SUSHIL KUMAR
Articles written in Journal of Earth System Science
Volume 102 Issue 2 June 1993 pp 307-312
Some results of night-time scintillations at low latitude
Sushil Kumar S K Vijay A K Gwal
Ionospheric scintillation observations of VHF radio signals from FLEETSAT satellite (73°E longitude) at Bhopal from January 1990 to December 1990 have been used to study the characteristic variations of scintillation activity. It is found that scintillation occurrence is essentially a night-time phenomenon and day-time scintillations are very rare. Annual average nocturnal variation of percentage occurrence of scintillations shows maximum at around 2100–2200 hours LT. Seasonally, scintillations are most prominent during equinoxes and least during summer. Geomagnetic disturbances tend to decrease the occurrence of scintillations in the pre-midnight period.
Volume 130 All articles Published: 9 September 2021 Article ID 0186 Research article
PARVEEN KUMAR MONIKA SANDEEP SUSHIL KUMAR RICHA KUMARI DINESH KUMAR NARENDRA KUMAR
The frequency-dependent shear-wave quality factor (
$\bf{Highlights}$
$\bullet$ The frequency-dependent shear-wave quality factor and site amplification are computed simultaneously for the Garhwal region, NW Himalaya.
$\bullet$ A regional quality factor relationship of form, Qβ(f) = (102 ± 3.9)f(1.0±0.1) is established for the Garhwal Himalaya.
$\bullet$ The acceleration records corrected from the obtained site effect are used to develop attenuation relations at each recording station.
$\bullet$ The close resemblance of obtained Qβ(f) relations and the geology has been observed for the study region.
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