Novel Experimental Simulations of the Atmospheric Injection of Meteoric Metals

Martı́n, Juan Carlos Gómez; Bones, David L.; Carrillo‐Sánchez, J. D.; James, Alexander D.; Trigo-Rodríguez, J. M.; Fegley, B.; Plane, J. M. C.

doi:10.3847/1538-4357/aa5c8f

Cited by 38 publications

(47 citation statements)

References 74 publications

(116 reference statements)

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“…Due to the lack of experimental data, the apparent evaporation coefficient for each metal is assumed to be the same for all the compounds of the bulk, such that g g = i (Vondrak et al 2008). The range of temperature where the solid and the liquid are in equilibrium is treated by applying a phase transition factor f (T) (Gómez Martín et al 2017), which is represented by a sigmoid temperature dependence weighting that varies between 0 and 1:…”

Section: Cabmod Improvementsmentioning

confidence: 99%

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. III. The Role of Sodium and the Head Echo Size on the Probability of Detection

Janches

Swarnalingam

Carrillo‐Sánchez

et al. 2017

ApJ

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We present a path forward on a long-standing issue concerning the flux of small and slow meteoroids, which are believed to be the dominant portion of the incoming meteoric mass flux into the Earth's atmosphere. Such a flux, which is predicted by dynamical dust models of the Zodiacal Cloud, is not evident in ground-based radar observations. For decades this was attributed to the fact that the radars used for meteor observations lack the sensitivity to detect this population, due to the small amount of ionization produced by slow-velocity meteors. Such a hypothesis has been challenged by the introduction of meteor head echo (HE) observations with High Power and Large Aperture radars, in particular the Arecibo 430 MHz radar. Janches et al. developed a probabilistic approach to estimate the detectability of meteors by these radars and initially showed that, with the current knowledge of ablation and ionization, such particles should dominate the detected rates by one to two orders of magnitude compared to the actual observations. In this paper, we include results in our model from recently published laboratory measurements, which showed that (1) the ablation of Na is less intense covering a wider altitude range; and (2) the ionization probability, b ip , for Na atoms in the air is up to two orders of magnitude smaller for low speeds than originally believed. By applying these results and using a somewhat smaller size of the HE radar target we offer a solution that reconciles these observations with model predictions.

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Section: Cabmod Improvementsmentioning

confidence: 99%

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. III. The Role of Sodium and the Head Echo Size on the Probability of Detection

Janches

Swarnalingam

Carrillo‐Sánchez

et al. 2017

ApJ

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“…The first was to incorporate the comprehensive new data-base of neutral and 10 ion-molecule reactions of Ca pertinent to the MLT (Table 1), together with a new meteoric input function for Ca (CarrilloSánchez et al, 2016) that had been validated experimentally (Gómez-Martín et al, 2017), into a global chemistry-climate model. The second objective was then to explain the more than 100-fold depletion of atomic Ca relative to Na compared with their relative CI abundance; and the third was to explain why the Ca + ion abundance is depleted by only a factor of ~3 with respect to Na + between 90 and 100 km.…”

Section: Discussionmentioning

confidence: 99%

“…In another development, we have recently constructed a Meteoric Ablation Simulator (MASI) to study experimentally the ablation of different metals from meteoritic fragments, under heating conditions that simulate atmospheric entry (Bones et al, 2016b). Work with the simulator has confirmed that Ca does indeed ablate much less efficiently than Na from meteoritic particles, and allowed the Chemical Ablation Model (CABMOD) to be refined and validated (Gómez-Martín et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

A new model of meteoric calcium in the mesosphere and lower thermosphere

Plane¹,

Feng²,

Martı́n³

et al. 2018

Preprint

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Abstract. Meteoric ablation produces layers of metal atoms in the mesosphere and lower thermosphere (MLT). It has been known for more than 30 years that the Ca atom layer is depleted by over 2 orders of magnitude compared with Na, despite these elements having essentially the same elemental abundance in chondritic meteorites. In contrast, the Ca + ion abundance 15 is depleted by less than a factor of 10. To explain these observations, a large data-base of neutral and ion-molecule reaction kinetics of Ca species, measured over the past decade, was incorporated into the Whole Atmosphere Community Climate Model (WACCM). A new meteoric input function for Ca and Na, derived using a chemical ablation model that has been tested experimentally with a Meteoric Ablation Simulator, shows that Ca experiences significant differential ablation, by almost 1 order of magnitude, with respect to Na. WACCM-Ca simulates the seasonal Ca layer satisfactorily when compared with lidar 20 observations, but tends to overestimate Ca + measurements made by rocket mass spectrometry and lidar. A key finding is that CaOH and CaCO3 are very stable reservoir species because they are involved in essentially closed reaction cycles with O2 andO. This has been demonstrated experimentally for CaOH, and in this study for CaCO3 using electronic structure and statistical rate theory. Most of the neutral Ca is therefore locked in these reservoirs, enabling rapid loss through polymerization into meteoric smoke particles and explaining the extreme depletion of Ca. 25

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“…Recently, a Meteoric Ablation Simulator (MASI) has been developed to test the predictions of ablation models like CABMOD (Bones et al 2016;Gómez Martín et al 2017). The MASI heats a meteoritic particle (r = 20-200 µm) over a temperature ramp (up to 2800 K) that is programmed to match atmospheric entry for a specified velocity, and measures the absolute rates of evaporation of pairs of metal atoms (e.g.…”

Section: Meteoric Ablationmentioning

confidence: 99%

“…the evaporation of relatively volatile elements such as Na and K before the main elements Fe, Mg and Si, and finally the refractory elements Ca, Ti and Al. However, the ablation profiles of individual species tend to be broader than predicted by a model such as CABMOD because meteorites do not consist of single mineral phases (Gómez Martín et al 2017). …”

Section: Meteoric Ablationmentioning

confidence: 99%

Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces

et al. 2017

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Recent advances in interplanetary dust modelling provide much improved estimates of the fluxes of cosmic dust particles into planetary (and lunar) atmospheres throughout the solar system. Combining the dust particle size and velocity distributions with new chemical ablation models enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; and the effects of the surface deposition of micrometeorites and cosmic spherules. There is discussion of impacts on all the planets, as well as on Pluto, Triton and Titan.

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Novel Experimental Simulations of the Atmospheric Injection of Meteoric Metals

Cited by 38 publications

References 74 publications

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. III. The Role of Sodium and the Head Echo Size on the Probability of Detection

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. III. The Role of Sodium and the Head Echo Size on the Probability of Detection

A new model of meteoric calcium in the mesosphere and lower thermosphere

Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces

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