Meteoric Metals Research Articles

Spectroscopy of a mesospheric ghost reveals iron emissions

Mesospheric Green emissions from excited Oxygen in Sprite Tops (ghosts) are infrequent and faint greenish transient luminous events that remain for hundreds of milliseconds on top of certain energetic sprites. The main hypothesis to explain this glow persistence is the long lifetime of excited atomic oxygen at 557.73 nm, a well-known emission line in aurora and airglow. However, due to the lack of spectroscopic campaigns to analyse such events to date, the species involved in the process can not yet be identified. Here we report observational results showing the temporal evolution of a ghost spectrum between 500 nm and 600 nm. Besides weak -but certain- traces of excited atomic oxygen, our results show four main contributors related to the slow decay of the glow: atomic iron and nickel, molecular nitrogen and ionic molecular oxygen. Additionally, we are able to identify traces of atomic sodium, and ionic silicon, these observations being consistent with previous direct measurements of density profiles of meteoric metals in the mesosphere and lower thermosphere. This finding calls for an upgrade of current air plasma kinetic understanding under the influence of transient luminous events.

Opinion: Recent developments and future directions in studying the mesosphere and lower thermosphere

Abstract. This article begins with a review of important advances in the chemistry and related physics of the mesosphere and lower thermosphere (MLT) region of the atmosphere that have occurred over the past 2 decades, since the founding of Atmospheric Chemistry and Physics. The emphasis here is on chemistry, but we also discuss recent findings on atmospheric dynamics and forcings to the extent that these are important for understanding MLT composition and chemistry. Topics that are covered include observations, with satellite, rocket and ground-based techniques; the variability and connectedness of the MLT on various length scales and timescales; airglow emissions; the cosmic dust input and meteoric metal layers; and noctilucent/polar mesospheric ice clouds. The paper then concludes with a discussion of important unanswered questions and likely future directions for the field over the next decade.

Phosphorus Chemistry in the Earth's Upper Atmosphere

AbstractThe ablation of phosphorus from interplanetary dust particles entering the Earth's atmosphere is a potentially significant source of this key bioelement. In this study, the atmospheric chemistry of phosphorus is explored by developing a reaction network of possible routes from PO, the major ablation product in the upper mesosphere/lower thermosphere region, to the stable reservoirs H3PO3 and H3PO4 that become incorporated into meteoric smoke particles (MSPs) as metal phosphites and phosphates, respectively. The network is constructed with reactions whose kinetics have been measured experimentally, together with reactions where theoretical rate coefficients are estimated using a combination of electronic structure theory calculations and a Rice‐Ramsperger‐Kassel‐Markus master equation treatment. The network is then incorporated into a global chemistry‐climate model, together with a phosphorus meteoric input function. The estimated global mean P deposition flux, in the form of submicron‐sized MSPs, is 1 × 10−8 g m−2 yr−1, with a maximum of ∼5 × 10−8 g m−2 yr−1 over the northern Rockies, Himalayas, and southern Andes. The estimated fraction of ablated phosphorus forming bioavailable metal phosphites is 11%, which results from the very large concentrations of O and H compared to OH in the upper mesosphere. A layer of OPO is predicted to occur at 90 km with a peak of concentration of ∼50 cm−3; this is the counterpart of the well‐known layers of meteoric metals such as Na and Fe, and may be observable spectroscopically.

The 27‐Day Solar Rotational Cycle Response in the Mesospheric Metal Layers at Low Latitudes

AbstractTo investigate the response of the meteoric metal layers in the mesosphere and lower thermosphere regions to the 27‐day solar rotational cycle, a long‐term simulation of the Whole Atmosphere Community Climate Model with the chemistry of three metals (Na, K, and Fe) was analyzed. The correlation between variability in the metal layers and solar 27‐day forcing during different phases of the solar 11‐year cycle reveals that the response in the metal layers is much stronger during solar maximum. The altitude‐dependent correlation and sensitivity of the metal layers to the solar spectral irradiance demonstrates that there is a significant increase in sensitivity to solar rotational cycle with increasing altitude. Above 100 km, the sensitivity of the metals to changes of 10% in the solar spectral irradiance at Lyman‐alpha is estimated to be −5%. A similar response is seen in Na layer measurements made by the Optical Spectrograph and InfraRed Imaging System instrument on the Odin satellite.

The fate of meteoric metals in ice particles: Effects of sublimation and energetic particle bombardment

The uptake and potential reactivity of metal atoms on water ice can be an important process in planetary atmospheres and on icy bodies in the interplanetary and interstellar medium. For instance, metal atom uptake affects the gas-phase chemistry of the Earth's mesosphere, and has been proposed to influence the agglomeration of matter into planets in protoplanetary disks. In this study the fate of Mg and K atoms incorporated into water-ice films, prepared under ultra-high vacuum conditions at temperatures of 110–140 K, was investigated. Temperature-programmed desorption experiments reveal that Mg- and K-containing species do not co-desorb when the ice sublimates, demonstrating that uptake on ice particles causes irreversible removal of the metals from the gas phase. This implies that uptake on ice particles in terrestrial polar mesospheric clouds accelerates the formation of large meteoric smoke particles (≥1 nm radius above 80 km) following sublimation of the ice. Energetic sputtering of metal-dosed ice layers by 500 eV Ar+ and Kr+ ions shows that whereas K reacts on (or within) the ice surface to form KOH, adsorbed Mg atoms are chemically inert. These experimental results are consistent with electronic structure calculations of the metals bound to an ice surface, where theoretical adsorption energies on ice are calculated to be −68 kJ mol−1 for K, −91 kJ mol−1 for Mg, and −306 kJ mol−1 for Fe. K can also insert into a surface H2O to produce KOH and a dangling H atom, in a reaction that is slightly exothermic.

Formation mechanisms of neutral Fe layers in the thermosphere at Antarctica studied with a thermosphere‐ionosphere Fe/Fe+ (TIFe) model

AbstractWith a thermosphere‐ionosphere Fe/Fe+ (TIFe) model developed from first principles at the University of Colorado, we present the first quantitative investigation of formation mechanisms of thermospheric Fe layers observed by lidar in Antarctica. These recently discovered neutral metal layers in the thermosphere between 100 and 200 km provide unique tracers for studies of fundamental processes in the space‐atmosphere interaction region. The TIFe model formulates and expands the TIFe theory originally proposed by Chu et al. that the thermospheric Fe layers are produced through the neutralization of converged Fe+ layers. Through testing mechanisms and reproducing the 28 May 2011 event at McMurdo, we conceive the lifecycle of meteoric metals via deposition, transport, chemistry, and wave dynamics for thermospheric Fe layers with gravity wave signatures. While the meteor injection of iron species is negligible above 120 km, the polar electric field transports metallic ions Fe+ upward from their main deposition region into the E‐F regions, providing the major source of Fe+ (and accordingly Fe) in the thermosphere. Atmospheric wave‐induced vertical shears of vertical and horizontal winds converge Fe+ to form dense Fe+ layers. Direct electron‐Fe+ recombination is the major channel to neutralize Fe+ layers to form Fe above ~120 km. Fe layer shapes are determined by multiple factors of neutral winds, electric field, and aurora activity. Gravity‐wave‐induced vertical wind plays a key role in forming gravity‐wave‐shaped Fe layers. Aurora particle precipitation enhances Fe+ neutralization by increasing electron density while accelerating Fe loss via charge transfer with enhanced NO+ and O2+ densities.

Novel Experimental Simulations of the Atmospheric Injection of Meteoric Metals

A newly developed laboratory, Meteoric Ablation Simulator (MASI), is used to test model predictions of the atmospheric ablation of interplanetary dust particles (IDPs) with experimental Na, Fe, and Ca vaporization profiles. MASI is the first laboratory setup capable of performing time-resolved atmospheric ablation simulations, by means of precision resistive heating and atomic laser-induced fluorescence detection. Experiments using meteoritic IDP analogues show that at least three mineral phases (Na-rich plagioclase, metal sulfide, and Mg-rich silicate) are required to explain the observed appearance temperatures of the vaporized elements. Low melting temperatures of Na-rich plagioclase and metal sulfide, compared to silicate grains, preclude equilibration of all the elemental constituents in a single melt. The phase-change process of distinct mineral components determines the way in which Na and Fe evaporate. Ca evaporation is dependent on particle size and on the initial composition of the molten silicate. Measured vaporized fractions of Na, Fe, and Ca as a function of particle size and speed confirm differential ablation (i.e., the most volatile elements such as Na ablate first, followed by the main constituents Fe, Mg, and Si, and finally the most refractory elements such as Ca). The Chemical Ablation Model (CABMOD) provides a reasonable approximation to this effect based on chemical fractionation of a molten silicate in thermodynamic equilibrium, even though the compositional and geometric description of IDPs is simplistic. Improvements in the model are required in order to better reproduce the specific shape of the elemental ablation profiles.

Meteoric smoke and H2SO4 aerosols in the upper stratosphere and mesosphere

AbstractMeteoric smoke has traditionally been understood as a passive tracer which follows the global mesospheric circulation. Smoke extinction measured by the Solar Occultation For Ice Experiment, however, shows that while this is true in the middle to upper mesosphere (pressure <~0.2 hPa), it is not true near the stratopause. Here the expected winter increase begins 3 months earlier than in models. We suggest that the autumn extinction increase is due to H2SO4 condensing above the nominal stratospheric aerosol layer (~5 hPa). This is possible due to lowering of the H2SO4 saturation vapor pressure when the acid is neutralized through combination with meteoric metals. The appearance of neutralized H2SO4 aerosol in autumn is associated with the seasonal decrease in temperature. The combination of meteoric smoke and neutralized H2SO4 aerosols explains the observations and supports previous suggestions that H2SO4 could condense above the nominal stratospheric sulfate layer.

Solar cycle response and long-term trends in the mesospheric metal layers.

The meteoric metal layers (Na, Fe, and K)—which form as a result of the ablation of incoming meteors—act as unique tracers for chemical and dynamical processes that occur within the upper mesosphere/lower thermosphere region. In this work, we examine whether these metal layers are sensitive indicators of decadal long‐term changes within the upper atmosphere. Output from a whole‐atmosphere climate model is used to assess the response of the Na, K, and Fe layers across a 50 year period (1955–2005). At short timescales, the K layer has previously been shown to exhibit a very different seasonal behavior compared to the other metals. Here we show that this unusual behavior is also exhibited at longer timescales (both the ~11 year solar cycle and 50 year periods), where K displays a much more pronounced response to atmospheric temperature changes than either Na or Fe. The contrasting solar cycle behavior of the K and Na layers predicted by the model is confirmed using satellite and lidar observations for the period 2004–2013.

Correction to "Experimental Study of the Mesospheric Removal of NF3 by Neutral Meteoric Metals and Lyman-α Radiation".

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to “Experimental Study of the Mesospheric Removal of NF3 by Neutral Meteoric Metals and Lyman-α Radiation”Anna Totterdill, J.C. Gómez Martín, Tamás Kovács, Wuhu Feng, and John M.C. Plane*Cite this: J. Phys. Chem. A 2016, 120, 21, 3842Publication Date (Web):May 20, 2016Publication History Published online20 May 2016Published inissue 2 June 2016https://doi.org/10.1021/acs.jpca.6b04657Copyright © 2016 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views292Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (297 KB) Get e-Alerts Get e-Alerts

The near-global mesospheric potassium layer: Observations and modeling.

The meteoric metal layers act as unique tracers of chemistry and dynamics in the upper atmosphere. Existing lidar studies from a few locations show that K exhibits a semiannual seasonality (winter and summer maxima), quite unlike the annual seasonality (winter maximum and summer minimum) seen with Na and Fe. This work uses spaceborne observations made with the Optical Spectrograph and InfraRed Imager System instrument on the Odin satellite to retrieve the near‐global K layer for the first time. The satellite data (2004 to mid‐2013) are used to validate the implementation of a recently proposed potassium chemistry scheme in a whole atmosphere chemistry climate model, which provides a chemical basis for this semiannual seasonal behavior. The satellite and model data show that this semiannual seasonality is near global in extent, with the strongest variation at middle and high latitudes. The column abundance, centroid layer height, and root‐mean‐square width of the K layer are consistent with the limited available lidar record. The K data set is then used to investigate the impact of polar mesospheric clouds on the metal layers at high latitudes during summer. Finally, the occurrence frequency of sporadic K layers and their possible link to sporadic E layers are examined.

Mesospheric removal of very long-lived greenhouse gases SF6 and CFC-115 by metal reactions, Lyman-α photolysis, and electron attachment.

The fluorinated gases SF6 and C2F5Cl (CFC-115) are chemically inert with atmospheric lifetimes of many centuries which, combined with their strong absorption of IR radiation, results in unusually high global warming potentials. Very long lifetimes imply that mesospheric sinks could make important contributions to their atmospheric removal. In order to investigate this, the photolysis cross sections at the prominent solar Lyman-α emission line (121.6 nm), and the reaction kinetics of SF6 and CFC-115 with the neutral meteoric metal atoms Na, K, Mg, and Fe over large temperature ranges, were measured experimentally. The Na and K reactions exhibit significant non-Arrhenius behavior; quantum chemistry calculations of the potential energy surfaces for the SF6 reactions indicate that the Na and K reactions with SF6 are probably activated by vibrational excitation of the F-SF5 (v3) stretching mode. A limited set of kinetic measurements on Na + SF5CF3 are also presented. The atmospheric removal of these long-lived gases by a variety of processes is then evaluated. For SF6, the removal processes in decreasing order of importance are electron attachment, VUV photolysis, and reaction with K, Na, and H. For CFC-115, the removal processes in decreasing order of importance are reaction with O((1)D), VUV photolysis, and reaction with Na, K, and H.

Inferring the global cosmic dust influx to the Earth's atmosphere from lidar observations of the vertical flux of mesospheric Na

AbstractEstimates of the global influx of cosmic dust are highly uncertain, ranging from 0.4–110 t/d. All meteoric debris that enters the Earth's atmosphere is eventually transported to the surface. The downward fluxes of meteoric metals like mesospheric Na and Fe, in the region below where they are vaporized and where the majority of these species are still in atomic form, are equal to their meteoric ablation influxes, which in turn, are proportional to the total cosmic dust influx. Doppler lidar measurements of mesospheric Na fluxes made throughout the year at the Starfire Optical Range, New Mexico, (35°N) are combined with the Whole Atmosphere Community Climate Model predictions of the relative geographic variations of the key wave‐induced vertical transport processes to infer the global influxes of Na vapor and cosmic dust. The global mean Na influx is estimated to be 16,100 ± 3200 atoms/cm2/s, which corresponds to 278 ± 54 kg/d for the global input of Na vapor and 60 ± 16 t/d for the global influx of cosmic dust.

First global observations of the mesospheric potassium layer

AbstractMetal species, produced by meteoric ablation, act as useful tracers of upper atmosphere dynamics and chemistry. Of these meteoric metals, K is an enigma: at extratropical latitudes, limited available lidar data show that the K layer displays a semiannual seasonal variability, rather than the annual pattern seen in other metals such as Na and Fe. Here we present the first near‐global K retrieval, where K atom number density profiles are derived from dayglow measurements made by the Optical Spectrograph and Infrared Imager System spectrometer on board the Odin satellite. This robust retrieval produces density profiles with typical layer peak errors of ±15% and a 2 km vertical grid resolution. We demonstrate that these retrieved profiles compare well with available lidar data and show for the first time that the unusual semiannual behavior is near‐global in extent. This new data set has wider applications for improving understanding of the K chemistry and of related upper atmosphere processes.

Experimental study of the mesospheric removal of NF3 by neutral meteoric metals and Lyman-α radiation.

NF3 is a potent anthropogenic greenhouse gas with increasing industrial usage. It is characterized by a large global warming potential due in part to its large atmospheric lifetime. The estimated lifetime of about 550 years means that potential mesospheric destruction processes of NF3 should also be considered. The reactions of NF3 with the neutral metal atoms Na, K, Mg and Fe, which are produced by meteoric ablation in the upper mesosphere, were therefore studied. The observed non-Arrhenius temperature dependences of the reactions between about 190 and 800 K are interpreted using quantum chemistry calculations of the relevant potential energy surfaces. The NF3 absorption cross section at the prominent Lyman-α solar emission line (121.6 nm) was determined to be (1.59 ± 0.10) × 10(-18) cm(2) molecule(-1) (at 300 K). In the mesosphere above 60 km, Lyman-α photolysis is the dominant removal process of NF3; the reactions with K and Na are 1-2 orders of magnitude slower. However, the atmospheric lifetime of NF3 is largely controlled by reaction with O((1)D) and photolysis at wavelengths shorter than 190 nm; these processes dominate below 60 km.

Micrometer‐ and nanometer‐sized platinum group nuggets in micrometeorites from deep‐sea sediments of the Indian Ocean

Abstract– We examined 378 micrometeorites collected from deep‐sea sediments of the Indian Ocean of which 175, 180, and 23 are I‐type, S‐type, and G‐type, respectively. Of the 175 I‐type spherules, 13 contained platinum group element nuggets (PGNs). The nuggets occur in two distinct sizes and have distinctly different elemental compositions: micrometer (μm)‐sized nuggets that are >3 μm contain dominantly Ir, Os, and Ru (iridium‐platinum group element or IPGE) and sub‐μm (or nanometer)‐sized (<1 μm) nuggets, which contain dominantly Pt, Rh, and Pd (palladium—PGE or PPGE). The μm‐sized nuggets are found only one per spherule in the cross section observed and are usually found at the edge of the spherule. By contrast, there are hundreds of nanometer‐sized nuggets distributed dominantly in the magnetite phases of the spherules, and rarely in the wüstite phases. Both the nugget types are found as separate entities in the same spherule and apparently, nugget formation is a common phenomenon among I‐type micrometeorites. However, the μm‐sized nuggets are seen in fewer specimens (∼2.5% of the observed I‐type spherules). In all, we analyzed four nuggets of μm size and 213 nanometer‐sized nuggets from 13 I‐type spherules for platinum group elements. Chemically, the μm‐sized PGNs contain chondritic ratios of Os/Ir, but are depleted in the more volatile PGE (Pt, Rh, and Pd) relative to chondritic ratios. On the other hand, the nanometer‐sized nuggets contain dominantly Pt and Rh. Importantly, the refractory PGEs are conspicuous by their absence in these nanometer nuggets. Palladium, the most volatile PGE is highly depleted (<1.1%) with respect to chondritic ratios in the μm‐sized PGNs, and is observed in only 17 of 213 nanometer nuggets with concentrations that are just above the detection limit (≥0.2%). Distinct fractionation of the PGE into IPGE (Ir, Os, Ru) and PPGE seems to take place during the short span of atmospheric entry. These observations suggest several implications: (1) The observation of fractionated PGE in an Fe‐Ni system gives rise to the possibility that Earth’s core could contain fractionated PGE. (2) The present data support the processes suggested for the fractionated PGE patterns observed in the ejecta of ancient meteorite impacts. (3) Meteoric metals released in the troposphere could contain fractionated PGNs in large numbers.

Global column density retrievals of mesospheric and thermospheric Mg I and Mg II from SCIAMACHY limb and nadir radiance data

The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography instrument (SCIAMACHY) instrument exhibits useful observational abilities to separate meteoric metal total content within different levels of the atmosphere. In this work, we present an algorithm to give the total content and to separate the total column into two partial columns in the thermosphere and the mesosphere, using measurements of resonant radiation by the SCIAMACHY instrument. Limb and nadir measurements are used. The results presented here constitute the first simultaneous measurements of mesospheric and thermospheric column densities including the successful separation of same. We present column density measurements of Mg II and Mg I in the mesosphere and the thermosphere and the total content. The data set considered here covers the latitude range from 80°S to 80°N and covers the time range from 2002 to 2006. Measurements are taken on a global scale to investigate seasonal and spatial variations. Total columns range from 107 to 1010 cm−2, in good agreement with previous satellite measurements and model calculations. The temporal evolution of both Mg I species is investigated over the time range from mid‐2002 until the end of 2006. A pronounced minimum in 2003 and a subsequent increase until 2006 are observed for the ionized species. The global distribution of both Mg I and Mg II is found to be seasonally varying, exhibiting maximum column densities within the summer hemisphere. No significant correlation with the solar activity is found. Increased abundances of Mg II are observed within regions of high geomagnetic activity (i.e., the northern and southern auroral ovals) only if the background abundance of Mg II is low. It is concluded that the increase of Mg II due to particle impact is a minor effect.

Seasonal variations of magnesium atoms in the mesosphere‐thermosphere

UV radiances from the Global Ozone Monitoring Experiment (GOME) spectrometer on the ERS‐2 satellite are used to determine long‐term dayside temporal variations of the total vertical column density below 795 km of the meteoric metal species Mg and Mg+ in the upper atmosphere. The GOME instrument has the ability to observe the ground state transition lines of Mg I at 285.2 nm and resolve the Mg II at 280 nm. A retrieval algorithm has been developed to determine column densities and applied to the years 1996–1997. Results show the middle latitude dayside Mg+ peaks in total vertical content during the summer, while neutral Mg demonstrates a much more subtle maximum in summer. Dayside trends are opposite previous midlatitude nighttime lidar observations, with the exception of calcium. The Mg+/Mg ratio has a seasonal variation, reaching a maximum in the summer. The total content of Mg+ is twice that of neutral Mg.

Simultaneous observations of sporadic Fe and Na layers by two closely colocated resonance fluorescence lidars at Wuhan (30.5°N, 114.4°E), China

The focus of this paper is to study the relationship between sporadic Fe (Fes) and Na (Nas) layers through simultaneous and common volume Fe and Na lidar observations. A total of 37 sporadic layering events were identified from one year (195 hours) of observations at Wuhan (30.5°N, 114.4°E), China. Out of the 37 events, 23 (62%) are characterized by the simultaneous formation of Fes and Nas layers. The most prominent feature for each of the 23 events is that the Fes and Nas layers occurred in overlapping altitude ranges and moved following almost the same track. On occasion the Fes and Nas layers exactly simultaneously reached their maximum peak densities at nearly the same altitude. These observational results strongly suggest that Fes and Nas layers are formed via the same or very similar mechanisms. This conclusion contradicts the previous suggestion based on those independent observations of Fes and Nas layers, that the Fes and Nas layers may be formed via different mechanisms. Out of the 37 events, 14 (38%) belong to single‐species sporadic layering events. It is noticed that the formation of each single‐species sporadic atom layer was usually accompanied by a weak density enhancement in the other metal atom. This supports the suggestion that Fes and Nas layers are formed via the same or very similar mechanisms. Both the Fes and Nas layers over Wuhan showed a tendency to strengthen with decreasing occurrence altitude. This tendency is consistent with the earlier Nas layer observations at high and low latitudes. Moreover, it is noticed by comparing the currently available Fes and Nas layer characteristics, which came from the observations at five different locations (including Wuhan) during different periods, that a lower average altitude could link to a higher average peak density and vice versa. The statistics‐based link might perhaps represent a universal feature of sporadic layers. From our simultaneous Fe and Na density data we have found that the undersides of the normal Fe and Na layers follow nearly the exact movements and occur at nearly the same altitude. The normal Fe layer tended to be narrower than the corresponding Na layer nearly at all times, and this difference was generally reflected in the extent of the upper edge of the layer. The nearly persistent underside overlap strongly suggests that on the undersides of these meteoric metal layers there exist some sink mechanisms leading to the concurrent removal of different sorts of free neutral metal atoms.

Carbonaceous material in aerosol particles in the lower stratosphere and tropopause region

The Particle Analysis by Laser Mass Spectrometry (PALMS) instrument has measured the composition of single particles in the lower stratosphere. The average fraction of carbonaceous material in the stratospheric particles decreased rapidly above the tropopause. The decrease in the average carbon content was mostly associated with a sharp increase in the bottom 2 km of the stratosphere in the frequency of fairly pure sulfate particles both with or without meteoric metals. The low potassium content of the fairly pure sulfate particles is used to show that they were formed in the stratosphere and were not tropospheric particles that had lost organics because of oxidation. Of the tropospheric carbonaceous‐sulfate particles found in the stratosphere, the mass spectra had similar patterns from the upper troposphere to the maximum altitude sampled, about 19 km. A reduction in the carbon to sulfate ratio in tropospheric particles was only apparent above about 440 K potential temperature. This implies that carbon compounds can remain for months in particles larger than about 300 nm. Despite the slow rate, these data do not exclude rapid heterogeneous reactions of organics in the particles with OH or other radicals. There was no evidence of significant transfer of semivolatile organics between particles in the stratosphere. However, particles that originated in the stratosphere acquired small amounts of carbon when they were transported to the tropopause.