= = the 12-14 micron region lies outside the terrestrial atmospheric windows and can not be observed from the ground. the only information available in this spectral range was provided by the voyager infrared data acquired in 1980 with a spectral resolution of 4.3 cm-1 (0.096 micron). at this resolution and due to the high noise level of the infrared spectrometer (iris) aboard voyager, only mean mole fractions of the gases with emission signatures in the thermal infrared range could be obtained, with significant error bars. no information was obtained on the vertical distributions of these components, except for a 2-altitude-levels profile from a particular observing sequence over titan.s north pole. the profiles showed a general tendency for increase with height, implying formation of the species in the upper atmosphere (in accordance with photochemical models). in order to determine with precision the vertical distributions of c3h8 and c2h6, the iso/sws f-p capabilities are required in the 12-14 micron region where, within two short spectral intervals (around 748 and 821 cm-1), each molecule presents an emission band, with a strong q-branch and some multiplets. this part of the spectrum is also covered in the grating mode by the sws in the central programme at 0.5 cm-1, which does not permit to resolve the bands. the iso/sws f-p will allow us to determine with accuracy the molecular abundances of the two species, and to constrain current photochemical models, while providing information on the eddy mixing profile. at the same time we will combine these fp observations with sws grating scans in the 2.38 - 2.6 mu region, unexplored up to now, at no additional time cost.
Instrument
SWS07
Temporal Coverage
1997-06-20T08:40:19Z/1997-06-20T13:14:07Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
