Abstract/Summary

In April 2011 Saturn’s midlatitude ionospheric H3+ emissions were detected, exhibiting anomalous (nonsolar) H3+ latitudinal variations consistent with the transport of water from specific locations in Saturn’s rings, known as “ring rain”. These products, transported to the planet along the magnetic field, may help to explain the unusual pattern of peaks and troughs in electron densities discovered in Saturn’s ionosphere by spacecraft flybys. In the present study, we analyzed H3+ emissions recorded on 23 April 2013, showing for the first time since the original detection that Saturn’s midlatitude H3+ emissions are indeed heavily modified. Although the 2013 emissions are dimmer by almost a factor of 3.7, the latitudinal contrast is greater and uncertainties are lower. Increased H3+ intensities were found near planetocentric latitudes of 43∘, 51∘, and 63∘, previously identified with sources at the inner edge of the B ring, A ring, and the orbit of Enceladus and associated E ring.