Millimeter/submillimeter fourier transform spectroscopy of Jovian planet atmospheres

[摘要] A new Fourier transform spectrometer, built for use at the Caltech SubmillimeterObservatory, has been used to observe all four of the jovian planets (Jupiter,Saturn, Uranus, and Neptune) in the millimeter-submillimeter wavelength range (0.3-3.0 mm). The observations have resulted in the detection of the PH_3 1 - 0 rotationalline (266.9 GHz) in Saturn. and the PH_3 3 - 2 ( 800.5 GHz) line in both Jupiter andSaturn. Because PH_3 is a disequilibrium species, it is an important tracer of verticalmixing and upper atmospheric photochemistry, and can therefore be used to derivedynamical and chemical properties of the jovian atmospheres. A jovian planet radiative transfer code has been used to model the observed PH_3 lineshapes. Using theFTS, a spectral line survey covering the entire range of submillimeter frequencies observable from the ground has also been performed on Jupiter at Saturn at a resolutionof 200 MHz. This survey has yielded the tentative detection of HCl (and possiblyHCN) in Saturn and, again with the aid of radiative transfer modeling, provided agreat number of improved upper limits on the concentrations of many other species.Finally, Uranus and Neptune have been observed in the 1300 µm atmospheric windowwhich contains the CO 2 - 1 transition. This line was not detected in either planet,placing upper limits on the tropospheric CO mole fraction of 0.5 ppm in Uranus and1.4 ppm in Neptune.

[发布机构] University:California Institute of Technology;Department:Geological and Planetary Sciences

[关键词] Planetary Science and Physics