The OVATION (Oval Variation, Assessment, Tracking, Intensity, and Online Nowcasting) model is an empirical model of the intensity of an aurora developed at the Johns Hopkins University, Applied Physics Lab by Patrick Newell and co-workers.
The model uses solar wind and interplanetary magnetic field (IMF) conditions at the L1 point, upstream of Earth towards the sun, as inputs. The model produces an estimate of the intensity of the auroral energy at locations on Earth.
The OVATION Aurora Forecast Model shows the intensity and location of the aurora predicted. This probability forecast is based on current solar wind conditions measured at L1, but using a fixed 30-minute delay time between L1 and Earth. A 30-minute delay corresponds to approximately 800 km/s solar wind speed as might be encountered during geomagnetic storming conditions.
The sunlit side of Earth is indicated by the lighter blue of the ocean and the lighter color of the continents. The day-night line, or terminator, is shown as a region that goes from light to dark. The lighter edge is where the sun is just at the horizon. The darker edge is where the sun is 12 degrees below the horizon. Note that the aurora will not be visible during daylight hours; however, the aurora can often be observed within an hour before sunrise or after sunset. The red line at about 1000 km equatorward of the brightest aurora indicates how far away viewers on the ground might see the aurora assuming good viewing conditions.