Proceedings Article | 17 September 2011
Proc. SPIE. 8154, Infrared Remote Sensing and Instrumentation XIX
KEYWORDS: Infrared sensors, Satellites, Remote sensing, Chemistry, Solids, Spectral resolution, Information technology, Infrared radiation, Radiometry, Thermosphere
Recent discoveries from analysis of measurements made by the Sounding of the Atmosphere
using Broadband Emission Radiometry (SABER) instrument on the Thermosphere-Ionosphere-
Mesosphere Energetics and Dynamics (TIMED) satellite have shown that NO(v) 5.3 um
emission is the primary mechanism of dissipating solar-geomagnetic storm energy in the
thermosphere. Further insight into the ionosphere-thermosphere (IT) storm-time response
emerged from observations and analysis of the SABER 4.3 um channel radiances, which showed
that nighttime 4.3 um emission is dominated by NO+(v) during geomagnetically disturbed
conditions. Analysis of SABER NO+(v) 4.3 um emission led to major advances in the
understanding of E-region ion-neutral chemistry and kinetics, such as the identification of a new
source of auroral 4.3 um emission, which also provides a new context for understanding auroral
infrared emission from O2(a1▵g). Surprisingly, NO+(v) 4.3 um emission is the second largest
contribution to solar-geomagnetic infrared radiative response and provides a non-negligible
contribution to the "natural thermostat" thought to be solely due to NO(v) 5.3 um emission.
Despite these major advances, a fully physics-based understanding of the two largest sources of
storm-time energy dissipation in the IT system from NO(v) and NO+(v) is lacking because of the
limited information content contained in SABER's broadband infrared channel measurements.
On the other hand, detailed information on the chemical-radiative excitation and loss processes
for NO(v), NO+(v), and O2(a1▵g) emission is encoded in the infrared spectrum, of which SABER
only provides an integral constraint. Consequently, a prototype infrared field-wide Michelson
interferometer (FWMI) is currently under development to advance the understanding of IT
storm-time energetics beyond the current state of knowledge. It is anticipated that progress in the
developments of the FWMI technology, along with advancements in a physics-based
understanding of the fundamental chemical-radiative mechanisms responsible for IT infrared
emission, will play an integral role in the future planning of a rocket-borne and satellite-based Eregion
science missions. In this paper, a survey of recent SABER discoveries in IT ion-neutral
coupling will be given, open questions in a physics-based understanding of chemical-radiative
vibration-rotation excitation and loss from important IT infrared emitters will be identified, and
the FWMI instrument requirements necessary to address these open science questions will be
presented.
