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 duringgeomagnetically 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 thephotoelectron 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, potentialdrop of 3–4 V and a potential jump. The value of the potential jump depends on the hydrogen ion tophotoelectron flux ratio and is also controlled by polar rain electrons. With quasineutrality required at itsupper boundary, the jump only occurs in the presence of polar rain and its location depends on the polarrain flux. Model predictions compare well with FAST observations presented by Kitamura et al.(2012, https://doi.org/10.1029/2011JA017459).

[发布日期] 2019-06-27

[学科分类] 大气科学

[关键词] BOUNDARIES;DAYTIME;ELECTRONS;FLUX (RATE);GEOMAGNETISM;HYDROGEN IONS;POLAR CAPS;RAIN