Instruments on board the NOAA Polar-orbiting Operational Environmental Satellite (POES) continually monitor the power flux carried by the protons and electrons that produce aurora in the atmosphere. SWPC has developed a technique that uses the power flux observations obtained during a single pass of the satellite over a polar region (which takes about 25 minutes) to estimate the total power deposited in an entire polar region by these auroral particles. The power input estimate is converted to an auroral activity index that ranges from 1 to 10.
Over 100,000 satellite passes comprise the NOAA POES historical database that was used to construct statistical patterns of auroral power flux for each of the 10 levels of auroral activity as defined by total power dissipation as illustrated in the following table.
|Total Power Dissipation in Gigawatts||Activity Index||