Equatorial disturbance dynamo electric fields

Abstract

F‐region vertical drift data from Jicamarca, Peru show that equatorial east‐west electric fields are sometimes perturbed 16‐24 hours after the onset of geomagnetic storms. These disturbance dynamo electric fields, which must be caused primarily by the action of neutral winds at low and middle latitudes, decrease and sometimes even reverse the quiet time electric field pattern during both daytime and nighttime. The long delay excludes the possibility that gravity waves are responsible and suggests that the thermospheric circulation is disturbed. The data also show that after some storms there are no such delayed disturbances, a fact which may be due to the longitudinal structure of the disturbances at high latitudes and/or that only very strong storms can produce major thermospheric perturbations that extend to middle and low latitudes.

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

“…[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].…”

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

“…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.…”

Low-latitude ionospheric-thermospheric response to storm time electrodynamical coupling between high and low latitudes

“…[Blanc and Richmond, 1980;Fejer et al, 1983;Sastri, 1988;Mazaudier and Venkateswaran, 1990;Fejer, 1997]. Disturbance dynamo electric field is westward in dayside, i.e., opposite to the daytime ionospheric dynamo electric field and eastward in the nightside.…”