Science commissioning of the atmospheric chemistry experiment (ACE)

Abstract

The Atmospheric Chemistry Experiment (ACE) was launched in August 2003 on board the Canadian scientific satellite SciSat-1. The ACE payload consists of two instruments: ACE-FTS, a high resolution (0.02 cm-1) Fourier transform infrared spectrometer and MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation), a dual UV-visible-NIR spectrograph. Primarily, the two instruments use a solar occultation technique to make measurements of trace gases, temperature, pressure and atmospheric extinction. It will also be possible to make near-nadir observations with the ACE instruments. The on-orbit commissioning of the instruments and spacecraft were undertaken in the months following launch. At the end of this period, a series of science-oriented commissioning activities were undertaken. These activities had two aims: the first was to verify and extend the measurement results obtained during the pre-launch Science Calibration Test campaign and the second was to confirm appropriate parameters and establish procedures for operational measurements (occultation and near-nadir observations and exo-atmospheric calibration measurements). One of the most important activities was to determine the relative location of each instrument field of view and optimize the pointing of the sun-tracker to provide the best viewing for both instruments.