Fig. 4

Relations between the precipitating electron density (< 50 eV) and the mapped outflowing ion number flux in the SZA ranges of a 45°–85°, b 65°–105°, c 85°–125°, and d 105°–145°, and e comparisons among the derived empirical relations in these SZA ranges and the empirical formula derived by Strangeway et al. (2005) (their Eq. 3) (multiplied by a factor of 2.9 to correct for the altitudinal difference of the ion number flux and the precipitating electron density) (dotted gray line). The format is identical to that of Fig. 3. There are 3 data points below precipitating electron density of 3 × 10⁻³ cm⁻³. The precipitating electron densities and the mapped outflowing ion number fluxes of the 3 events are 8.39 × 10⁻⁵, 6.31 × 10⁻⁵, and 1.91 × 10⁻³ cm⁻³, and 5.76 × 10⁷, 1.93 × 10⁷, and 4.85 × 10⁷ cm⁻² s⁻¹ at SZA of 94.7°, 99.8°, and 142.9°, respectively