Seasonal variation of neutral thermospheric constituents in the Northern Hemisphere

Mauersberger, K.; Kayser, D. C.; Potter, W. E.; Nier, Alfred O.

doi:10.1029/ja081i001p00007

Cited by 47 publications

(14 citation statements)

References 19 publications

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“…This agrees with laboratory experiments which have shown that atomic oxygen adsorbs on many surfaces [7,8,17]. The realization that atomic oxygen reacts chemically within spaceborne instruments has led to improvements in measurements of upper atmospheric composition [20]. FIGURE 2.…”

Section: Measurements In Spacesupporting

confidence: 77%

Gas-Surface Interactions in Low-Earth Orbit

Moe

2011

AIP Conference Proceedings

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Abstract. When the space age began, some aerodynamicists expected that the surfaces of spacecraft would be cleaned by desorption in the high vacuum of space; while others, familiar with experiments on engineering surfaces, believed that satellite surfaces would be contaminated. During subsequent decades, satellite evidence has accumulated, showing that surfaces in low-Earth orbit are contaminated by adsorbed atomic oxygen and its reaction products. These contaminants cause accommodation coefficients to be high, and the angular distribution of reemitted molecules to be nearly diffuse. These surface conditions must be considered in calculating satellite drag coefficients in free-molecular flow. We describe the experimental and theoretical developments which have led to these conclusions.

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Section: Measurements In Spacesupporting

confidence: 77%

Gas-Surface Interactions in Low-Earth Orbit

Moe

2011

AIP Conference Proceedings

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“…Other complicating factors include the thermalization and/or recombination of incoming atoms in the ionizer stage, 35 and reactions of AO with contaminants both inside and outside the instrument. 36,37 It is reported in the literature that problems associated with recombination of AO within the device can be limited by the use of titanium for all internal surfaces of the spectrometer. 38 It has also been found that changing the design of the spectrometer ionization source from its traditionally closed, to an open or semiopen construction, can reduce problems associated with thermalization and reaction of atoms.…”

Section: A Mass Spectrometersmentioning

confidence: 99%

Satellite and rocket-borne atomic oxygen sensor techniques

Osborne¹,

Harris

Roberts

et al. 2001

Review of Scientific Instruments

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Neutral atomic oxygen (AO)—the dominant atmospheric species at typical low Earth orbit altitudes—is responsible for the erosion, or other degradation, of many satellite materials. Therefore, AO has become an important consideration for spacecraft designers and manufacturers. The study of AO is also of interest to atmospheric physicists because it is involved in many of the chemical reactions occurring naturally in the mesosphere and lower thermosphere. Both these groups rely on atmospheric models for computer-based simulation and prediction of atomic oxygen concentrations. Such models require, or are enhanced by, empirical input data—that is, actual measurements of AO number densities. A review is presented of the different measurement techniques that, to date, have been used on satellites and sounding rockets to perform AO studies. Rather than reporting results from every sensor application, this article takes a more general view of the experimental methods, using example devices to highlight their advantages and disadvantages. New or promising equipment, or techniques that could be exploited for performing such measurements, are also described. We attempt some semiquantitative comparison of the techniques, although the most appropriate experimental method for any given flight opportunity depends heavily on the mission conditions and science goals. Our emphasis is on missions where the available mass and power are limited. In these situations the most suitable established device is probably that of the thin film actinometer. If more risk can be assumed then a more promising, but as yet unqualified, method is that of the fiber-optic reflectance sensor. However, since both these devices are nonreusable, it is shown that semiconducting sensors may be better for long duration, mass- and power-limited applications.

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“…The TIMED/GUVI observations have provided a significant database of O/N 2 behavior through the recent solar cycle [ Zhang and Paxton , 2011] to assist in the interpretation of mass density changes to geomagnetic activity [e.g., Lei et al , 2010] due to dynamic changes in the molecular nitrogen to oxygen transition altitude. However, oxygen to helium behavior in the upper thermosphere at solar minimum has not been observed since the 1970s by the Atmosphere Explorer satellites [ Mauersberger et al , 1976], is far less understood, and is at a much lower altitude than normal during this extreme solar minimum in 2008. Furthermore, the effect of the structure in the oxygen to helium transition on mass density will be more acute than the nitrogen to oxygen transition because of the greater relative change in mean molecular weight, which, as will be shown, can be more dominant than the effects due to temperature during this period.…”

Section: Introductionmentioning

confidence: 99%

The impact of helium on thermosphere mass density response to geomagnetic activity during the recent solar minimum

Thayer¹,

Liu²,

Lei³

et al. 2012

J. Geophys. Res.

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High‐resolution mass density observations inferred from accelerometer measurements on the CHAMP and GRACE satellites are employed to investigate the thermosphere mass density response with latitude and altitude to geomagnetic activity during the recent solar minimum. Coplanar orbital periods in February 2007 and December 2008 revealed the altitude and latitude response in thermosphere mass density for their respective winter hemispheres was influenced by the relative amount of helium and oxygen present. The CHAMP‐to‐GRACE (C/G) mass density ratio depends on two terms; the first proportional to the ratio of the mean molecular weight to temperature and the second proportional to the vertical gradient of the logarithmic mean molecular weight. For the relative levels of helium and oxygen in February 2007, the winter hemisphere C/G mass density response to geomagnetic activity, although similar to the summer hemisphere, was caused predominantly by changes in the vertical gradient of the logarithmic mean molecular weight. In December 2008, the significant presence of helium caused the mean molecular weight changes to exceed temperature changes in the winter hemisphere leading to an increase in the C/G ratio with increasing geomagnetic activity, in opposition to the decrease observed in the summer hemisphere that was caused primarily by temperature changes. The observed behavior is indicative of composition effects influencing the mass density response and the dynamic action of the oxygen to helium transition region in both latitude and altitude will lead to complex behaviors in the mass density at GRACE altitudes throughout the extended solar minimum from 2007 to 2010.

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Seasonal variation of neutral thermospheric constituents in the Northern Hemisphere

Cited by 47 publications

References 19 publications

Gas-Surface Interactions in Low-Earth Orbit

Gas-Surface Interactions in Low-Earth Orbit

Satellite and rocket-borne atomic oxygen sensor techniques

The impact of helium on thermosphere mass density response to geomagnetic activity during the recent solar minimum

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