Laboratory procedure for simulating nadir measurements with the ACE-FTS

The Atmospheric Chemistry Experiment (ACE), or SCISAT mission, is a Canadian science satellite designed to investigate the chemical and dynamical processes that control the distribution of ozone in the stratosphere and upper troposphere. The ACE mission payload consists of two science instruments: a high-resolution infrared Fourier-Transform Spectrometer (FTS) and an ultraviolet/visible/near-infrared spectrometer. These instruments primarily function in occultation mode. However, during the dark portion of the orbit, the Earth passes between the Sun and the satellite. In this configuration, the ACE-FTS has the opportunity to acquire some nadir-view spectra of the Earth. Since the ACE-FTS was designed to view a hot source (i.e., the Sun) at high resolution using a single scan, it was necessary to determine if the ACE-FTS could also provide nadir spectra of the relatively cold atmosphere and surface with sufficient signal-to-noise ratio (SNR). As part of the pre-launch test program, laboratory measurements ...