Hydrocarbons and condensible volatiles of Jupiter's Galileo probe entry site.

摘要

The Galileo Probe Mass Spectrometer (GPMS) dataset describes the composition of Jupiter's atmosphere between 0.43 and 22.3 bar in the probe entry site. The processing, calibration, and error analysis of the GPMS data is discussed, focusing on N2, the hydrocarbons CH4, C2H2, C2H4, C2H 6, C3H6, C3H8, C4H 4, C4H6, and C4H10, and the condensible volatiles (or CVs) H2O, NH3, and H 2S. These species are either difficult or impossible to measure via remote sensing, in the pressure interval sampled by the probe.; A one-dimensional photochemical model was implemented to study the production and transport of the hydrocarbons, with stratospheric ultraviolet methane photolysis as the source. Multiple vertical mixing cases did not produce agreement between the GPMS measurements and the photochemical model results, with possible explanations including a catastrophic tropopause-crossing mixing event, unknown hydrocarbon sources, and the need for further work with GPMS calibration and the photochemical model.; The probe descended into a 5-micron hotspot, a region characterized by low cloud opacity and depleted CVs. H2O, NH3, and H 2S all increased with depth, reaching their deep abundances in the order predicted by equilibrium cloud condensation models (ECCMs), but at deeper levels. GPMS water at 21 bar was still only 0.44 +/- 0.14 x solar, while GPMS H2S reached 2.16 +/- 0.65 x solar somewhere between 12 and 16 bar, and NH3 recovered to 3.6 +/- 0.5 x solar at about 8 bar, as inferred from the probe-to-orbiter signal attenuation. A one-dimensional entraining downdraft model was created to compare probe results to profiles produced by the descent of dry air as it mixes with the moist environment. Both the great depth of the water depletion and the inability of the entraining downdraft model to simultaneously replicate observed profiles of all three CVs imply that the downdraft descended into a region considerably drier and less stably-stratified than the ECCM scenario. This finding, along with the windshear in the probe site, are clues to the complexity of Jovian meteorology both inside and outside 5-micron hotspots.