F region plasma drifts over Arecibo: Solar cycle, seasonal, and magnetic activity effects

1993 ◽  
Vol 98 (A8) ◽  
pp. 13645-13652 ◽  
Author(s):  
B. G. Fejer
Keyword(s):  
Solar Cycle ◽  
Magnetic Activity ◽  
F Region ◽  
Plasma Drifts ◽  
Region Plasma

Solar cycle and seasonal variations in F-region vertical drifts over Kodaikanal, India

1995 ◽  
Vol 13 (6) ◽  
pp. 633-640 ◽  
Author(s):  
K. B. Ramesh ◽  
J. H. Sastri
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Seasonal Variations ◽  
Normal Incidence ◽  
Magnetic Activity ◽  
Solar Flux ◽  
Seasonal Trend ◽  
F Region ◽  
Phase Path ◽  
10.7 Cm Solar Flux

Abstract. Measurements of the changes in phase path of F-region reflections at normal incidence at Kodaikanal (77° 28'E, 10° 14'N, dip 3°N) from February 1991 to February 1993 are used to determine the variation of the equatorial evening F-region vertical drifts (V z) with season, solar and magnetic activity. It is found that on average, at Kodaikanal, the post-sunset peak in Vz(Vzp) is higher in equinox and local winter months than in local summer. The day-to-day variability in V zp is highest in summer and lowest in winter. This seasonal trend persists even on magnetically quiet days (Ap \\leq14). Vzp is found to increase with 10.7 cm solar flux in all three seasons but tends to saturate for large flux values (>230 units) during local summer and winter months. Magnetic activity [represented by Ap as well as the time-weighted accumulations of a p and ap (τ)] does not seem to have any statistically significant effect on Vzp , except during equinoctial months of moderate solar activity, when Vzp decreases as magnetic activity increases.

VHF and HF radar measurements of E and F region plasma drifts at the magnetic equator

1992 ◽  
Vol 97 (A3) ◽  
pp. 3011-3017 ◽  
Author(s):  
K. S. Viswanathan ◽  
S. P. Namboothiri ◽  
P. B. Rao
Keyword(s):  
Magnetic Equator ◽  
Hf Radar ◽  
F Region ◽  
Plasma Drifts ◽  
Radar Measurements ◽  
Region Plasma

Solar cycle effects on large scale equatorial F-region plasma depletions

1999 ◽  
Vol 24 (11) ◽  
pp. 1477-1480 ◽  
Author(s):  
Y. Sahai ◽  
P.R. Fagundes ◽  
J.A. Bittencourt
Keyword(s):  
Solar Cycle ◽  
Large Scale ◽  
F Region ◽  
Plasma Depletions ◽  
Region Plasma

Characteristics of VHF scintillations in the equatorial anomaly crest region in India

1995 ◽  
Vol 13 (7) ◽  
pp. 730-739 ◽  
Author(s):  
K. N. Pathak ◽  
R. D. Jivrajani ◽  
H. P. Joshi ◽  
K. N. Iyer
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Magnetic Activity ◽  
Summer Season ◽  
Equatorial Anomaly ◽  
Equatorial Station ◽  
F Region ◽  
Ionospheric Scintillations

Abstract. The characteristics of ionospheric scintillations at Rajkot in the equatorial anomaly crest region in India are described for the years 1987–1991 by monitoring the 244-MHz transmission from the satellite FLEETSAT. This period covers the ascending phase of solar cycle 22. Scintillations occur predominantly in the pre-midnight period during equinoxes and winter seasons and in the post-midnight period during summer season. During equinoxes and winter, scintillation occurrence increases with solar activity, whilst in summer it is found to decrease with solar activity. Statistically, scintillation occurrence is suppressed by magnetic activity. The characteristics observed during winter and equinoxes are similar to those seen at the equatorial station, Trivandrum. This, coupled with the nature of the post-sunset equatorial F-region drift and h'F variations, supports the view that at the anomaly crest station, scintillations are of equatorial origin during equinox and winter, whilst in summer they may be of mid-latitude type. The variations in scintillation intensity (in dB) with season and solar activity are also reported.

scholarly journals Average vertical and zonal F region plasma drifts over Jicamarca

1991 ◽  
Vol 96 (A8) ◽  
pp. 13901-13906 ◽  
Author(s):  
B. G. Fejer ◽  
E. R. de Paula ◽  
S. A. González ◽  
R. F. Woodman
Keyword(s):  
F Region ◽  
Plasma Drifts ◽  
Region Plasma

scholarly journals Radar and satellite investigations of equatorial evening vertical drifts and spread <i>F</i>

2015 ◽  
Vol 33 (11) ◽  
pp. 1403-1412 ◽  
Author(s):  
J. M. Smith ◽  
F. S. Rodrigues ◽  
E. R. de Paula
Keyword(s):  
Local Time ◽  
Empirical Model ◽  
Sufficient Condition ◽  
Satellite Measurements ◽  
Equatorial Spread F ◽  
Annual Variability ◽  
F Region ◽  
Plasma Drifts ◽  
Spread F ◽  
Coherent Backscatter

Abstract. We analyzed pre-midnight equatorial F region observations made by the 30 MHz coherent backscatter radar of São Luis, Brazil between August 2010 and February 2012. These measurements were processed, and used to create monthly maps of the echo occurrence as a function of local time and height. The maps show the inter-annual variability associated with equatorial spread F (ESF) occurrence in the Brazilian longitude sector. We also constructed monthly curves of the evening vertical drifts, for the Brazilian sector, using measurements by the ion velocity meter (IVM) onboard the C/NOFS satellite. The IVM evening drifts show a good overall agreement with the Scherliess and Fejer (1999) empirical model. Measured and model drifts show the development of the pre-reversal enhancement (PRE) of the vertical plasma drifts during ESF season. Using joint radar and satellite measurements, we found that evening (18:00–18:30 LT) mean non-negative drifts provide a necessary but not sufficient condition for the occurrence of topside ESF echoes. Evening downward (negative) drifts preceded the absence of topside ESF irregularities.

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