First in situ measurement of electric field fluctuations during strong spread F in the Indian zone
An RH-560 rocket flight was conducted from Sriharikota rocket range (SHAR) (14°N, 80°E, dip 14°N) along with other experiments, as a part of equatorial spread F (ESF) campaign, to study the nature of irregularities in electric field and electron density. The rocket was launched at 2130 local tim...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2000-05-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/18/523/2000/angeo-18-523-2000.pdf |
| Summary: | An RH-560 rocket flight was conducted from
Sriharikota rocket range (SHAR) (14°N, 80°E, dip 14°N) along with other
experiments, as a part of equatorial spread F (ESF) campaign, to study the
nature of irregularities in electric field and electron density. The rocket was
launched at 2130 local time (LT) and it attained an apogee of 348 km. Results of
vertical and horizontal electric field fluctuations are presented here. Scale
sizes of electric field fluctuations were measured in the vertical direction
only. Strong ESF irregularities were observed in three regions, viz., 160-190
km, 210-257 km and 290-330 km. Some of the valley region vertical electric field
irregularities (at 165 km and 168 km), in the intermediate-scale size range,
observed during this flight, show spectral peak at kilometer scales and can be
interpreted in terms of the image striation theory suggested by Vickrey <i>et
al.</i> The irregularities at 176 km do not exhibit any peak at kilometer scales
and appear to be of a new type. Scale sizes of vertical electric field
fluctuations showed a decrease with increasing altitude. The most prominent
scales were of the order of a few kilometers around 170 km and a few hundred
meters around 310 km. Spectra of intermediate-scale vertical electric field
fluctuations below the base of the F region (210-257 km) showed a tendency to
become slightly flatter (spectral index <i>n</i> = -2.1 ± 0.7) as compared to
the valley region (<i>n</i> = -3.6 ± 0.8) and the region below the F peak (<i>n</i>
= -2.8 ± 0.5). Correlation analysis of the electron density and vertical
electric field fluctuations suggests the presence of a sheared flow of current
in 160-330 km region.<br><br><b>Keywords: </b>Ionosphere (Electric fields and currents;
ionospheric irregularities); Radio science (ionospheric physics) |
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| ISSN: | 0992-7689 1432-0576 |