Electron densities in the equatorial lower ionosphere over Thumba and SHAR

Abstract

The paper presents thirty electron density profiles obtained by rocket-borne Langmuir probe experiments conducted from Thumba, India (8°52′N, 76°87′E, dip 0°45′S). We consider for comparison six electron density profiles using the same technique from SHAR, India which is just outside the electrojet region. With the exception of two flights during counter electrojet (CEJ) condition, the Thumba flights correspond to daytime normal electrojet (NEJ) condition. The profiles over Thumba were very smooth, the electron density increased monotonously with increasing altitude. The increase above 100 km was much slower. Night, morning and eveningtime profiles over Thumba show pronounced structures. Most profiles show a maximum around 110 km and a valley around 130 km. For SHAR one daytime, two evening twilight and three nighttime profiles are presented. In general, the profiles over SHAR show a lot more structures as compared to Thumba profiles.