Influence of surface recombination in satellite atomic oxygen measurements inferred from the AEROS‐A mass spectrometer

Lake, L. R.; Krankowsky, D.

doi:10.1029/gl002i012p00545

Cited by 3 publications

(3 citation statements)

References 6 publications

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“…The drag-determined atomic oxygen concentrations are considerably higher than determined from the ONMS experiment [Niemann et aL, 1979c]. This may result from atomic oxygen losses on the walls of the mass spectrometer [yon Zahn, 1970;Lake and Krankowsky, 1975;Hedin et al, 1973]. Thus, the OAD model sensitivity studies indicate that the atomic oxygen concentrations and exospheric temperatures tabulated in Table 2 are probably accurate.…”

Section: Shown Inmentioning

confidence: 99%

Venus upper atmosphere structure

1980

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From analysis of the orbiter atmospheric drag (OAD) data obtained from the orbital decay of the Pioneer Venus orbiter from December 9, 1978, to August 7, 1979, atmospheric densities have been determined and tabulated near 16°N latitude between 140 and 190 km for all times of day. Maximum daytime densities on Venus are approximately 8 × 10−13 g cm−3 at an altitude of 150 km (dropping by a factor of 24 at night) and 7 × 10−14 g cm−3 at 170 km (dropping by a factor of 82 at night). Comparative atmospheric densities on earth at 150 km are a factor of 3.5 higher during the day with only a 1% diurnal variation. An atmospheric composition, temperature, and density model based on OAD vertical structure measurements is presented. The inferred exospheric temperatures and atomic oxygen concentrations are surprisingly insensitive to model assumptions. This model indicates that atomic oxygen is the major species in the Venus atmosphere above 145 km at night and above 160 km during the day with mixing ratios near 140 km in excess of 0.1. Atomic oxygen concentrations determined from drag measurements near 170 km range from 1 × 109 cm−3 during the day to 3 × 107 cm−3 at night. Exospheric temperatures inferred from OAD measurements are found to vary from 100°K at night to approximately 300°K during the day. The very low exospheric temperatures discovered at night, lower than temperatures near 100 km, are inconsistent with the concept of a planetary thermosphere, in which temperature increases with altitude. We have adopted the term ‘cryosphere’ to define this region of cooling where temperature decreases with altitude. The phase of the diurnal temperature variation is consistent with theoretical models of an atmosphere with mean motion to the west more rapid than planetary rotation superimposed on solar‐antisolar motion. The very low nighttime temperatures and our observation of an absence of the predicted nighttime atomic oxygen bulge suggest substantial downward eddy transport of heat as well as of atomic oxygen. Finally, the OAD data indicate that the neutral upper atmosphere of Venus is unexpectedly insensitive to both solar extreme ultraviolet variations and variations in the solar wind. Thus, the Venus upper atmosphere may not be controlled by the major heating mechanisms generally assumed for planetary thermospheres.

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Section: Shown Inmentioning

confidence: 99%

Venus upper atmosphere structure

1980

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“…In the case of molecular oxygen, much of what is presently known about these relationships has been deduced from optical measurements of [O0] taken on rockets [Weeks, 1975;Higgins and Heroux, 1977] and satellites, (e.g., May, 1973;Hays and Robie, 1973;Norton and Robie, 1974;Atreya et al, 1976] during a variety of geomagnetic conditions. While mass spectrometer measurements of [O0] have been made by rocket-borne experiments [see Offermann, 1974, for review] in the past, substantive measurements by satellite mass spectrometers have not been available owing to source chemistry considerations [Hedin et al, 1973;Lake and Krankowsky, 1975 I I I I I I I I I I I I I I The daily average Ap during the period covered in Figure 1 has been plotted as a function of time in Figure 2. For reference the daily Fx0., solar flux index has been added; it was generally between 70 and 80 except for periods in mid-November and January.…”

Section: Introduction Observationsmentioning

confidence: 99%

Thermal and wind‐induced variations in thermospheric molecular oxygen as measured on AE‐D

Potter

Kayser²,

Nier

1979

J. Geophys. Res.

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Simultaneous measurements of ambient [O2], [N2], and temperature were made near winter solstice, 1975, by the open source neutral mass spectrometer (OSS) on Atmosphere Explorer‐D. The data, taken at midmorning and all latitudes, are analyzed by using scatter plots and correlation coefficients. At 200 km the [O2] density exhibits a positive correlation with the magnetic indices. Owing to the latitude dependence, this description of the response of [O2] during or following periods of magnetic activity, while it is useful, is only qualitative. The increase in [O2] with increasing ambient temperature is much better defined over a wide range of latitudes. In addition to temperature, global scale wind systems may play a role in controlling the distribution of [O2]. To study this role further, measurements of [N2] are used to help distinguish between temperature and wind effects in [O2]. A survey of the latitudinal variations in [O2]/[N2] with temperature indicates a positive response in high‐latitude regions and a negative response near the equator. This is further substantiated with the calculation of correlation coefficients. Such an effect can be explained by inferring the existence of upward vertical winds at high latitudes, meridional flow toward lower latitudes, and subsidence near the equator. Such wind systems are in agreement with those predicted by models and measured in the high‐latitude regions. It is concluded that [O2], being a minor constituent, is controlled both by temperature variations and by wind induced diffusion.

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“…Philbrick [1974] reported that a low recombination coefficient of about 0.01 was achieved with closed and semiopen ion sources constructed of titanium. A gold-plated open source design of Krankowsky et al [1974] led to a less than complete and also altitude-variable recombination coefficient [Lake and Krankowsky, 1975]. Closed source instruments, where the source chamber is gold or gold plated, appear to effect nearly complete recombination of atomic to molecular oxygen [Hedin et al, 1973 was constructed mostly of stainless steel, Nichrome V, and aluminum.…”

Section: Introductionmentioning

confidence: 99%

A technique for mass spectrometer measurements of atomic and molecular oxygen in the lower thermosphere

Kayser

Potter

1978

J. Geophys. Res.

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A neutral mass spectrometer with a quasi‐open ion source was flown on each of the Atmosphere Explorer (AE) C, D, and E satellites. The three instruments provided an opportunity to study the effects of different source insert materials on the source surface chemistry. It was found that, after a period of conditioning in space, the recombination coefficient of atomic oxygen on gold appears to be substantially lower than it is on Nichrome V. The lower recombination coefficient on gold allows the spectrometer to directly measure a significant fraction of the incident atomic oxygen, making it possible to distinguish between ambient O and O2. Equations are developed to calculate the atomic and molecular oxygen densities. Preliminary measurements of molecular oxygen densities obtained by this technique agree well with measurements taken in the fly‐through mode of operation.

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Influence of surface recombination in satellite atomic oxygen measurements inferred from the AEROS‐A mass spectrometer

Cited by 3 publications

References 6 publications

Venus upper atmosphere structure

Venus upper atmosphere structure

Thermal and wind‐induced variations in thermospheric molecular oxygen as measured on AE‐D

A technique for mass spectrometer measurements of atomic and molecular oxygen in the lower thermosphere

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