Parameterization of Observed Saturn Z-Mode Wave Power for r < 4Rs

Tuesday, 16 December 2014: 4:12 PM
John Douglas Menietti1, Shengyi Ye1, Terrance F Averkamp1, Richard Bertram Horne2, Yuri Shprits3, Emma E Woodfield4 and Donald A Gurnett5, (1)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (2)NERC British Antarctic Survey, Cambridge, United Kingdom, (3)Massachusetts Institute of Technology, Cambridge, MA, United States, (4)British Antarctic Survey, Cambridge, United Kingdom, (5)Univ Iowa, Iowa City, IA, United States
Recent work has shown that z-mode/electron wave-particle interactions can lead to electron acceleration in the Saturn magnetosphere. These electrons may then form a partial source of Saturn's radiation belt which peaks in the range ~2Rs < r ~4Rs. The wave acceleration process depends on the local plasma density and on the distribution of z-mode wave power in frequency and spatial coordinates. In this study we bin the z-mode wave power observed by the Cassini radio and plasma wave science (RPWS) investigation in the region r < 4Rs at Saturn, where the condition fp/fc < 1 can be met (fp = plasma freq., fc = cyclotron freq.). The spatial bins include L-shell (based on a magnetic field model), latitude, and local time. Within each spatial bin we calculate the mean power-versus-frequency profile relative to fc, which can then be analytically fit. One goal of the study is to provide a database for use in quasilinear models requiring the calculation of pitch angle and momentum diffusion coefficients. In this report we present our initial findings.