Thermospheric infrared radiance response to the April 2002 geomagnetic storm from SABER infrared and GUVI ultraviolet limb data

The SABER instrument on TIMED continuously measures certain infrared limb radiance profiles with unprecedented sensitivity. Among these are emissions of CO ₂ v ₃ at 4.3 μm, routinely recorded to tangent heights of ∼140-150 km, and NO at 5.3 μm, seen to above 200 km. Both of these are greatly enhanced during periods of strong auroral activity, when they can be measured to ∼200 km and ∼300 km, respectively. We use these infrared channels of SABER and coincident far ultraviolet (FUV) measurements from GUVI on TIMED, to study the geomagnetic storm of April 2002. These all give a consistent measure of auroral energy input into the lower thermosphere at high latitudes. Emission in yet another SABER channel, near 2.0 μm, correlates well with enhanced electron energy deposition. We also have, in the 5.3-μm emissions from the long-lived population of aurorally produced NO, a tracer of how this energy is transported equatorward and released over an extended period of time, a few days. In this paper, we discuss the global patterns of energy deposition into the expanded auroral oval, its transport to lower latitudes, and its loss as revealed by the NO 5.3-μm emissions.