The role of low-frequency boundary waves in the dynamics of the dayside magnetopause and the inner magnetosphere
Tuesday, 2 September 2014: 3:15 PM
Regency Ballroom (Hyatt Regency)
Kyoung-Joo Hwang, NASA GSFC, Greenbelt, MD, United States; Goddard Planetary Heliophysics Institute - GPHI, University of Maryland, Baltimore County, Baltimore, MD, United States and David G Sibeck, NASA/GSFC, Greenbelt, MD, United States
Abstract:
Observational studies using data from multipoint spacecraft combined with ground magnetograms are presented to understand the role of the low-frequency waves commonly observed along the Earth's magnetopause and in the low-latitude boundary layer (LLBL) as an intermediary between solar-wind drivers and dayside and/or inner magnetospheric dynamics. Typical physical processes occurring at the magnetopause boundary layer include Kelvin-Helmholtz waves generated by shear flows and newly-identified LLBL velocity fluctuations, which both provide multiple paths to affect inner-magnetospheric particle density and energy fluxes. Ultra-Low-Frequency (ULF) waves detected by inner magnetospheric probes (such as the Van Allen Probes) and/or ground magnetometers are often excited by, or enhanced, during these boundary fluctuations. We present categorized case studies linking boundary fluctuations to variations of inner magnetospheric fields and plasmas and interplanetary drivers. In particular, we present a case study indicating that the magnetopause in the vicinity of a plasmaspheric plume is absolutely unstable to Kelvin-Helmholtz waves, resulting in a dawn-dusk asymmetry in the Earth's dayside magnetosphere.
