Intercomparison of Simultaneously Obtained Infrared (4.8 μm) and Visible (515−715 nm) Ozone Spectra Using ACE-FTS and MAESTRO

The ACE-MAESTRO instrument on SCISAT: description, performance, and preliminary results

The Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO) instrument on the SCISAT satellite is a simple, compact spectrophotometer for the measurement of atmospheric extinction, ozone, nitrogen dioxide, and other trace gases in the stratosphere and upper troposphere as part of the Atmospheric Chemistry Experiment (ACE) mission. We provide an overview of the instrument from requirements to realization, including optical design, prelaunch and on-orbit performance, and a preliminary examination of retrievals of ozone and NO(2).

Simultaneous measurements of visible (400-700 nm) and infrared (3.4 microm) NO(2) absorption

Laboratory measurements of NO(2) absorption were obtained in the visible (400-700 nm) and mid-infrared (3.4 mum) regions simultaneously using SCISAT-1's ACE-FTS (atmospheric chemistry experiment-Fourier transform spectrometer) and MAESTRO (measurement of aerosol extinction in the stratosphere and troposphere retrieved by occultation) spectrometers. An intercomparison of these measurements was used to verify the consistency between the HITRAN 2004 3.4-mum band strengths and the strengths of three different visible cross section data sets. These measurements should be of interest to the remote-sensing community, since NO(2) measurements obtained by infrared-range instruments are often compared to those obtained by visible-range instruments without accurate knowledge of the consistency between the visible and infrared absorption coefficients. Two significant results were obtained in this study: (1) A 0.5% agreement was found between the HITRAN 2004 line strengths and the Vandaele et al. (Vandaele, A. C.; Hermans, C.; Fally, S.; Carleer, M.; Colin, R.; Mérienne, M.-F.; Jenouvrier, A.; Coquart, B. J. Geophys. Res. 2002, 107 (D18), 4348) temperature-corrected cross sections, and (2) the mean pressure-broadened half-width of NO(2) by NO in the 3.4-mum band was measured as being 0.096 +/- 0.001 cm(-1) atm(-1). The latter finding is thought to be unreported by the literature.