Solar driven trends in the mesosphere and lower thermosphere as observed by SABER

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument has been observing the Earth's mesosphere and lower thermosphere continuously for 5.5 years, since January 2002. SABER observes infrared emission in 10 discrete spectral bands from 15.5 to 1.27-um. From these observations kinetic temperature, ozone, carbon dioxide, water vapor, volume emission rates (NO, O2, and OH), atomic species (H, O), rates of solar heating, rates of radiative cooling, and rates of exothermic chemical reactions are derived.

SABER has now observed for one-half of a solar cycle, primarily covering the transition from solar maximum to solar minimum. During this time the SEE instrument on the TIMED satellite and the SOLSTICE-B instrument on the SORCE satellite have been measuring the solar EUV radiation that reaches the thermosphere. These measurements show substantial changes over time in the solar irradiance (and then the energy absorbed by the thermosphere). In this paper we show that these changes can be strongly correlated with changes in the thermospheric cooling by both NO and CO2 derived from SABER measurements.

We will review the changes observed by SABER in this time period in the thermal structure, chemical composition, and radiative balance, and present comparisons with model calculations.