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|Title:||Electron densities in the equatorial lower ionosphere over Thumba and SHAR|
|Authors:||Sinha, H S S|
|Abstract:||The paper presents the structures of the electron density profiles and the associated irregularities up to about 150 km over Thumba, India (8°52´ N, 76°87´E, dip 0°47´S) and up to 340 km over SHAR, India (13°42´ N, 80°E, dip 14°N). These profiles were obtained using rocket-borne Langmuir probes and resonance probes. In all, profiles of 27 rocket flights conducted from Thumba and 6 from SHAR are presented. During the daytime normal electrojet (NEJ), the electron density profiles over Thumba were very smooth with only positive electron density gradients (i.e. the density profiles over Thumba were very smooth with only positive electron density gradients (i.e. the density increasing with increasing altitude). Increase in the density above 100 km altitude was much slower as compared to that below 100 km. During the daytime counter electrojet (CEJ), sharp layers of electron density, having a vertical extent of a few kilometers, were observed over Thumba. The nighttime profiles over Thumba show pronounced structures in the form of layers which are believed to be due to shears in the gravity wave winds. Morning and evening profiles over Thumba (around the twilight periods) show structures similar to the nighttime ones except that the peak densities are slightly smaller as compared to the nighttime values. The single daytime electron density profile available over SHAR during the NEJ period, shows the presence of a sharp layer around 90 km. The morning, evening and nighttime profiles over SHAR show a lot more structures as compared to the profiles over Thumba. These structures are believed to be due to the gravity waves.|
|ISSN:||0975-105X (Online); 0367-8393 (Print)|
|Appears in Collections:||IJRSP Vol.24(4) [August 1995]|
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