Auroral Precipitation Models And Space Weather

The aurora is the projection screen of space weather, and auroral precipitation models represent a major portion of the former's impact on Earth's upper atmosphere. A precipitation model can be parameterized by solar wind driving, nowcast data from low-altitude satellites, or geomagnetic activity. We will show that each of these approaches serves significant and distinct roles. The quality of the predictions depends on the physical insights incorporated into the model organizing parameters. The use of solar wind driving to organize a model provides a closer link to the actual physical processes underlying solar wind-magnetosphere-ionosphere coupling, and is moreover needed for long-range forecasting. Nowcasting provides a "ground truth" and research tool that the other methods lack. However, we also show that in principle a properly organized model using the optimal geomagnetic indices-some of which are only currently becoming available from recent large-scale collaborations-has the greatest predictive ability, and by far the most promising path toward reconstructing detailed auroral patterns at high time cadence and with long-term continuity. For each method of constructing a precipitation model, the situations under which it is indicated are discussed, along with recent history and future logical directions for development.