Global disturbance of the transient magnetic field associated with thermospheric storm winds on March 23, 1979

Fambitakoye, O.; Menvielle, M.; Mazaudier, Christine

doi:10.1029/ja095ia09p15209

Cited by 23 publications

(19 citation statements)

References 17 publications

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“…The actions of largescale current systems, such as those related to the magnetospheric convection and to the ionospheric disturbed dynamo, through storm winds in the low thermosphere (Richmond and Matsuchita, 1975;Blanc and Richmond, 1980;Mazaudier, 1985;Mazaudier et al, 1985), have been pointed out in middle and low latitudes. Fambitakoye et al (1990) have studied the magnetic eects of the ionospheric disturbed dynamo. Interactions between those current systems and the EEJ would be one of the causes of the EEJ day-to-day variability (Mayaud, 1982;Mazaudier, 1989).…”

Section: Resultsmentioning

confidence: 99%

Equatorial electrojet at African longitudes: first results from magnetic measurements

Doumouya

Vassal²,

Cohen³

et al. 1998

Ann Geophysicae

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Abstract. In the framework of the French participation in the International Equatorial Electrojet Year (IEEY), ten magnetotelluric stations were installed between November 1992 and November 1994 along a 1200-kmlong meridian pro®le, between Lamto (latitude 6.2°N, CoÃ te d'Ivoire) to the south and Tombouctou (latitude 16.7°N, Mali) to the north. These stations measured digitally the three components of the magnetic ®eld and the two components of the telluric electric ®eld, and operated over a period of 20 months. The magnetic data is used to study the features of the equatorial electrojet (EEJ) in West African longitude. The measurement of the telluric electric ®eld variations will be presented elsewhere. Hourly mean values are used to study the morphological structure of the regular diurnal variation S R of the three components (H, D, and Z) of the earth magnetic ®eld and to characterize the EEJ during magnetically quiet days. The occurrences of the counter-electrojet (CEJ) are set forth, emphasizing its seasonal variability. Assumed to be a current ribbon, the EEJ main parameters (the position of its center, its width, and the amplitude of its current density at the center) are determined. A preliminary analysis of the time variations of these parameters is presented over period of 20 months (from January 1993 to August 1994). Results are compared with those obtained during previous experiments of the same kind.

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Section: Resultsmentioning

confidence: 99%

Equatorial electrojet at African longitudes: first results from magnetic measurements

Doumouya

Vassal²,

Cohen³

et al. 1998

Ann Geophysicae

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“…[4] Richmond and Matshushita [1975] studied the thermospheric response to magnetic storms and later on, Blanc and Richmond [1980] first proposed the ionospheric disturbance dynamo to explain the electric field disturbance observed with the incoherent scatter sounder of Saint-Santin later after the end of storm and due to the dynamo action of storm winds generated by the auroral Joule heating [Blanc and Richmond, 1980;Fejer et al, 1983;Sastri, 1988;Fejer and Scherliess, 1995;Mazaudier and Venkateswaran, 1990;Fambitakoye et al, 1990;Fejer, 2002;Richmond et al, 2003].…”

Section: Ionospheric Disturbance Dynamomentioning

confidence: 99%

Magnetic signature of the ionospheric disturbance dynamo at equatorial latitudes: “D_dyn”

2005

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[1] During magnetic storms, wind disturbances produced by auroral phenomena can affect the whole thermospheric circulation and associated ionospheric dynamo currents for many hours after the end of the storms. In this paper we define criteria to select a new simple type of ionospheric disturbance dynamo events that allow a simple interpretation over all longitude sectors. These events exhibit a weak auroral activity during at least 24 UT hours, on the day after the storm. We analyze the magnetic disturbances ''D dyn '' observed at equatorial latitudes in the three longitude sectors of such selected events. It is found for all the cases that the amplitude of the H component of the Earth's magnetic field is reduced, on the day after storm at equatorial latitudes, in agreement with the ionospheric disturbance dynamo model (Blanc and Richmond, 1980). The observation of H component decrease on the day after storm is longitudinally asymmetric. The observed signature of the ionospheric disturbance dynamo process in a specific longitude sector is strongly dependent on the magnitude, the start time, and the duration of the storm.Citation: Le Huy, M., and C. Amory-Mazaudier (2005), Magnetic signature of the ionospheric disturbance dynamo at equatorial latitudes: ''D dyn '',

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“…Many theoretical and experimental work, during these last decades, dealt with the direct penetration of the magnetospheric convection electric field from the polar region towards the equatorial latitudes (Wolf, 1970;Pellat and Laval, 1972;Senior and Blanc, 1984;Mazaudier et al, 1984;Spiro et al, 1988;Kobea et al, 2000;. In 1980, Blanc and Richmond observed the electric field disturbance, after the end of a storm, due to the dynamo action of storm thermospheric winds generated by auroral Joule heating, during the active phases of the storm and first proposed the ionospheric disturbance dynamo mechanism to explain this phenomenon (Fejer et al, 1983;Sastri, 1988;Fambitakoye et al, 1990;Mazaudier and Venkateswaran, 1990;Fejer and Scherliess, 1995;Fejer, 2002). The limited number of studies related to the disturbance dynamo mechanism, from the time of the work of Blanc and Richmond (1980) to those of Le Huy and Amory- Mazaudier (2005), confirm the complexity of the attempt to isolate ionospheric disturbed dynamo events.…”

Section: Introductionmentioning

confidence: 99%

Latitudinal profile of the ionospheric disturbance dynamo magnetic signature: comparison with the DP2 magnetic disturbance

et al. 2009

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Abstract. During magnetic storms, the auroral electrojets intensification affects the thermospheric circulation on a global scale. This process which leads to electric field and current disturbance at middle and low latitudes, on the quiet day after the end of a storm, has been attributed to the ionospheric disturbance dynamo (Ddyn). The magnetic field disturbance observed as a result of this process is the reduction of the H component amplitude in the equatorial region which constitutes the main characteristic of the ionospheric disturbance dynamo process, associated with a westward electric current flow. The latitudinal profile of the Ddyn disturbance dynamo magnetic signature exhibits an eastward current at mid latitudes and a westward one at low latitudes with a substantial amplification at the magnetic equator. Such current flow reveals an "anti-Sq" system established between the mid latitudes and the equatorial region and opposes the normal Sq current vortex. However, the localization of the eastward current and consequently the position and the extent of the "anti-Sq" current vortex changes from one storm to another. Indeed, for a strong magnetic storm, the eastward current is well established at mid latitudes about 45 • N and for a weak magnetic storm, the eastward current is established toward the high latitudes (about 60 • N), near the Joule heating region, resulting in a large "anti-Sq" current cell. The latitudinal profile of the Ddyn disturbance as well as the magnetic disturbance DP2 generated by the mechanism of prompt penetration of the magnetospheric convection electric field in general, show a weak disturbance at the low latitudes with a substantial amplification at the magnetic equator. Due to the intensity of the storm, the magnitude of the DP2 appears higher than the Ddyn over the American and Asian sector contrary to the African sector.

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Global disturbance of the transient magnetic field associated with thermospheric storm winds on March 23, 1979

Cited by 23 publications

References 17 publications

Equatorial electrojet at African longitudes: first results from magnetic measurements

Equatorial electrojet at African longitudes: first results from magnetic measurements

Magnetic signature of the ionospheric disturbance dynamo at equatorial latitudes: “D_dyn”

Latitudinal profile of the ionospheric disturbance dynamo magnetic signature: comparison with the DP2 magnetic disturbance

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Global disturbance of the transient magnetic field associated with thermospheric storm winds on March 23, 1979

Cited by 23 publications

References 17 publications

Equatorial electrojet at African longitudes: first results from magnetic measurements

Equatorial electrojet at African longitudes: first results from magnetic measurements

Magnetic signature of the ionospheric disturbance dynamo at equatorial latitudes: “Ddyn”

Latitudinal profile of the ionospheric disturbance dynamo magnetic signature: comparison with the DP2 magnetic disturbance

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Magnetic signature of the ionospheric disturbance dynamo at equatorial latitudes: “D_dyn”