Abstract: 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. SEC 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 Activity Index Kp Index
Gigawatts

4-6 3 1+
10-16 5 2+
24-39 7 3+
61-96 9 5-

http://sec.noaa.gov/pmap/Intro.html