28 May 2017 to 2 June 2017
Queen's University
America/Toronto timezone
Welcome to the 2017 CAP Congress! / Bienvenue au congrès de l'ACP 2017!

ACE-FTS satellite measurements of HCN in the upper troposphere to N2O in the lower thermosphere

30 May 2017, 16:00
BioSci 1120 (Queen's University)

BioSci 1120

Queen's University

Invited Speaker / Conférencier invité Atmospheric and Space Physics / Physique atmosphérique et de l'espace (DASP-DPAE) T4-6 DASP General Contributions I (DASP) | DPAE: contributions générales I (DPAE)


Patrick Sheese (University of Toronto)


Two recent discoveries from the Canadian ACE-FTS (Atmospheric Chemistry Experiment – Fourier Transfer Spectrometer) satellite instrument will be discussed. The first is the production of N2O in the lower thermosphere, and the second is a global enhancement of HCN in the upper troposphere – lower stratosphere throughout 2016. ACE-FTS has the only available satellite measurements of vertically resolved HCN in the upper troposphere - lower stratosphere and N2O in the lower thermosphere.
The N2O measurements show that there is a consistent lower thermospheric source of N2O via energetic particle precipitation (EPP). This leads to average polar winter concentrations on the order of ~20-40 ppbv near 90 km. In the polar winter, N2O-rich air descends into the lower mesosphere, and especially during sudden stratospheric warmings ACE-FTS observes N2O being transported as far down as ~45 km.
In late 2015, a large amount of HCN was emitted from Southeast Asia into the upper troposphere and lower stratosphere. The emitted HCN was then transported by the general circulation from the tropics to polar latitudes. By early 2016, the daily mean concentrations of HCN in the lower stratosphere at all latitudes, as measured by the ACE-FTS instrument, were consistently the largest on record for the region, on the order of 50-90% greater than the climatological mean, and ~30% greater than the 2007 El Niño-driven values.

Primary author

Patrick Sheese (University of Toronto)


Prof. Kaley Walker (University of Toronto) Prof. Peter Bernath (Old Dominion University) Dr Chris Boone (University of Waterloo)

Presentation Materials