R G Rastogi
Articles written in Journal of Earth System Science
Volume 87 Issue 3 March 1978 pp 47-55
Radio beacon from ATS-6 at 140 MHz was used to measure the changes in the polarization angle (Faraday rotation) at Bombay, Rajkot, Ahmedabad, Udaipur and Patiala during October 1975 to July 1976. In this paper, results of diurnal, seasonal and latitudinal variations in total electron content (TEC) derived from these measurements are reported. The amplitude of diurnal peak is found to be higher at Rajkot, Ahmedabad and Udaipur as compared to that at Patiala or Bombay, indicating that the peak of Appleton anomaly in the latitudinal variation of TEC was close to the latitude of Ahmedabad. The diurnal maximum of TEC occurs around the same time during summer and winter months. The peak electron content shows a semiannual variation at all the stations with large values in equinoxes as compared to winter and summer. The TEC at Bombay shows a seasonal anamoly with high values in winter as compared to summer. The paper describes the development of latitudinal anomaly with the time of the day for different seasons. This anomaly is maximum during 1000 to 1800 LT and is located between 12° and 14° N (dip latitude) in summer and equinoxes and at about 10°N in winter.
Volume 87 Issue 3 March 1978 pp 57-60
It is shown that the storm sudden commencement (SSC) in
Volume 87 Issue 7 July 1978 pp 109-113
Geomagnetic disturbance effects on the occurrence of range and frequency spread at Huancayo are studied for the period 1957–74. The occurrence of frequency spread is decreased on disturbed days for
Volume 87 Issue 7 July 1978 pp 115-131
The post-sunset maximum in virtual height of the
Volume 87 Issue 7 July 1978 pp 147-153
The total electron content data obtained at Ahmedabad through the Faraday fading records of the radio beacons abroad the satellites Explorer 22 and 27 are used to determine the overhead integrated production rate (
Volume 87 Issue 7 July 1978 pp 173-178
Simultaneous observations of amplitude scintillations at 40 MHz, 140 MHz and 360 MHz radiated from ATS-6 satellite at 34° E longitude were made at Ootacamund near the magnetic equator in India. It has been found that the frequency variation of scintillation index (
Volume 87 Issue 11 November 1978 pp 215-224
Daily variations of the E-W and N-S components of ionospheric drifts, measured using closely spaced receiver method over Tiruchirapalli near magnetic equator, are described for the periods 1973–75 for
Volume 92 Issue 1 March 1983 pp 37-43
Almost saturated scintillations of radio beacons from geostationary satellites received at an equatorial station during night-time have been shown to occur even during complete absence of spread
Volume 93 Issue 2 July 1984 pp 83-89
Analysis of scintillations of
Volume 125 Issue 3 April 2016 pp 669-675
The geomagnetic storm of November 1998 is a unique event where IMF-Bz remained southward withvalues exceeding –15 nT for more than a day. The SYM/H index decreased from about 07 hr on 13November 1998 reaching a minimum of about –120 nT around midnight of 13–14 November 1998.Features of the equatorial electrojet in the Indian region are studied during the geomagnetic storm eventof 13–14 November 1998, based on the geomagnetic data from the chain of observatories in India. Suddennorthward turning of IMF-Bz for a very short duration around 08 hr on 13 November 1998 resultedin a small and very short duration counter electrojet. A strong (–50 nT) and a long duration counterelectrojet, right from 08 to 13 hr on 14 November 1998 was observed resulting in the absence of equatorialEs at Thumba. Absence of the equatorial ionization anomaly was also observed as seen from theionograms over Thumba and ionspheric data from Ahmedabad. The delayed effect on 14 November 1998is due to the disturbance dynamo effect.
Volume 126 Issue 4 June 2017 Article ID 0051
The effect of solar flare, sudden commencement of magnetic storm and of the disturbances ring current on the equatorial electrojet in the Eastern Brazil region, where the ground magnetic declination is as large as 20∘W is studied based on geomagnetic data with one minute resolution from Bacabal during November–December 1990. It is shown that the mean diurnal vector of the horizontal field was aligned along 2∘E of north at Huancayo and 30∘W of north at Bacabal during the month of December 1990. Number of solar flares that occurred on 30 December 1990 indicated the direction of solar flare related $\Delta H$ vector to be aligned along 5∘E of north at Huancayo and 28∘W of north at Bacabal. This is expected as the solar flare effects are due to the enhanced conductivity in the ionosphere. The SC at 2230 UT on 26 November 1990 produced a positive impulse in $\Delta X$ and negative impulse in $\Delta Y$ at Bacabal with $\Delta H$ vector aligned along 27∘W of north. At Huancayo the $\Delta H$ vector associated with SC is aligned along 8∘E of north, few degrees east to the alignment of the diurnal vector of H. The magnetic storm that followed the SC had a minimum Dst index of –150 nT. The corresponding storm time disturbance in $\Delta X$ at Huancayo as well as at Bacabal were about –250 nT but $\Delta Y$ at Bacabal was about +70 nT and very small at Huancayo, that give the alignment of the H vector due to ring current about 16∘W of north at Bacabal and almost along N–S at Huancayo. Thus alignment of the $\Delta H$ vector due to ring current at Bacabal is 14∘E of the mean direction of $\Delta H$ vector during December 1990. This is consistent with the direction of ring current dependent on the dipole declination at the ring current altitude which is about 5∘W of north over Bacabal and the deviation of declination due to the ring current during disturbed period given by the angle $(\psi-D)$.