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The assimilative mapping of ionospheric electrodynamics (AMIE) algorithm has been applied to derive the realistic time-dependent large-scale global distributions of the ionospheric convection and particle precipitation during a recent Geospace Environment Modeling (GEM) campaign period: March 28-29, 1992. The AMIE outputs are then used as the inputs of the National Center for Atmospheric Research thermosphere-ionosphere general circulation model to estimate the electrodynamic quantities in the ionosphere and thermosphere. It is found that the magnetospheric electromagnetic energy dissipated in the highlatitude ionosphere is mainly converted into Joule heating, with only a small fraction (6%) going to acceleration of thermospheric neutral winds. Our study also reveals that the thermospheric winds can have significant influence on the ionospheric electrodynamics. On the average for these 2 days, the neutral winds have approximately a 28% negative effect on Joule heating and approximately a 27% negative effect on field-aligned currents. The field-aligned currents driven by the neutral wind flow in the opposite direction to those driven by the plasma convection. On the average, the global electromagnetic energy input is about 4 times larger than the particle energy input• 1984; Potemra et al., 1984; Reiff and Burch, 1985; Lyons, 1985; Sojka et al., 1986; Heppner and Maynard, 1987]. The convecting ions in turn set the neutral gas into motion through ion drag. The neutral wind therefore tends to follow the ion convection [e.g., Hays et al., 1984; Killeen et al., 1984; McCormac et al., 1987]. On the other hand, the ionosphere is not totally passive in the determination of ion and neutral motions. It is now well known that the thermospheric winds can also produce dynamo effects that contribute to the overall electrodynamics of the coupled magnetosphereionosphere-thermosphere system [Paper number 95JA00766. 0148-0227 / 95 / 95J A-00766 $ 05.00 TIGCM) as well as its older version, the TGCM, have been widely used to investigate the thermospheric features for different periods of geophysical interest [e.g., Killeen and Roble, 1984; Lyons et al., 1985; Roble et al., 1987, 1988a; Forbes et al., 1987; Deng et al., 1991, 1993; Thayer and Vickrey, 1992]. All these studies have invoked empirical magnetospheric inputs of convection and particle precipitation to the models. Crowley et al. [1989] made the first effort to incorporate realistic time-dependent northern hemispheric convec-:•,. tion patterns derived from the assimilative mappihg of ionospheric electrodynamics (AMIE) procedure into the TGCM in their simulation of the thermosphefic response during the equinox transition study (ETS) interval of September 18-19, 1984. However, they adppted the empirical convection model of Heelis et al. [1.982] for the southern hemisphere and also made use of the particle precipitation inputs that were based on empirical auroral parameterization of Roble and Ridley [1987]. The focus of their study was thermospheric dynamics, that iS, the dist...

Solar variability is often cast in terms of radiative emission and the associated long-term climate response; however, growing societal reliance on technology is creating more interest in day-today solar variability. This variability is associated with both solar radiative and solar wind emissions. In this paper we explore the combined effects of radiative and solar wind fluctuations at Earth. The fluctuations in radiative and geomagnetic power create an extended interval of solar maximum for the upper atmosphere. We use a trio of empirical models to estimate, over the last three solar cycles, the relative contributions of solar extreme ultraviolet (UV) power, Joule power, and particle kinetic power to the Earth's upper atmosphere energy budget. Daily power values are derived from three source models. The SOLAR2000 solar irradiance specification model provides estimates of the daily extreme and far UV solar power input. Geomagnetic power is derived from a combination of satelliteestimated particle precipitation power and an empirical model of Joule power from hemispherically integrated estimates of high-latitude energy deposition. During the interval 1975 to 2003, the average daily contributions were: particles -36 GW, Joule -95 GW and solar -464 GW for a total of 595 GW. Solar wind-driven geomagnetic power provided 22% of the total global upper atmospheric energy. In the top 15 power events, geomagnetic power contributed two-thirds of the total power budget. In each of these events, Joule power alone exceeded solar power. With rising activity, Joule power becomes the most variable element of solar upper atmosphere interactions.

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