A Combined Solar and Geomagnetic Index for Thermospheric Climate

The climate of the thermosphere is controlled in part by cooling to space driven by infrared radiation from carbon dioxide (CO2, 15μm), nitric oxide (NO, 5.3μm), and atomic oxygen (O, 63μm). The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite has been measuring infrared cooling from CO2 and NO in the thermosphere since January 2002. These data provide integral constraints on the energy budget and climate of the atmosphere above 100 km.

Physically, changes in NO emission are due to changes in temperature, atomic oxygen, and the NO density. These physical changes, however, are driven by changes in solar irradiance and changes in geomagnetic conditions.