Climatology of extreme upper atmospheric heating events

We use a trio of empirical models to estimate the relative contributions of solar extreme ultraviolet heating, Joule heating and particle heating to the global energy budget of the earth’s upper atmosphere. Daily power values are derived from the models for the three heat sources. The SOLAR2000 solar irradiance specification model provides estimates of the daily extreme EUV solar power input. Geomagnetic power comes from a combination of satellite-derived electron precipitation power and an empirical model of Joule power derived from hemispherically integrated estimates of high-latitude heating, which we discuss in this paper. From 1975 to mid-2002, the average daily contributions were electrons: 51 GW, Joule: 95 GW and solar: 784 GW. Joule and particle heating combine to provide more than 17% of the total global upper atmospheric heating. For the top 10% and 1% of heating events, contributions rise to ∼20% and 25%, respectively. In the top 15 heating events, geomagnetic power contributed more than 50% of the total power budget. During three events, the Joule power alone exceeded solar power.