ULF wave energy transfer from the equatorial plane to the ionosphere: frequency and spatial dependence
Tuesday, 2 September 2014
Regency Ballroom (Hyatt Regency)
Michael Hartinger1, Mark B Moldwin1, Shasha Zou1, John W Bonnell2 and Vassilis Angelopoulos3, (1)University of Michigan, Ann Arbor, MI, United States, (2)Univ California, Berkeley, CA, United States, (3)UCLA---ESS/IGPP, Los Angeles, CA, United States
Abstract:
Ultra Low Frequency (ULF) waves transfer energy in the Earth's magnetosphere through a variety of mechanisms that impact the Earth's ionosphere, radiation belts, and other plasma populations. Using THEMIS satellite data, we examine the time averaged electromagnetic energy transfer rate, S(f), as a function of frequency (3-30 mHz) and region of the magnetosphere. We examine radial energy transport near the equatorial plane and compare observations with idealized global simulations of energy transport associated with specific ULF wave modes. From the observations, we find S(f) tends to be field-aligned near the magnetic equatorial plane, suggesting that the ionosphere is an important sink of wave energy. We map S(f) from the equatorial plane to the ionosphere, finding typical energy dissipation rates of 0.001-1 mW/m2, with most energy transferred at low frequencies and high-latitudes in the dayside post-noon sector. Generally, ULF waves transfer less energy than large scale, static currents (e.g., Region 2), but they can make substantial contributions to Joule heating and aurora in regions far from these current systems.
