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Proceedings Paper

Advancements in understanding auroral ionosphere-thermosphere coupling from infrared remote sensing
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Paper Abstract

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.

Paper Details

Date Published: 16 September 2011
PDF: 10 pages
Proc. SPIE 8154, Infrared Remote Sensing and Instrumentation XIX, 815405 (16 September 2011); doi: 10.1117/12.895235
Show Author Affiliations
Christopher J. Mertens, NASA Langley Research Ctr. (United States)
Xiaojing Xu, SSAI, Inc. (United States)
Stanley J. Wellard, Utah State Univ. (United States)

Published in SPIE Proceedings Vol. 8154:
Infrared Remote Sensing and Instrumentation XIX
Marija Strojnik; Gonzalo Paez, Editor(s)

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