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  • Propagation of Chorus Waves...
    Kang, Ning; Bortnik, Jacob; An, Xin; Claudepierre, Seth G.

    Geophysical research letters, 28 December 2021, Letnik: 48, Številka: 24
    Journal Article

    We present the first ray tracing results of chorus waves generated in minimum‐B pockets. A new ray tracer is developed to accommodate an arbitrary magnetic field model, which enables us to construct minimum‐B pocket geometries using the Tsyganenko (1989) model. Rays with different frequencies and initial wave normal angles are launched from minimum‐B pockets and traced under different geomagnetic activity and hot electron density conditions. Our results indicate that chorus waves generated from minimum‐B pockets are usually highly localized and thus are unlikely to be detected unless the spacecraft is very close to the source region. These waves are also very unlikely to propagate into the plasmasphere. The propagation distances generally decrease with increasing geomagnetic activity. Plain Language Summary Chorus waves are an important kind of electromagnetic waves in the near‐Earth environment. We trace the ray paths of chorus waves generated in regions of low magnetic field intensity in the high‐latitude dayside magnetosphere (referred to as minimum‐B pockets) using a newly developed ray tracer which can deal with more complex geomagnetic field than the simplest model of magnetic field produced by a dipole magnet. Rays are launched with a range of frequencies, initial wave normal angles and space weather conditions. Our results indicate that chorus waves generated from minimum‐B pockets are usually highly localized and thus are very unlikely to be detected unless the spacecraft is very close to the source region. They are also very unlikely to propagate into the plasmasphere. The propagation distances in general decrease with enhanced geomagnetic activity. Key Points Ray tracing under a minimum‐B pocket geometry for chorus waves is conducted Under average hot electron condition, MBPG chorus waves get damped within 1 or 2 Re of distance and thus are highly localized Even when the hot electron proportion is only several ten thousands, MBPG chorus waves are very unlikely to propagate into the plasmapause