Atmospheric Chemistry Experiment (ACE): spectroscopy from orbit

ACE (also known as SCISAT) is making a comprehensive set of simultaneous measurements of numerous trace gases, thin clouds, aerosols and temperature by solar occultation from a satellite in low earth orbit. A high inclination low earth orbit gives ACE coverage of tropical, mid-latitudes and polar regions. The primary instrument is a high-resolution infrared Fourier Transform Spectrometer (FTS) operating from 2 to 13 microns that measures the vertical distribution of trace gases, and the meteorological variables of temperature and pressure. Aerosols and clouds are being monitored using the extinction of solar radiation by two filtered imagers as well as by their infrared spectra. Although now in its eleventh year, the ACE-
FTS is still operating nominally. An introduction and overview of the ACE mission will be presented. Science results discussed will cover the free troposphere to the mesosphere, and will include the observation of organic molecules associated with air pollution, greenhouse gases (including CO2), halogen-containing gases, and polar mesospheric clouds.