Measurements of H2O in Jupiter's Atmosphere from 5 Microns Airborne Observations

Measurement of the abundance and vertical distribution of H2O in Jupiter's atmosphere is discussed. Water was first detected using the Kuiper airborne observatory (KAO) and has also been observed at 5 micrometers by the Voyager infrared spectrometer, IRIS. Studies of H2O in the atmospheres of other planets require special high altitude facilities to reduce the interference of telluric H2O. Jovian H2O absorption lines are overwhelmed by terrestrial H2O at ground-based observatories but they are readily apparent in airborne spectra. Typical column abundances of H2O above ground-based telescopes are about 3000 precipitable micrometers versus only 10 pr micrometers above the KAO at the 12.5 km level. For comparison, there is about 150 pr micrometers H2O above the 3 bar level on Jupiter. Airborne observations also take advantage of cryogenic detectors which have not been used thus far on deep space probes.