Analysis of the April 2002 Geomagnetic Storm Effect on Global CO2 Infrared Limb Emission as Observed by TIMED/SABER.

The SABER instrument on TIMED is continuously measuring limb radiance profiles of CO₂ ν ₃(4.3-μm) and \nu₂(15-μm) with unprecedented sensitivity. SABER provides limb radiances up to ~130km for the 15- μm channel and ~140-150km (approaching 200km during strong aurora) for the 4.3-μm channel. During the April 2002 geomagnetic storm the 4.3-μm band nighttime emission which also includes aurorally excited NO⁺(v) emission above about 100km responded dramatically. In the auroral region limb radiance was enhanced by more than a factor of 20 above the quiescent nighttime levels, at times being as bright as the daytime emission. The enhancement expanded equatorward as the storm effects intensified. However, the CO₂ 15-μm band was not significantly enhanced. We will examine the global behavior of the limb radiance, including other bands such as the O₂ ¹Δ_g 1.28-μm band and the 2.0-μm band, and TIMED GUVI EUV atomic oxygen and molecular nitrogen emissions, in an effort to distinguish direct auroral excitation from storm related temperature and composition changes.