Nadir measurements of the Earth's atmosphere with the ACE FTS: first results

Abstract. The primary objective of the Canadian SCISAT mission is to investigate the processes that control the distribution of ozone in the stratosphere. The SCISAT satellite consists of two major science instruments: an Atmospheric Chemistry Experiment (ACE) high-resolution Fourier-transform spectrometer (FTS) and an ultraviolet/visible/near-infrared spectrograph. These instruments primarily function in occultation mode; however, during the dark portion of the orbit the Earth passes between the sun and the satellite. This configuration provides the opportunity to acquire some nadir-view FTIR spectra of the Earth. Nadir spectra obtained with the ACE FTS are presented and analyzed for methane, ozone and nitrous oxide. The measurements show that the instrument should have sufficient signal-to-noise ratio to determine column gas amounts of the major trace constituents in the atmosphere. Possible applications of these measurements to the study of global warming and air pollution monitoring are discussed.