The Mesosphere and Metals: Chemistry and Changes

Plane, J. M. C.; Feng, Wuhu; Dawkins, E. C. M.

doi:10.1021/cr500501m

Cited by 247 publications

(468 citation statements)

References 324 publications

(836 reference statements)

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“…Their compositions (iron oxides and silicates) are identical, so both SN and meteoritic materials would experience similar chemical reactions in the atmosphere. Because of these similarities, we use the extensive work already accomplished on meteoric smoke particles (e.g., Plane et al 2015, and references therein).…”

Section: Wind Deflectionmentioning

confidence: 99%

RADIOACTIVE IRON RAIN: TRANSPORTING⁶⁰Fe IN SUPERNOVA DUST TO THE OCEAN FLOOR

Fry

Fields

Ellis

2016

ApJ

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Several searches have found evidence of Fe 60 deposition, presumably from a near-Earth supernova (SN), with concentrations that vary in different locations on Earth. This paper examines various influences on the path of interstellar dust carrying Fe 60 from an SN through the heliosphere, with the aim of estimating the final global distribution on the ocean floor. We study the influences of magnetic fields, angle of arrival, wind, and ocean cycling of SN material on the concentrations at different locations. We find that the passage of SN material through the mesosphere/lower thermosphere has the greatest influence on the final global distribution, with ocean cycling causing lesser alteration as the SN material sinks to the ocean floor. SN distance estimates in previous works that assumed a uniform distribution are a good approximation. Including the effects on surface distributions, we estimate a distance of -+ 46 610 pc for an -SN progenitor. This is consistent with an SN occurring within the Tuc-Hor stellar group ∼2.8 Myr ago, with SN material arriving on Earth ∼2.2 Myr ago. We note that the SN dust retains directional information to within 1• through its arrival in the inner solar system, so that SN debris deposition on inert bodies such as the Moon will be anisotropic, and thus could in principle be used to infer directional information. In particular, we predict that existing lunar samples should show measurable Fe 60 differences.

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Section: Wind Deflectionmentioning

confidence: 99%

RADIOACTIVE IRON RAIN: TRANSPORTING⁶⁰Fe IN SUPERNOVA DUST TO THE OCEAN FLOOR

Fry

Fields

Ellis

2016

ApJ

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“…The metal layers in the mesosphere and lower thermosphere (MLT) are formed by ablation from meteoroids entering the Earth's atmosphere (see, e.g., Plane (2003) and Plane et al (2015) for reviews). The main source of these meteoroids is cometary dust from the Jupiter-family comets (see, e.g., Nesvorný et al, 2010), which produce a dominating contin- Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…At the upper edge of the metal layers (above 90 km) the metal atoms are ionized. Throughout the whole layer, especially at the bottom, the metals react to form molecular species such as carbonates, hydroxides and oxides (see, e.g., Plane et al, 2015). These molecules further are involved in chemical processes and produce condensation nuclei for the formation of particles eventually resulting in meteoric smoke particles (see, e.g., Hunten et al, 1980;Kalashnikova et al, 2000;Saunders and Plane, 2006;Havnes and Naesheim, 2007;Hervig et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Comparison of global datasets of sodium densities in the mesosphere and lower thermosphere from GOMOS, SCIAMACHY and OSIRIS measurements and WACCM model simulations from 2008 to 2012

Langowski¹,

Savigny²,

Burrows³

et al. 2017

Atmos. Meas. Tech.

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Abstract. During the last decade, several limb sounding satellites have measured the global sodium (Na) number densities in the mesosphere and lower thermosphere (MLT). Datasets are now available from Global Ozone Monitoring by Occultation of Stars (GOMOS), the SCanning Imaging Absorption spectroMeter for Atmospheric CHartography (SCIAMACHY) (both on Envisat) and the Optical Spectrograph and InfraRed Imager System (OSIRIS) (on Odin). Furthermore, global model simulations of the Na layer in the MLT simulated by the Whole Atmosphere Community Climate Model, including the Na species (WACCM-Na), are available. In this paper, we compare these global datasets.The observed and simulated monthly averages of Na vertical column densities agree reasonably well with each other. They show a clear seasonal cycle with a summer minimum most pronounced at the poles. They also show signs of a semi-annual oscillation in the equatorial region. The vertical column densities vary from 0.5 × 10 9 to 7 × 10 9 cm −2 near the poles and from 3 × 10 9 to 4 × 10 9 cm −2 at the Equator. The phase of the seasonal cycle and semi-annual oscillation shows small differences between the Na amounts retrieved from different instruments. The full width at half maximum of the profiles is 10 to 16 km for most latitudes, but significantly smaller in the polar summer. The centroid altitudes of the measured sodium profiles range from 89 to 95 km, whereas the model shows on average 2 to 4 km lower centroid altitudes. This may be explained by the mesopause being 3 km lower in the WACCM simulations than in measurements. Despite this global 2-4 km shift, the model captures well the latitudinal and temporal variations. The variation of the WACCM dataset during the year at different latitudes is similar to the one of the measurements. Furthermore, the differences between the measured profiles with different instruments and therefore different local times (LTs) are also present in the model-simulated profiles. This capturing of latitudinal and temporal variations is also found for the vertical column densities and profile widths.

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“…The ablated metals are transported and react with the ambient neutral atmosphere. As a result metal layers are formed that have peak densities at around 85-95 km altitude (see e.g., Plane, 2003;Plane et al, 2015 for a review). Although the metal concentrations of several thousand atoms per cubic centimeter are low, these metals are strong emitters of radiation because they have large resonance fluorescence cross sections.…”

mentioning

confidence: 99%

Retrieval of sodium number density profiles in the mesosphere and lower thermosphere from SCIAMACHY limb emission measurements

Langowski¹,

Savigny²,

Burrows³

et al. 2016

Atmos. Meas. Tech.

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Abstract. An algorithm has been developed for the retrieval of sodium atom (Na) number density on a latitude and altitude grid from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) limb measurements of the Na resonance fluorescence. The results are obtained between 50 and 150 km altitude and the resulting global seasonal variations of Na are analyzed. The retrieval approach is adapted from that used for the retrieval of magnesium atom (Mg) and magnesium ion (Mg + ) number density profiles recently reported by Langowski et al. (2014). Monthly mean values of Na are presented as a function of altitude and latitude. This data set was retrieved from the 4 years of spectroscopic limb data of the SCIAMACHY mesosphere and lower thermosphere (MLT) measurement mode (mid-2008 to early 2012).The Na layer has a nearly constant peak altitude of 90-93 km for all latitudes and seasons, and has a full width at half maximum of 5-15 km. Small but significant seasonal variations in Na are identified for latitudes less than 40 • , where the maximum Na number densities are 3000-4000 atoms cm −3 . At middle to high latitudes a clear seasonal variation with a winter maximum of up to 6000 atoms cm −3 is observed. The high latitudes, which are only measured in the summer hemisphere, have lower number densities, with peak densities being approximately 1000 Na atoms cm −3 . The full width at half maximum of the peak varies strongly at high latitudes and is 5 km near the polar summer mesopause, while it exceeds 10 km at lower latitudes. In summer the Na atom concentration at high latitudes and at altitudes below 88 km is significantly smaller than that at middle latitudes. The results are compared with other observations and models and there is overall a good agreement with these.

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The Mesosphere and Metals: Chemistry and Changes

Cited by 247 publications

References 324 publications

RADIOACTIVE IRON RAIN: TRANSPORTING⁶⁰Fe IN SUPERNOVA DUST TO THE OCEAN FLOOR

RADIOACTIVE IRON RAIN: TRANSPORTING⁶⁰Fe IN SUPERNOVA DUST TO THE OCEAN FLOOR

Comparison of global datasets of sodium densities in the mesosphere and lower thermosphere from GOMOS, SCIAMACHY and OSIRIS measurements and WACCM model simulations from 2008 to 2012

Retrieval of sodium number density profiles in the mesosphere and lower thermosphere from SCIAMACHY limb emission measurements

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The Mesosphere and Metals: Chemistry and Changes

Cited by 247 publications

References 324 publications

RADIOACTIVE IRON RAIN: TRANSPORTING60Fe IN SUPERNOVA DUST TO THE OCEAN FLOOR

RADIOACTIVE IRON RAIN: TRANSPORTING60Fe IN SUPERNOVA DUST TO THE OCEAN FLOOR

Comparison of global datasets of sodium densities in the mesosphere and lower thermosphere from GOMOS, SCIAMACHY and OSIRIS measurements and WACCM model simulations from 2008 to 2012

Retrieval of sodium number density profiles in the mesosphere and lower thermosphere from SCIAMACHY limb emission measurements

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RADIOACTIVE IRON RAIN: TRANSPORTING⁶⁰Fe IN SUPERNOVA DUST TO THE OCEAN FLOOR

RADIOACTIVE IRON RAIN: TRANSPORTING⁶⁰Fe IN SUPERNOVA DUST TO THE OCEAN FLOOR