Jupiter's Polar Haze
B.E. Carlson (NASA/GISS)
The nature and distribution of stratospheric aerosols in the polar regions of Jupiter are investigated using a combination of ground-based, Hubble Space Telescope (HST), and Voyager IRIS measurements. Of particular interest are the connections between the enhanced UV absorption in the polar regions and the bright polar hoods evident in methane band images and the connections between the aerosol, the infrared "hot spot", and the auroras.
Spatial maps of the hydrocarbon emissions constructed from the Voyager IRIS measurements reveal enhanced acetylene emission coincident with the region of enhanced methane emission but morphologically distinct from the region of enhanced ethane emission. This finding confirms the existence of altitude- dependent hydrocarbon chemistry. Ground-based and HST data reveal the presence of longitudinal structure in the latitudinal distribution of the aerosols (i.e., break-down in zonal symmetry) apparently associated with circulation anomalies induced by the polar hot spot. In addition, the HST data reveal a change in the aerosol properties (e.g., phase function) in the vicinity of the hot spot while ruling out changes in their height and/or optical depth distribution.
The HST data also reveal differential UV absorption coincident with the aurora
strengthening the connection between aerosol formation/hydrocarbon
chemistry and the aurora. The spectral dependence of this absorption suggests
enhancements of the higher order hydrocarbons (e.g., benzene). The
mismatch in spatial resolution between infrared (Voyager IRIS/ground-based
IRTF) and HST measurements coupled with the change in morphology of the
hot spot as revealed by the structure of the methane/acetylene emission versus
that of the ethane emission suggests the existence of more complex spatial
structure and additional thermal emission anomalies associated with auroral
processes unresolved by current infrared measurements