Formation of the Potential Jump over the Geomagnetically Quiet Sunlit Polar Cap Region

[摘要] We consider the formation of a potential drop over the Earth's polar cap during geomagnetically quiet daytime. The observed potential drop is primarily defined by the hydrogen, photoelectron, and polar rain fluxes ratios and depends strongly on the energy distribution of the photoelectron flux. Polar rain is an essential component of the model required for plasma quasineutrality. The potential distribution along the magnetic field line has two regions, with a small, gradual, potential drop of 3 to 4 volts and a potential jump. The value of the potential jump depends on the hydrogen ion to photoelectron flux ratio and is also controlled by polar rain electrons. With quasineutrality required at its upper boundary, the jump only occurs in the presence of polar rain and its location depends on the polar rain flux. Model predictions compare well with FAST (Fast Auroral SnapshoT) observations presented by Kitamura et al.(2012, https://doi.org/10.1029/2011JA017459).

[发布日期] 2019-05-24

[学科分类] 地质物理学

[关键词] GEOMAGNETISM;ELECTRON PRECIPITATION;ELECTRIC POTENTIAL;FLUX (RATE);POLAR CAPS;PHOTOELECTRONS;HYDROGEN IONS;AURORAS;MAGNETIC FIELDS;IONOSPHERIC DISTURBANCES;POLAR SUBSTORMS;EARTH MAGNETOSPHERE;SOLAR ACTIVITY EFFECTS