Modeling of radio emissions from Neptune

We have developed a plasma model of the Neptunian magnetosphere that includes a density cavity centered on the L = 6 magnetic field line. Assuming the 08 magnetic field model, we have performed ray tracing of smooth radio emission from Neptune, and the results generally support the findings of Ladreiter et al. (1991), but differ in details of the source locations. In addition, we have examined source locations of bursty radio emission that are consistent with propagation at small wave normal angles as hypothesized for the temperature anisotropic beam instability (TABI) (Winglee et al., 1992). The source locations are adjacent (complementary) to the sources of the smooth radio emission. Using previously developed plasma and magnetic field models for Uranus, we have performed a similar study of bursty radio emissions. Again the source locations appear to be adjacent to the source regions of smooth radio emission, consistent with the TABI.