Event Title

F-Region Electric Fields from the St-Santin Multistatic Incoherent Scatter Facility

Location

Yosemite National Park

Start Date

2-7-1974 10:00 AM

End Date

2-7-1974 10:15 AM

Description

The French Incoherent Scatter facility was extended to a tristatic system in December 1972 and to a quadristatic one in October 1973. As each new receiver could supply data for one more component of the ion drift velocity, it became possible to measure first one component of the electric field and later the full electric field vector, in a plane perpendicular to the magnetic field. The conjugate sunrise behaviour of the electric field appears to be of particular interest. Indeed, the location of the French observatory is such that during the winter solstice the time difference between conjugate and local sunrise reaches a maximum of 4 hours thus allowing for an easy separation of the two effects. Under such conditions the occurrence of conjugate sunrise is characterized by a rapid change of the electric field correlated with the appearance of the phenomenon of spread F on the ionograms. These observations are discussed in the light of the theoretical work of H. C. Carlson and J. C. G. Walker on the electrodynamic drift in the nocturnal F region caused by a rapid change in the electrical conductivity of the conjugate ionosphere at the time of sunrise. The day time electric fields have a magnitude which is compatible with what is expected from either the dynamo or the magnetospheric electric field current theoretical calculations.

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Feb 7th, 10:00 AM Feb 7th, 10:15 AM

F-Region Electric Fields from the St-Santin Multistatic Incoherent Scatter Facility

Yosemite National Park

The French Incoherent Scatter facility was extended to a tristatic system in December 1972 and to a quadristatic one in October 1973. As each new receiver could supply data for one more component of the ion drift velocity, it became possible to measure first one component of the electric field and later the full electric field vector, in a plane perpendicular to the magnetic field. The conjugate sunrise behaviour of the electric field appears to be of particular interest. Indeed, the location of the French observatory is such that during the winter solstice the time difference between conjugate and local sunrise reaches a maximum of 4 hours thus allowing for an easy separation of the two effects. Under such conditions the occurrence of conjugate sunrise is characterized by a rapid change of the electric field correlated with the appearance of the phenomenon of spread F on the ionograms. These observations are discussed in the light of the theoretical work of H. C. Carlson and J. C. G. Walker on the electrodynamic drift in the nocturnal F region caused by a rapid change in the electrical conductivity of the conjugate ionosphere at the time of sunrise. The day time electric fields have a magnitude which is compatible with what is expected from either the dynamo or the magnetospheric electric field current theoretical calculations.