The occurrence, spatial distribution, and wave properties of hydrogen-, helium-, and oxygen-band EMIC waves observed by the Van Allen Probes

Wednesday, 17 December 2014: 11:06 AM
Anthony Saikin1, Jichun Zhang2, Robert Colby Allen3, Charles William Smith1, Lynn M Kistler1, Harlan E. Spence1, Roy B Torbert4, Craig Kletzing5 and Vania Jordanova6, (1)University of New Hampshire Main Campus, Durham, NH, United States, (2)University of New Hampshire, Durham, NH, United States, (3)University of Texas at San Antonio, San Antonio, TX, United States, (4)Univ New Hampshire, Durham, NH, United States, (5)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (6)Los Alamos National Laboratory, Los Alamos, NM, United States
Electromagnetic ion cyclotron (EMIC) waves play an important role in the overall dynamics of the Earth’s magnetosphere, including the energization and loss of particles. We perform a statistical study of EMIC waves detected by the Van Allen Probes mission to investigate their occurrence, spatial distribution, and properties (e.g., wave power, normal angle, and ellipticity). Magnetic field measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) onboard Van Allen Probes are used to identify EMIC wave events from the beginning of the mission (September, 2012) to the present. EMIC waves are examined in hydrogen, helium and oxygen bands. So far, about 280 EMIC wave events have been identified over the three different bands. Preliminary results show that hydrogen-band EMIC waves have been primarily observed in the dusk sector, while helium-band EMIC waves have been observed in all Magnetic Local Times (MLTs). Particularly, the Van Allen Probes provide a better resolution of lower frequencies (0.2-0.9 Hz), within which oxygen-band EMIC waves can occur in the inner magnetosphere. This allows us to obtain better insight into the characteristics of this previously largely unavailable band of EMIC waves, and allows for comparisons amongst EMIC waves in different bands.