Anomalously low geomagnetic energy inputs during 2008 solar minimum

In this study, we examined the variation of the energy budget to the Earth's upper atmosphere during last solar cycle from both solar EUV irradiance and geomagnetic energy, including Joule heating and particle precipitation.

The globally integrated solar EUV power was calculated from the EUV flux model for aeronomic calculations (EUVAC) driven by the MgII index. The annal average of solar power in 2008 was 33 GW lower than that in 1996. The decrease of the globally integrated geomagnetic energy from 1996 to 2008 was close to 29 GW including 13 GW for Joule heating from Weimer (2005b) and 16 GW for particle precipitation from NOAA Polar-Orbiting Environmental Satellites (POES) measurements.