New Organic Molecules from ACE-FTS Observations
Harrison, Jeremy1; Boone, Christopher2; Bernath, Peter3
1University of York, UNITED KINGDOM; 2University of Waterloo, CANADA; 3Old Dominion University, UNITED STATES
The Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS), onboard the SCISAT-1 satellite, is a high resolution (0.02 cm-1) instrument covering the 750-4400 cm-1 spectral region in solar occultation mode. ACE, an ESA third-party mission, was launched by NASA in August 2003 and the FTS performance remains excellent after almost 10 years in orbit. Although the primary mission goal is the study of ozone chemistry in the stratosphere, ACE continues to measure the vertical distribution of over 30 trace gases in the atmosphere, more than any other satellite instrument. The transmittance spectra, with high signal-to-noise ratios, are recorded through long atmospheric pathlengths (~300 km), providing a lower detection threshold for trace species in the atmosphere. A high inclination (74°) and low earth orbit (650 km) give ACE coverage of tropical, mid-latitude and polar regions.
Detecting trace molecules in the atmosphere is extremely important because they can contribute to air pollution and/or climate change, which produce negative effects on human health and ecosystems. For example, volatile organic compounds, which are released into the atmosphere from both natural and anthropogenic sources, are oxidised in the troposphere to produce ozone, a toxic and potent greenhouse gas. Profiles of new organic molecules continue to be retrieved from the entire catalogue of ACE spectra. This presentation will focus on some of the latest ACE 'research products', including acetonitrile, peroxyacetyl nitrate (PAN) and acetone. The acetonitrile measurements are the first infrared satellite remote-sensing observations for this molecule in the atmosphere and make use of new quantitative laboratory spectroscopic data.