Abstract
AbstractUtilizing the DEMETER observations at 670 km, we examined the day‐night difference of energetic electrons (100–800 keV) in the South Atlantic Anomaly (SAA) region and their dependence on geomagnetic activities in different seasons. Under geomagnetically quiet conditions, the fluxes of higher‐energy electrons (>200 keV) in the dusk and midnight (MLT ~ 19–24 hr) are usually larger than those in the morning (MLT ~ 8–12 hr) in the core region of the SAA (−50 ≤ λ ≤ − 20deg) during the northern and southern summers (21 March 2007 to 23 September 2007 and 23 September 2007 to 21 March 2008). The day‐night difference of energetic electrons in SAA region depends not only on the electron energy but also on the geomagnetic activity levels. Enhanced geomagnetic activities increase the energetic electrons in morning and hence weaken their day‐night difference in the SAA region.
Highlights
South Atlantic Anomaly (SAA) leads to particular disturbances in space environments over the Earth
Utilizing the DEMETER observations at 670 km, we examined the day‐night difference of energetic electrons (100–800 keV) in the South Atlantic Anomaly (SAA) region and their dependence on geomagnetic activities in different seasons
Satellite observations indicate that the density of cold plasmas in the nighttime is much less than the daytime in the SAA region (Horvath & Lovell, 2009; Li et al, 2011)
Summary
South Atlantic Anomaly (SAA) leads to particular disturbances in space environments over the Earth. In the SAA region, the remarkable decrease in geomagnetic field allows the trapped high‐energy protons and electrons in the inner radiation belt to bounce to lower altitudes and generate radiation hazards to the spacecrafts and astronauts in low Earth orbits (Baker et al, 2018; Heirtzler, 2002; Ye et al, 2017; Zou et al, 2011, 2015). There are dense neutral atmospheric compositions and cold plasmas in the SAA region at ionospheric altitudes (
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