Evidence for Significant Local Generation of Plasmaspheric Hiss

Monday, 15 December 2014: 5:48 PM
Craig Kletzing1, William S Kurth1, Scott R Bounds1, George B Hospodarsky1, Ondrej Santolik2, John R Wygant3, John W Bonnell4, Yoshiharu Omura5 and Danny Summers6, (1)University of Iowa, Iowa City, IA, United States, (2)Academy of Sciences of the Czech Republic, Prague, Czech Republic, (3)University of Minnesota Twin Cities, Minneapolis, MN, United States, (4)University of California Berkeley, Berkeley, CA, United States, (5)RISH Research Institute for Sustainable Humanosphere, Kyoto, Japan, (6)Memorial University of Newfoundland, Dept of Math and Stats, St John's, Canada
The source of plasmaspheric hiss has been an outstanding problem in inner magnetospheric radiation belt physics since the discovery of this whistler-mode emission. The generation mechanism for plasmaspheric hiss has been suggested to come from one of three possible mechanisms: 1) local generation and amplification, 2) whistlers from lightning, and 3) chorus emissions which have refracted into the plasmasphere. The latter two mechanisms are external sources which produce an incoherent hiss signature as the original waves mix in a stochastic manner, propagating in both directions along the background magnetic field. In contrast, local generation of plasmaspheric hiss within the plasmasphere should produce a signature of waves propagating away from the source region. We report observations from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) Waves insturment on the Van Allen Probes that clearly indicate that the Poynting flux associated with plasmaspheric hiss is frequently propagating away from the equator in the outer region of the plasmasphere. Initial statistics suggest that for more than 40% of the orbits of the Van Allen Probes, the plasmaspheric hiss is generated by a local source within the plasmasphere. We present examples of the signature of locally generated plasmaspheric hiss and show additional statistics of locally generated hiss occurrence.