Daytime O/N2 Retrieval Algorithm for the Ionospheric Connection Explorer (ICON)

• Published in: Space science reviews Vol. 214; no. 1; pp. 1 - 17
• Main Authors: Stephan, Andrew W., Meier, R. R., England, Scott L., Mende, Stephen B., Frey, Harald U., Immel, Thomas J.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.02.2018; Springer Nature B.V
• Subjects: Aerospace Technology and Astronautics; Algorithms; Astrophysics and Astroparticles; Computer simulation; Daytime; Far ultraviolet radiation; Ionosphere; Mesosphere; Physics; Physics and Astronomy; Planetology; Retrieval; Satellites; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; The Ionospheric Connection Explorer (ICON) mission; Thermosphere; Thermospheric composition; ICON Explorer mission; Ultraviolet airglow; Thermosphere; Composition
• ISSN: 0038-6308; 1572-9672; 1572-9672
• DOI: 10.1007/s11214-018-0477-6

The NASA Ionospheric Connection Explorer Far-Ultraviolet spectrometer, ICON FUV, will measure altitude profiles of the daytime far-ultraviolet (FUV) OI 135.6 nm and N 2 Lyman-Birge-Hopfield (LBH) band emissions that are used to determine thermospheric density profiles and state parameters related to thermospheric composition; specifically the thermospheric column O/N 2 ratio (symbolized as Σ O/N 2 ). This paper describes the algorithm concept that has been adapted and updated from one previously applied with success to limb data from the Global Ultraviolet Imager (GUVI) on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission. We also describe the requirements that are imposed on the ICON FUV to measure Σ O/N 2 over any 500-km sample in daytime with a precision of better than 8.7%. We present results from orbit-simulation testing that demonstrates that the ICON FUV and our thermospheric composition retrieval algorithm can meet these requirements and provide the measurements necessary to address ICON science objectives.