Ionic and neutral concentrations of Mg and Fe near 92 km

Swider, W.

doi:10.1016/0032-0633(84)90166-1

Cited by 40 publications

(23 citation statements)

References 32 publications

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“…These increases appear to be principally due to the presence of metal ions (Fe + , Mg + ), probably of meteor origin, left over from daytime ionization. The metal ion recombination rate is very slow; so the metal ions and their electrons can survive the night at levels of ∼10 3 el/cm 3 near 90 km [e.g., Aikin and Goldberg , 1973; Swider , 1984; Kopp , 1997].…”

Section: Discussionmentioning

confidence: 99%

Nighttime ionospheric D region parameters from VLF phase and amplitude

2007

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[1] Nighttime ionospheric D region heights and electron densities are determined from an extensive set of VLF radio phase and amplitude observations. The D region parameters are characterized by the traditional H 0 (height in kilometers) and b (sharpness in km À1 ) as used by Wait and by the U. S. Navy in their Earth-ionosphere waveguide programs. The VLF measurements were made with several frequencies in the range 10 kHz to 41 kHz on long, mainly all-sea paths, including Omega La Reunion and Omega Argentina to Dunedin, New Zealand, NAU (Puerto Rico) and NAA (Maine, USA) to Cambridge, UK, and NPM (Hawaii) to San Francisco. Because daytime VLF propagation on such paths is readily measured and predicted, the differences between night and day amplitudes and phases were measured and compared with calculations for a range of nighttime ionospheric parameters. This avoided the problem of uncertainties in the transmitter powers. In this way the height, H 0 , and the sharpness, b, when averaged over periods of several days, at least for the midlatitude D region near solar minimum, were found to be 85.1 ± 0.4 km and 0.63 ± 0.04 km À1 , respectively.

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Section: Discussionmentioning

confidence: 99%

Nighttime ionospheric D region parameters from VLF phase and amplitude

2007

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“…profiles were obtained during a total observation period of 28 hrs on these 4 nights. Tepley et al[1981] and used the same technique to measure Fe abundances below 90 km at Arecibo Observatory which were less than !09 cm -2 Swider [1984]. On this night the centroid height of the layer was near 89 km where the densities varied between Oclober 26, 1989 105 ........ , .... , ..... , .... Fe density profile collected at Urbana on October 26, 1989 at 2350 LST.…”

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confidence: 89%

Lidar observations of mesospheric Fe and sporadic Fe layers at Urbana, Illinois

Bills

Gardner

1990

Geophysical Research Letters

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Lidar measurements of mesospheric Fe were conducted at Urbana, IL (40°N, 88°W) during 4 nights in late October 1989. The average Fe abundances, layer centroid heights and rms widths varied between 1.0 – 2.0×1010 cm−2, 89.0 – 90.5 km and 3.2 – 4.1 km, respectively. The peak densities of the layer near 90 km varied between 15 – 25×103 cm−3. Considerable gravity wave and tidal activity was observed in the Fe profiles. On 3 nights the formation and dissipation of 3 large sporadic Fe (Fes) layers was observed. These are the first observations of this phenomenon. The 2 largest Fes layers formed at 102.4 km and 91.4 km over a period of about 20 min and their widths were approximately 2.3 km FWHM. The peak densities of the Fes layers were as high as 31×103 cm−3 and the abundances were as high as 5.8×109 cm−2. The observations are compared with previous measurements of mesospheric Fe and with recent observations of sporadic Na (Nas) layers.

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“…6). Swider (1984) Mg layer is Mg(OH) 2 . This is reduced back to Mg via MgOH by reaction with H atoms (R12a).…”

Section: Waccm-mg Modelmentioning

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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Ionic and neutral concentrations of Mg and Fe near 92 km

Cited by 40 publications

References 32 publications

Nighttime ionospheric D region parameters from VLF phase and amplitude

Nighttime ionospheric D region parameters from VLF phase and amplitude

Lidar observations of mesospheric Fe and sporadic Fe layers at Urbana, Illinois

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

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