Enhanced transport in the polar mesosphere of Jupiter: Evidence from Cassini UVIS helium 584 Å airglow

The eddy diffusion profile (K) in the auroral regions of Jupiter is not well determined. However, because of the intense auroral energy input, eddy mixing is expected to be much more effective and may be responsible for the enhancement of heavy hydrocarbon production in the polar region. In this paper, we estimate the increased eddy mixing in the Jovian auroral regions by comparing the Cassini Ultraviolet Imaging Spectrograph (UVIS) observations during the 2000 Jupiter flyby with radiative transfer calculations of the He 584 Å airglow intensity. We derive a range for the eddy diffusion coefficients at the homopause (K_h) in the auroral regions to be at least 8 × 10^6 cm^2 s^(−1) and possibly greater than 4 × 10^7 cm^2 s^(−1). By comparison, equatorial K_h is on the order of 2 × 10^6 cm^2 s^(−1).