Hydrogen cyanide in the upper troposphere: GEM-AQ simulation and comparison with ACE-FTS observations

Abstract

Abstract. We investigate the spatial and temporal distribution of hydrogen cyanide (HCN) in the upper troposphere through numerical simulations and comparison with observations from a space-based instrument.

Trends and variations in CO, C<sub>2</sub>H<sub>6</sub>, and HCN in the Southern Hemisphere point to the declining anthropogenic emissions of CO and C<sub>2</sub>H<sub>6</sub>

“…The global annual biomass-burning emis- sions of HCN vary between 1.45 and 3.43 Tg (HCN) yr −1 . These numbers are similar to those given by Li et al (2000) and Lupu et al (2009). Other sources (e.g.…”

Seasonal and interannual variations in HCN amounts in the upper troposphere and lower stratosphere observed by MIPAS

“…In contrast to MIPAS observations, in this region the ACE-FTS distribution is dominated by measurements from January, when the plume is already considerably weaker than in December. HCN climatologies derived from ACE-FTS measurements have already been published by Lupu et al (2009), Randel et al (2010 and Park et al (2013). As a more quantitative intercomparison, Fig.…”

“…The spectral regions used for ACE-FTS HCN retrievals are 1395-1460 and 3260-3355 cm −1 (Lupu et al, 2009), while for MIPAS retrievals microwindows between 729.5 and 776.95 cm −1 were applied. Since the spectroscopic uncertainties of the strongest HCN lines in each of these spectral regions listed in the HITRAN database (Rothman et al, 2013) are 5-10 % both for intensity and pressure broadening, they can lead to a systematic bias of up to 20 %.…”

“…These observations led to the conclusion that biomass burning is a major source of atmospheric HCN and that there must be an additional sink of tropospheric HCN. Today, HCN is considered as an almost unambiguous tracer of biomass burning Singh et al, 2003;Yokelson et al, 2007;Lupu et al, 2009). HCN has been used as tracer of biomass burning by, for example, Glatthor et al (2009) and Tereszchuk et al (2013).…”

“…Spaceborne observations of global HCN have been performed by the Fourier transform spectrometer of the Atmospheric Chemistry Experiment (ACE-FTS) on SCISAT Boone et al, 2005;Rinsland et al, 2005) and, generally restricted to the middle atmosphere, by the Microwave Limb Sounder (MLS) on the Aura satellite (Pumphrey et al, 2006). Climatologies of the HCN distribution derived from ACE-FTS measurements have been presented by Lupu et al (2009), Randel et al (2010) and Park et al (2013).…”