Jovian Stratospheric Hazes -- the View from Galileo

K. A. Rages (SPRI / NASA Ames), Galileo Imaging Team

During the E4 orbit in December 1996, Galileo obtained eight images of Jupiter's limb -- at latitudes of 8 tex2html_wrap_inline27 N and 60 tex2html_wrap_inline27 N, at phase angles of 146 tex2html_wrap_inline27 and 157 tex2html_wrap_inline27 , and in violet (407 nm) and NIR continuum (756 nm) filters. Stratospheric hazes are present at both latitudes. The hazes at 8 tex2html_wrap_inline27 N are more or less uniformly mixed with the gas, as are the hazes at 60 tex2html_wrap_inline27 N, 295 tex2html_wrap_inline27 W (the location probed at 157 tex2html_wrap_inline27 phase angle). However, a discrete haze layer is clearly visible above Jupiter's limb at 60 tex2html_wrap_inline27 N, 315 tex2html_wrap_inline27 W (the location probed at 146 tex2html_wrap_inline27 phase angle). The extinction coefficient of this discrete haze layer decreases by a factor of tex2html_wrap_inline49 between 407 nm and 756 nm, indicating that the mean particle size in this layer is tex2html_wrap_inline51 m. The discrete layer is at a pressure no higher than tex2html_wrap_inline53 mbar. The combined gas/haze single scattering phase function at the point where the atmosphere becomes optically thick (the ``main limb'') varies with latitude, and so far efforts to fit both the violet and NIR filters using a common haze particle size have failed, indicating a change in haze particle properties between the altitudes probed ( tex2html_wrap_inline55  mbar in violet and tex2html_wrap_inline57  mbar in NIR).