Nadir, limb, and occultation measurements with SCIAMACHY Original Research Article

The Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) is a contribution to the ENVISAT-1 satellite, which is to be launched in mid 2001. The SCIAMACHY instrument is designed to measure sunlight transmitted, reflected and scattered by the Earthʹs atmosphere or surface simultaneously from the UV to the NIR spectral spectral region (240 – 2380 nm) in various viewing geometries. Inversion of the SCIAMACHY measurements will provide the amount and distributions of a large number of atmospheric constituents in the stratosphere and troposphere (O3, NO2, H2O, CO2, CH4, N2O, BrO, CO, O2, O2(1Δg), NO, SO2, H2CO, (ClO,) and OClO). This paper concentrates on the characteristics of the SCIAMACHY mission. In particular, the measurement strategies for the different observational modes — nadir, limb, and both solar and lunar occultation — and their operational implementation are described.