Vertical Plasma Drifts Estimated from Ionospheric F2-Region Real Heights at a Low Latitude Station during Low Solar Activity

Abstract

Vertical plasma drift velocities (v_z ) estimated from peak heights of F2-region (h_mF2) was investigated over Ilorin (lat. 8.31°N, long. 4.34°E, dip lat. 2.95^o N) during a year of Low Solar Activity (LSA), a station sited at the low latitudinal dip. The monthly means of vertical plasma drifts,  were estimated from 10-international quiet days (IQDs) monthly means of h_mF2 computed across each local time hour. Diurnally,  had behavourial patterns of pre-noon and post-noon peaks noticed for all seasons, but in h_mF2, it had pre-noon and post-sunset peaks occurred for all seasons. The  pre-noon peak magnitudes are 1.0, 2.4 and 6.4 m/s for December Solstice, June Solstice and Equinox respectively; and  post-noon peak magnitudes are 0.6, 1.7 and 2.2 m/s for December Solstice, Equinox and June Solstice respectively. The h_mF2 pre-noon peak magnitudes is from 316 to 353 km, and post-sunset peak magnitudes is from 310 to 392 km for all seasons. Also,  displayed pre-reversal enhancement (PRE) night peaks for all seasons. The PRE peak magnitudes are from -0.1 m/s to -1.2 m/s at 2000 LT, from -0.2 m/s to -4.0 m/s at 2200 LT, from -0.6 m/s to -3.0 m/s at 0000 LT and from -0.5 m/s to -1.8 m/s between 0300 LT and 0400 LT respectively for all seasons. The same phenomenal occurrence was noticed in the annual patterns of h_mF2 and . In general, the  and h_mF2 magnitudes were highest in equinox (6.4 m/s and 353 km) and lowest in solstice (1.0 m/s and 310 km). The  and h_mF2 steady and incessant drop shows the rapidly drifting away of electrons from the equator caused by solar ionization in the low latitude region for all seasons.