Electron temperature of Titan's sunlit ionosphere

Abstract

Titan's upper atmosphere is ionized by solar radiation and particle bombardment from Saturn's magnetosphere. The induced ionosphere plays a key role in the coupling of Titan's atmosphere with the Kronian environment. It also provides unique signatures for identifying energy sources upon Titan's upper atmosphere. Here we focus on observations from the first, close flyby by the Cassini spacecraft and assess the ionization and electron heating sources in Titan's sunlit ionosphere. We compare CAPS electron spectra with spectra produced by an electron transport model based on the INMS neutral densities and a MHD interaction model. In addition, we compare RPWS electron temperature against the models. The important terms in the electron energy equation include loss through excitation of vibrational states of N2 and CH 4, Coulomb collisions with suprathermal electrons, and thermal conduction. Our analysis highlights the important role of the magnetic field line configuration for aeronomic studies at Titan. Copyright 2006 by the American Geophysical Union.