scholarly journals Observations of midlatitude ionospheric instabilities generating meter-scale waves at the magnetic equator

2009 ◽  
Vol 114 (A1) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. J. Makela ◽  
M. C. Kelley ◽  
R. T. Tsunoda
Keyword(s):  
Magnetic Equator

scholarly journals A study of atmospheric gravity waves and travelling ionospheric disturbances at equatorial latitudes

1997 ◽  
Vol 15 (8) ◽  
pp. 1048-1056 ◽  
Author(s):  
R. L. Balthazor ◽  
R. J. Moffett
Keyword(s):  
Gravity Waves ◽  
Large Scale ◽  
Ionospheric Disturbance ◽  
Magnetic Equator ◽  
Ionospheric Disturbances ◽  
Atmospheric Gravity Waves ◽  
Opposite Hemisphere ◽  
Travelling Ionospheric Disturbances ◽  
F Region ◽  
Atmospheric Gravity

Abstract. A global coupled thermosphere-ionosphere-plasmasphere model is used to simulate a family of large-scale imperfectly ducted atmospheric gravity waves (AGWs) and associated travelling ionospheric disturbances (TIDs) originating at conjugate magnetic latitudes in the north and south auroral zones and subsequently propagating meridionally to equatorial latitudes. A 'fast' dominant mode and two slower modes are identified. We find that, at the magnetic equator, all the clearly identified modes of AGW interfere constructively and pass through to the opposite hemisphere with unchanged velocity. At F-region altitudes the 'fast' AGW has the largest amplitude, and when northward propagating and southward propagating modes interfere at the equator, the TID (as parameterised by the fractional change in the electron density at the F2 peak) increases in magnitude at the equator. The amplitude of the TID at the magnetic equator is increased compared to mid-latitudes in both upper and lower F-regions with a larger increase in the upper F-region. The ionospheric disturbance at the equator persists in the upper F-region for about 1 hour and in the lower F-region for 2.5 hours after the AGWs first interfere, and it is suggested that this is due to enhancements of the TID by slower AGW modes arriving later at the magnetic equator. The complex effects of the interplays of the TIDs generated in the equatorial plasmasphere are analysed by examining neutral and ion winds predicted by the model, and are demonstrated to be consequences of the forcing of the plasmasphere along the magnetic field lines by the neutral air pressure wave.

scholarly journals Small-scale (∼3 m)Eregion irregularities at and off the magnetic equator

1998 ◽  
Vol 103 (A9) ◽  
pp. 20761-20773 ◽  
Author(s):  
B. V. Krishna Murthy ◽  
Sudha Ravindran ◽  
K. S. Viswanathan ◽  
K. S. V. Subbarao ◽  
A. K. Patra ◽  
...  
Keyword(s):  
Magnetic Equator ◽  
Small Scale

Initial orientation of homing pigeons at the magnetic equator with and without sun compass

1983 ◽  
Vol 14 (1) ◽  
pp. 77-79 ◽  
Author(s):  
R. Ranvaud ◽  
K. Schmidt-Koenig ◽  
J. Kiepenheuer ◽  
O. C. Gasparotto
Keyword(s):  
Initial Orientation ◽  
Magnetic Equator ◽  
Sun Compass ◽  
Homing Pigeons

scholarly journals The Guará Campaign: A series of rocket-radar investigations of the Earth's upper atmosphere at the magnetic equator

1997 ◽  
Vol 24 (13) ◽  
pp. 1663-1666 ◽  
Author(s):  
R. F. Pfaff ◽  
J. H. A. Sobral ◽  
M. A. Abdu ◽  
W. E. Swartz ◽  
J. W. LaBelle ◽  
...  
Keyword(s):  
Magnetic Equator ◽  
Upper Atmosphere

3. On the Lunar Diurnal Variation of Magnetic Declination at Trevandrum, near the Magnetic Equator

1872 ◽  
Vol 7 ◽  
pp. 756-758
Author(s):  
J. A. Broun
Keyword(s):  
Diurnal Variation ◽  
Diurnal Variations ◽  
Magnetic Equator ◽  
Magnetic Declination ◽  
The Law ◽  
The Times

The author gives the results derived from different discussions of nearly eighty thousand observations, made hourly during the eleven years 1854 to 1864. They are as follows:—1. That the lunar diurnal variation consists of a double maximum and minimum in each month of the year.2. That in December and January the maxima occur near the times of the moon's upper and lower passages of the meridian; while in June and July they occur six hours later, the minima then occurring near the times of the two passages.3. The change of the law for December and January to that for June and July does not happen, as in the case of the solar diurnal variations, by leaps in the course of a month (those of March and October), but more or less gradually for the different maxima and minima.

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