References of "Stephan, A. W"
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See detailThe Production of Titan's Ultraviolet Nitrogen Airglow
Stevens, Michael H.; Gustin, Jacques ULg; Ajello, J. M. et al

in AAS/Division for Planetary Sciences Meeting Abstracts #42 (2010, October 01)

The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan's dayside limb on 22 June, 2009, obtaining high quality extreme ultraviolet (EUV) and far ultraviolet (FUV) spectra from a distance of ... [more ▼]

The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan's dayside limb on 22 June, 2009, obtaining high quality extreme ultraviolet (EUV) and far ultraviolet (FUV) spectra from a distance of only 60,000 km (23 Titan radii). The observations reveal the same EUV and FUV emissions arising from photoelectron excitation and photofragmentation of molecular nitrogen (N[SUB]2[/SUB]) on Earth but with the altitude of peak emission much higher on Titan near 1000 km altitude. In the EUV, emission bands from the photoelectron excited N[SUB]2[/SUB] Carroll-Yoshino c[SUB]4[/SUB]'-X system and N I and N II multiplets arising from photofragmentation of N[SUB]2[/SUB] dominate, with no detectable c[SUB]4[/SUB]'(0,0) emission near 958 Å, contrary to many interpretations of the lower resolution Voyager 1 Ultraviolet Spectrometer data. The FUV is dominated by emission bands from the N[SUB]2[/SUB] Lyman-Birge-Hopfield a-X system and additional N I multiplets. We also identify several N[SUB]2[/SUB] Vegard-Kaplan A-X bands between 1500-1900 Å, two of which are located near 1561 and 1657 Å where C I multiplets were previously identified from a separate UVIS disk observation. We compare these limb emissions to predictions from a terrestrial airglow model adapted to Titan that uses a solar spectrum appropriate for these June, 2009 observations. Volume production rates and limb radiances are calculated, including extinction by methane and allowance for multiple scattering within the readily excited c[SUB]4[/SUB]'(0,v') system, and compared to UVIS observations. We find that for these airglow data only emissions arising from processes involving N[SUB]2[/SUB] are present. [less ▲]

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See detailNeutral Ion Coupling Explorer satellite measurements of thermospheric composition, winds and temperatures.
Mende, S. B.; Immel, T. J.; England, S. et al

Conference (2008, December 01)

A new Small Explorer mission, the Neutral Ion Coupling Explorer (NICE) mission, was selected for study by NASA to specifically address neutral ion coupling in the Earth's atmosphere. The main goal of NICE ... [more ▼]

A new Small Explorer mission, the Neutral Ion Coupling Explorer (NICE) mission, was selected for study by NASA to specifically address neutral ion coupling in the Earth's atmosphere. The main goal of NICE is to study neutral-ion coupling at low latitudes where the densest plasma in geospace is created and where a number of remarkable interactions between the plasma and neutral gas occur even in the relative absence of high-latitude forcing. NICE will study this region from a ~24 degree inclination 550 km circular orbit, residing entirely on closed magnetic field lines. The relatively fast precession of low-inclination orbit is favorable for frequent sampling of all local times for the determination of tidal structures. It is now widely recognized that the neutral thermosphere has a strong influence on the ionosphere and that Earth's ionosphere at quiet times is actually tidally dominated. The NICE concept is unique in simultaneously providing measurements of the parameters relevant to ion production and motion across the entire altitude range of the low-latitude ionosphere. The science payload consists of 3 remote sensing instruments viewing the atmospheric limb (1) a dual Doppler Fabry-Perot Interferometer (FP), scanning in altitude to measure neutral wind vector and temperature altitude profiles in the E- and F-regions, (2) a Far Ultraviolet (FUV) imager to measure daytime neutral composition and image the nighttime F-layer intensity distributions, and (3) an Extreme Ultraviolet (EUV) altitude profiler to retrieve daytime F-layer properties. In addition, an Ion Velocity Meter (IVM) measures the in-situ ion drifts. NICE will take advantage of an elegant choice of orbit and instrument viewing geometries to make coordinated and complementary observations at all local times, with optimal conjunction of measurements occurring near the equator. The observations are accompanied by a suite of advanced numerical models and analysis techniques. [less ▲]

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