Long-duration exohiss waves outside the plasmasphere: observed by Van Allen Probes

Thursday, 18 December 2014
Hui Zhu1, Zhenpeng Su1, Fuliang Xiao2, Huinan Zheng1, Yuming Wang1, Zhaoguo He3, Chao Shen4, Min Zhang1, Shui Wang1, Craig Kletzing5, William S Kurth5, George B Hospodarsky6, Harlan E. Spence7, Geoffrey D Reeves8, Herbert O Funsten9, J Bernard Blake10 and Daniel N. Baker11, (1)University of Science and Technology of China, Hefei, China, (2)Changsha University of Science and Technology, Changsha, China, (3)Organization Not Listed, Washington, DC, United States, (4)Chinese Academy of Sciences, Beijing, China, (5)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (6)Univ Iowa, Iowa City, IA, United States, (7)University of New Hampshire Main Campus, Durham, NH, United States, (8)Los Alamos National Laboratory, Los Alamos, NM, United States, (9)Los Alamos Natl Laboratory, Los Alamos, NM, United States, (10)The Aerospace Corp, Los Angeles, CA, United States, (11)University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States
We report an exohiss event in the low-density trough region observed by Van Allen Probes on 2 February 2014. These exohiss waves are discovered in the wide MLT distribution [9.1,13.4] and low magnetic latitude, with narrow-band structure and weak intensity compared with plasmaspheric hiss. Using the Continue Waveform Burst Mode data and MAG data on the EMFISIS, we analyze the normal angle, electromagnetic planarity and anti~/parallel-propagating Poynting flux of exohiss wave. The results show indicate that exohiss waves are the result of plasmaspheric hiss leakage into the trough region. The dependence of the proportion of anti~/parallel-propagating Poynting flux on MLT can be explained by Landau damping associated with suprathermal eletrons.