Location
Yosemite National Park
Start Date
2-10-2014 10:20 AM
End Date
2-10-2014 10:50 AM
Description
At high latitudes plasma motions driven by the interaction of the magnetosphere with the solar wind are usually characterized in terms of an instantaneous distribution of the electrostatic potential. This potential distribution typically displays large-scale convection cells within which the direction and magnitude of the plasma flows are dependent on the solar wind speed and the solar wind magnetic field. Early observations show a remarkable consistency between the configuration of the electric potential, the associated current distributions that must accompany them and the auroral precipitation of energetic electrons, which carry a significant fraction of the current. Since the observational description of the convection, the current and the auroral precipitation, models of the solar wind magnetosphere interaction have been utilized to describe the associated interaction between the solar wind and the magnetosphere and the closure paths of the currents that flow through the ionosphere. In this way the drivers for the potential seen in the ionosphere and its dependence on solar wind conditions have been further understood. Still a point of discussion is the relative roles of so-called viscous interaction and merging in developing the ionospheric potential at different times. Currents in the ionosphere may originate from regions near the dayside magnetopause and from regions in the magnetospheric tail and these regions may not operate in unison. Thus, recent observations have focused on describing separately the spatial and temporal evolution of convection features on the dayside and the nightside. Changes in the magnetospheric drivers may be applied over small spatial and temporal scales but produce a more global reconfiguration of the major features of the convection pattern such as the convection reversal boundary and the low latitude extent of the auroral zone, which evolve on time scales of minutes to hours. How the plasma responds to these changes at different local times and latitudes is now being actively studied. Recent observations of ionospheric convection driven by the solar ind/magnetosphere interaction show that the volume over which this influence can be seen extends throughout the ionosphere to the magnetic equator. As the sphere of influence of the convection pattern changes significant changes in the plasma transport properties are produced with sometimes, dramatic changes in the plasma number density also appearing at a given location. In this brief review we will describe some key observations that illustrate the challenges associated with identifying the convection drivers, the ionospheric responses and the effects on the ionospheric plasma.
Ionospheric Convection at High Latitudes / Clips from Bill Hanson's 1974 presentation
Yosemite National Park
At high latitudes plasma motions driven by the interaction of the magnetosphere with the solar wind are usually characterized in terms of an instantaneous distribution of the electrostatic potential. This potential distribution typically displays large-scale convection cells within which the direction and magnitude of the plasma flows are dependent on the solar wind speed and the solar wind magnetic field. Early observations show a remarkable consistency between the configuration of the electric potential, the associated current distributions that must accompany them and the auroral precipitation of energetic electrons, which carry a significant fraction of the current. Since the observational description of the convection, the current and the auroral precipitation, models of the solar wind magnetosphere interaction have been utilized to describe the associated interaction between the solar wind and the magnetosphere and the closure paths of the currents that flow through the ionosphere. In this way the drivers for the potential seen in the ionosphere and its dependence on solar wind conditions have been further understood. Still a point of discussion is the relative roles of so-called viscous interaction and merging in developing the ionospheric potential at different times. Currents in the ionosphere may originate from regions near the dayside magnetopause and from regions in the magnetospheric tail and these regions may not operate in unison. Thus, recent observations have focused on describing separately the spatial and temporal evolution of convection features on the dayside and the nightside. Changes in the magnetospheric drivers may be applied over small spatial and temporal scales but produce a more global reconfiguration of the major features of the convection pattern such as the convection reversal boundary and the low latitude extent of the auroral zone, which evolve on time scales of minutes to hours. How the plasma responds to these changes at different local times and latitudes is now being actively studied. Recent observations of ionospheric convection driven by the solar ind/magnetosphere interaction show that the volume over which this influence can be seen extends throughout the ionosphere to the magnetic equator. As the sphere of influence of the convection pattern changes significant changes in the plasma transport properties are produced with sometimes, dramatic changes in the plasma number density also appearing at a given location. In this brief review we will describe some key observations that illustrate the challenges associated with identifying the convection drivers, the ionospheric responses and the effects on the ionospheric plasma.
Comments
The presentation was preceded by a viewing of Bill Hanson's 1974 presentation.
Roderick Heelis' presentation begins at 10:12