Sq currents in the American equatorial zone during the IGY—II Day to day variability

Hutton, Rosemary

doi:10.1016/0021-9169(67)90234-6

Cited by 26 publications

(3 citation statements)

References 13 publications

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“…The studies of the variability of the current centre and focus of the worldwide part of Sq (W Sq ) include those of Chapman & Bartels (1940), Hasegawa (1960), Matsushita (1960, 1967), Hutton (1967b), Schlapp (1976), Malin & Gupta (1977), Butcher & Brown (1980, 1981b), Butcher (1982b), Campbell (1989) and references therein, and Onwumechili et al . (1996).…”

Section: Introductionmentioning

confidence: 99%

Day-to-day variability of geomagnetic hourly amplitudes at low latitudes

Okeke

Onwumechili

Rabiu

1998

Geophysical Journal International

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A study of the variability of the amplitude of Sq at a fixed hour from one day to the next at nine stations from the dip equator to about 22° north of it has produced interesting results. The amplitude and sign of the variability change virtually randomly, making the mean practically zero. The variability occurs at all hours of the day. Its magnitudes in the components D, H and Z have the same diurnal variation, which peaks in the noon period like Sq(H) in low latitudes, and a weak seasonal variation that peaks at the June solstice (local summer). It is demonstrated that changes in the current intensities of the equatorial electrojet (EEJ) and the worldwide part of the Sq (W Sq) current layers have contrasting phases and can sometimes be in antiphase. Indeed, the changes are mostly independent. Inclusion of the magnetic element D revealed that the EEJ current system has not only an east–west but also a north–south component. The study shows that the meridional component of the EEJ current intensity evidenced at the Kodaikanal and Annamalainagar stations is an integral part of the zonal component at Trivandrum. This confirms the results of Rastogi (1996) and validates those of Onwumechili (1997). The results suggest that ionospheric conductivity mainly controls the magnitude, while the electric field and ultimately winds mainly control the phase and randomness of the day‐to‐day variability of the hourly amplitudes of Sq. The random component is attributed to local and/or regional atmospheric winds, probably of gravity wave origin.

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Section: Introductionmentioning

confidence: 99%

Day-to-day variability of geomagnetic hourly amplitudes at low latitudes

Okeke

Onwumechili

Rabiu

1998

Geophysical Journal International

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“…La figura 3 en Fukushima [3] muestra la variación magnética diaria en Koror para días quietos para las tres componentes del campo geomagnético, donde observamos que las variaciones diarias DD están invertidas en las estaciones del hemisferio de verano e invierno. La dependencia estacional de DD fue reportada por muchos investigadores [17,18,19,20]. Aunque el campo magnético en tierra de las CAC es considerablemente reducido en medianas latitudes magnéticas por las corrientes eléctricas de retorno que fluyen en la ionósfera, el efecto es perceptible en la región ecuatorial para CAC en bajas latitudes magnéticas a causa de un pequeño ángulo de inclinación observado o dip.…”

Section: Corrientes Eléctricas Alineadas Con El Campo Geomagnético En Bajas Latitudes Magnéticas En La Zona Ecuatorial Del Océanounclassified

Corrientes Eléctricas Alineadas con el Campo Geomagnético en Bajas Latitudes Magnéticas

1999

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La existencia de las corrientes eléctricas alineadas con el campo geomagnético en bajas latitudes magnéticas del Perú ha sido inferida utilizando los métodos de Gettemy[1] y Fukushima[2] aplicados a los datos magnéticos registrados durante el Año Geofísico Internacional (AGI) y el Año Internacional del Electrochorro Ecuatorial (AIEE) en el Perú. La representación de la variación magnética diaria quieta solar, Sq, usando mapas de contorno magnéticos de las componentes D, H y Z del campo geomagnético registrado en el Observatorio Magnético de Huancayo (OMH) para los dos periodos (1957-1958 y 1990-1991) permite visualizar los cambios estacionales en la variación diaria. Los resultados obtenidos son similares a los obtenidos por Gettemy para el Observatorio Magnético de Koror (OMK) en las Islas Palau (Océano Pacifico) durante el AGI. Los mapas de contorno magnéticos para las componentes D, H y Z del campo geomagnético registrado en el Observatorio Magnético de Ancón (OMA) para el periodo de 1990-1991 son también muy similares a los de Huancayo y Koror, aún en épocas diferentes. Asimismo, los mapas de contorno magnéticos para otras cinco estaciones magnéticas cerca al Ecuador magnético (1958) han sido elaborados para fines de comparación e interpretación. Dos diagramas, referidos a los patrones del sistema de corrientes eléctricas superiores de la variación magnética diaria quieta solar, Sq, para 1/2(verano + invierno) y 1/2(verano - invierno) en bajas latitudes magnéticas del Perú, fueron elaborados utilizando el método de análisis de las variaciones magnéticas diarias en tierra propuesto por Fukushima [2] para medianas latitudes geomagnéticas aplicado a cuatro estaciones magnéticas del Japón. Los resultados obtenidos nos permiten inferir las corrientes eléctricas alineadas con el campo geomagnético en bajas latitudes y confirmar la inversión estacional en la variación magnética diaria de la declinación en el OMH y en el OMA.

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“…The variation of Y showed a single minimum around noon at equatorial stations while at stations outside the electrojet belt AY was maximum during forenoon and minimum during afternoon hours. The daily variations of declination (or Y) at stations in the American sector showed a more complex variation during the daytime hours and has been explained due to the latitudinal shift of the boundary of northern and southern loops of the Sq current system with the time of the day (HUTTON, 1967).…”

Section: Introductionmentioning

confidence: 99%

Remarkable Solar Cycle and Seasonal Dependence of the Diurnal Geomagnetic D-Variations at Equatorial Electrojet Station, Kodaikanal.

Rastogi

1993

J. geomagn. geoelec

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Concurrent with the midday maximum of horizontal geomagnetic field, H, the eastward field Y at the equatorial electrojet station Kodaikanal shows a distinct minimum around noon during any of the years of solar cycle. The sunspot cycle variations of the daily variations of d Yare sympathetical with those of AH. Even the day to day fluctuations of the daily range Y are correlated with corresponding changes of H. Abnormal seasonal changes are seen in the daily variations of Y field at Kodaikanal as well as at other. observations in India. These significant daily variations of eastward field at Kodaikanal are suggested to be due to a systematic meridional current associated with the electrojet current.

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Sq currents in the American equatorial zone during the IGY—II Day to day variability

Cited by 26 publications

References 13 publications

Day-to-day variability of geomagnetic hourly amplitudes at low latitudes

Day-to-day variability of geomagnetic hourly amplitudes at low latitudes

Corrientes Eléctricas Alineadas con el Campo Geomagnético en Bajas Latitudes Magnéticas

Remarkable Solar Cycle and Seasonal Dependence of the Diurnal Geomagnetic D-Variations at Equatorial Electrojet Station, Kodaikanal.

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