cyanide measurements using a chemical ionisation mass spectrometer for the plume identification of biomass burning forest fires

“…In the upper troposphere lightning may well contribute an additional non-negligible source, and this region will be impacted by continental-scale plumes, evidenced by a variety of measurements (e.g. Liang et al, 2007;Singh et al, 2007;Park et al, 2008;Randel et al, 2010;Wiegele et al, 2012). These plumes will contain a mixture of potential sources of HCN, of which biomass burning may well be the most predominant.…”

Ground‐level nitrogen dioxide concentrations inferred from the satellite‐borne Ozone Monitoring Instrument

“…GEOS-Chem simulations generally agree to within 30% of measured NO x , HNO 3 , and PAN over eastern North America Hudman et al, 2007;Singh et al, 2007] [15] Figure 1 shows seasonal mean tropospheric NO 2 columns from OMI and GEOS-Chem. The high-resolution data in Figure 1 (first row) reveal relatively high values in many urban areas such as Los Angeles, San Francisco, Phoenix, Denver, Houston, Dallas, Chicago, Toronto, and the northeast U.S. corridor.…”