Premium
Latitudinal Dependence of Daytime Electron Density Bite‐Out in the Ionospheric F 2 ‐Layer
Author(s) -
Chen Yiding,
Liu Libo,
Le Huijun,
Zhang Hui
Publication year - 2021
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja028277
Subject(s) - daytime , atmospheric sciences , latitude , crest , ionosphere , morning , diurnal temperature variation , ionosonde , f region , low latitude , environmental science , equator , electron density , geology , physics , plasma , geophysics , geodesy , astronomy , quantum mechanics
Daytime bite‐out in diurnal variations of the F 2 ‐layer electron density often occurs in the equatorial ionosphere, while it was less reported at mid‐latitudes. In this paper, the climatology of daytime bite‐out was investigated using ionosonde measurements in the East Asia sector. The bite‐out can take place at both low‐ and mid‐latitudes and mainly in summer months; and it significantly depends on latitudes. The bite‐out appears as f o F 2 stays stable or slightly decreases for hours in early morning and then enhances till late afternoon at equatorial ionization anomaly (EIA) crest latitudes. It becomes more significant and durative at mid‐latitudes; f o F 2 increases and reaches a peak in the morning and then continuously declines till afternoon. In particular, the diurnal variation pattern of f o F 2 is nearly opposite to that of photoionization at the higher‐latitude station Yakutsk at solar maximum. Moreover, the bite‐out is more remarkable at solar minimum (maximum) than at solar maximum (minimum) at low‐latitudes (mid‐latitudes). The trans‐equator plasma outflow caused by neutral winds and the upward thermal diffusion can result in the bite‐out in the EIA crest region, while the subsequent field‐aligned plasma influx induced by the fountain effect ceases it. At mid‐latitudes, the diurnal variation magnitudes of the thermospheric composition and photoionization production rate are also important factors determining bite‐out degree in addition to neutral wind‐induced downward transport and the upward thermal diffusion.