Simultaneous observations of neutral and ionic magnesium in the thermosphere

Gardner, James A.; Viereck, R. A.; Murad, Edmond; Knecht, David J.; Pike, C. P.; Broadfoot, A. L.; Anderson, E.

doi:10.1029/95gl01769

Cited by 36 publications

(35 citation statements)

References 23 publications

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“…Other analyses of data from OGO-4 and OGO-6 (Taylor, 1973), ESRO TD-1A (Gerard, 1976;Gerard and Mon®ls, 1978), and AE-C and AE-E (Grebowsky and Brinton, 1978;Grebowsky and Reese, 1989) revealed similar ion densities, consistent with the idea of upward vertical transport near the magnetic equator. Recent observations by the GLO instrument on the Space Shuttle have provided the ®rst simultaneous observations of Mg and Mg + in the thermosphere (Gardner et al, 1995). The salient features of the Mg + distributions near the magnetic equator appear to be driven by vertical E´B drifts (McNeil et al, 1996).…”

Section: Brief History Of Observational Workmentioning

confidence: 99%

Global transport and localized layering of metallic ions in the upper atmospherer

Carter

Forbes

1999

Ann. Geophys.

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Abstract. A numerical model has been developed which is capable of simulating all phases of the life cycle of metallic ions, and results are described and interpreted herein for the typical case of Fe + ions. This cycle begins with the initial deposition of metallics through meteor ablation and sputtering, followed by conversion of neutral Fe atoms to ions through photoionization and charge exchange with ambient ions. Global transport arising from daytime electric ®elds and poleward/ downward diusion along geomagnetic ®eld lines, localized transport and layer formation through descending convergent nulls in the thermospheric wind ®eld, and ®nally annihilation by chemical neutralization and compound formation are treated. The model thus sheds new light on the interdependencies of the physical and chemical processes aecting atmospheric metallics. Model output analysis con®rms the dominant role of both global and local transport to the ion's life cycle, showing that upward forcing from the equatorial electric ®eld is critical to global movement, and that diurnal and semidiurnal tidal winds are responsible for the formation of dense ion layers in the 90±250 km height region. It is demonstrated that the assumed combination of sources, chemical sinks, and transport mechanisms actually produces F-region densities and E-region layer densities similar to those observed. The model also shows that zonal and meridional winds and electric ®elds each play distinct roles in local transport, whereas the ion distribution is relatively insensitive to reasonable variations in meteoric deposition and chemical reaction rates.

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Section: Brief History Of Observational Workmentioning

confidence: 99%

Global transport and localized layering of metallic ions in the upper atmospherer

Carter

Forbes

1999

Ann. Geophys.

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“…No Mg signal above the instrumental noise was observed in these spectra. The region above the peak altitude from 150 km up to the F-layer and above was investigated by Gérard and Monfils (1978), Fesen and Hays (1982a), Mende et al (1985), Gardner et al (1995) and Gardner et al (1999) and typically shows less than 100 cm −3 Mg + ions at 150 km altitude. This is in good agreement with the profiles described in Sect.…”

Section: Comparison To Other Measurementsmentioning

confidence: 99%

Global investigation of the Mg atom and ion layers using SCIAMACHY/Envisat observations between 70 and 150 km altitude and WACCM-Mg model results

et al. 2015

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Abstract. Mg and Mg + concentration fields in the upper mesosphere/lower thermosphere (UMLT) region are retrieved from SCIAMACHY/Envisat limb measurements of Mg and Mg + dayglow emissions using a 2-D tomographic retrieval approach. The time series of monthly mean Mg and Mg + number density and vertical column density in different latitudinal regions are presented. Data from the limb mesosphere-thermosphere mode of SCIAMACHY/Envisat are used, which cover the 50 to 150 km altitude region with a vertical sampling of ≈ 3.3 km and latitudes up to 82• . The high latitudes are not observed in the winter months, because there is no dayglow emission during polar night. The measurements were performed every 14 days from mid-2008 until April 2012. Mg profiles show a peak at around 90 km altitude with a density between 750 cm −3 and 1500 cm −3 . Mg does not show strong seasonal variation at latitudes below 40 • . For higher latitudes the density is lower and only in the Northern Hemisphere a seasonal cycle with a summer minimum is observed. The Mg + peak occurs 5-15 km above the neutral Mg peak altitude. These ions have a significant seasonal cycle with a summer maximum in both hemispheres at mid and high latitudes. The strongest seasonal variations of Mg + are observed at latitudes between 20 and 40• and the density at the peak altitude ranges from 500 cm −3 to 4000 cm −3 . The peak altitude of the ions shows a latitudinal dependence with a maximum at mid latitudes that is up to 10 km higher than the peak altitude at the equator.The SCIAMACHY measurements are compared to other measurements and WACCM model results. The WACCM results show a significant seasonal variability for Mg with a summer minimum, which is more clearly pronounced than for SCIAMACHY, and globally a higher peak density than the SCIAMACHY results. Although the peak density of both is not in agreement, the vertical column density agrees well, because SCIAMACHY and WACCM profiles have different widths. The agreement between SCIAMACHY and WACCM results is much better for Mg + with both showing the same seasonality and similar peak density. However, there are also minor differences, e.g. WACCM showing a nearly constant altitude of the Mg + layer's peak density for all latitudes and seasons.

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“…Indeed, Mg is among the most abundant cosmic metals and it is a major constituent of chondritic meteorites. 4,5 In Earth's atmosphere, the Mg + cation is 4 to 12 times more abundant than neutral Mg. 6,7 Magnesium in the upper portions of Earth's atmosphere is provided by meteoritic ablation, where it is present as atomic and ionized Mg 2+ , especially in the ionosphere. Mg 2+ travelling through the lower atmosphere layers should react, at least with O, and contribute to the increase in the Mg + /Mg ratio.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the MgO²⁺dication in the gas phase: electronic states, spectroscopy and atmospheric implications

Linguerri

Hochlaf

Bacchus‐Montabonel

et al. 2013

Phys. Chem. Chem. Phys.

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Simultaneous observations of neutral and ionic magnesium in the thermosphere

Cited by 36 publications

References 23 publications

Global transport and localized layering of metallic ions in the upper atmospherer

Global transport and localized layering of metallic ions in the upper atmospherer

Global investigation of the Mg atom and ion layers using SCIAMACHY/Envisat observations between 70 and 150 km altitude and WACCM-Mg model results

Characterization of the MgO²⁺dication in the gas phase: electronic states, spectroscopy and atmospheric implications

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Simultaneous observations of neutral and ionic magnesium in the thermosphere

Cited by 36 publications

References 23 publications

Global transport and localized layering of metallic ions in the upper atmospherer

Global transport and localized layering of metallic ions in the upper atmospherer

Global investigation of the Mg atom and ion layers using SCIAMACHY/Envisat observations between 70 and 150 km altitude and WACCM-Mg model results

Characterization of the MgO2+dication in the gas phase: electronic states, spectroscopy and atmospheric implications

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Characterization of the MgO²⁺dication in the gas phase: electronic states, spectroscopy and atmospheric implications