Energetics of the mesosphere and lower thermosphere and the SABER experiment

Abstract

The energy budget of the mesosphere and lower thermosphere is governed by numerous sources and sinks of energy including radiative, chemical, and dynamical processes. The various radiative and chemical sources and sinks of energy, which occur far from local thermodynamic equilibrium (LTE), will be briefly reviewed in this paper. In addition, the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) Experiment, presently under development for the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) mission, will be introduced. SABER is an infrared emission limb sounder which will observe, at high radiometric accuracy, emissions from carbon dioxide (15 μm), ozone (9.6 μm), and nitric oxide (5.3 μm) to assess temperature, radiative cooling, and ozone abundances. SABER will also observe the singlet-delta molecular oxygen emission (1.27 μm), the Meinel bands of the hydroxyl radical (1.6 and 2.0 μm), water vapor (6.7 μm), and carbon dioxide emission at 4.3 μm. From these measurements a virtually complete computation of the radiative and chemical heating and radiative cooling rates in the mesosphere and lower thermosphere can be obtained.