Determination of Joule Heating in the Auroral Ionosphere

A key component of the Sun-Earth Connections initiative is the quantification of the physics, dynamics and behavior of the Sun-Earth system over the 11-year solar cycle. The interaction of the solar wind with Earth's magnetosphere can result in the storage of large amounts of energy in the magnetospheric system. The subsequent release of this energy results in the energization of particles trapped in the magnetosphere and the acceleration into Earth's atmosphere causing the aurora. In addition, the ionosphere in the auroral zone is modified by the precipitating particles causing large variations in the height integrated conductivities and the flow of currents in the region. Global auroral image data from the Polar/Visible Imaging System (VIS) will be used to determine the instantaneous open polar cap magnetic flux. The time rate of change of this magnetic flux is the net result of magnetic merging in the solar wind-magnetosphere interaction region and of reconnection in the distant magnetic tail. The nighttime reconnection rate is small during periods of low auroral activity. For these times, the change in the total open magnetic flux of the polar cap is a direct measure of the rate of merging on the dayside. The Polar/VIS observations of total open magnetic flux of the polar cap in combination with static and dynamic pressures of the solar wind can be used to estimate the energy stored in the flaring magnetotail lobes. The HF radars of the Super Dual Auroral Radar Network (SuperDARN) will be used to determine in detail the geomagnetic flux transferred into and out of the polar cap. Height integrated conductivities derived from VIS auroral images are validated using data from the Sondrestrom and EISCAT incoherent scatter radars. The SuperDARN data combined with the height integrated auroral conductivities derived from the Polar/VIS auroral images will be used to derive the joule heating dissipation in the auroral ionosphere.