Earth's Stratosphere Research Articles

Flying microbes-survival in the extreme conditions of the stratosphere during a stratospheric balloon flight experiment.

Earth's stratosphere is a hostile environment that has challenged microbial survival. We set out to test the effect of stratosphere exposure on survival of single species (Bacillus subtilis) and complex microbial communities from soils and sediment. B. subtilis survival was strongly impacted by sun exposure, i.e., ultraviolet (UV) radiation, with only 1% survival at full sun exposure. Complex microbial communities had high survival rates, and the soil or sediment matrix may have provided protection against radiation and desiccation, supporting the survival of environmental microorganisms.

Modeling and characterization of gas coupled ultrasonic transducers at low pressures and temperatures and implications for sonic anemometry on Mars.

A sonic anemometer targeted at wind speed measurements on the surface of Mars is described. This environment requires transducer operation in 4-10 mbar CO2 at temperatures between 143 and 293 K (-130 °C and 20 °C, respectively). Over these ranges, transducer pressure and temperature sensitivity could be a source of measurement error. To investigate this, four candidate transducers were tested using transmission mode ultrasonic testing and impedance measurements: two narrowband piezoelectric transducers, a broadband capacitive transducer, and a micromachined capacitive ultrasound transducer. A system model was used for comparison and interpretation, and implications for a sonic anemometer were examined. Variation of transducer characteristics, including diffraction effects, across 2-10 mbar in CO2 and 190-293 K (-83 °C-20 °C) result in ±2.3% error in wind speed measurement and ±1.1% error in speed of sound measurement for the worst case but only ±0.14% error in wind and ±0.07% error in speed of sound for the best transducer operated off resonance. The acoustic conditions on Mars are similar to those in Earth's stratosphere at 30-42 km of altitude. Hence, testing was also conducted in dry air over the same range of pressures and temperatures with relevance to a secondary application of the instrument as a stratospheric anemometer for high altitude balloon missions on Earth.

High-altitude balloon platform for studying the biological response of living organisms exposed to near-space environments

The intangible desire to explore the mysteries of the universe has driven numerous advancements for humanity for centuries. Extraterrestrial journeys are becoming more realistic as a result of human curiosity and endeavors. Over the years, space biology research has played a significant role in understanding the hazardous effects of the space environment on human health during long-term space travel. The inevitable consequence of a space voyage is space ionizing radiation, which has deadly aftereffects on the human body. The paramount objective of this study is to provide a robust platform for performing biological experiments within the Earth's stratosphere by utilizing high-altitude balloons. This platform allows the use of a biological payload to simulate spaceflight missions within the unique properties of space that cannot be replicated in terrestrial facilities. This paper describes the feasibility and demonstration of a biological balloon mission suitable for students and scientists to perform space biology experiments within the boundary of the stratosphere. In this study, a high-altitude balloon was launched into the upper atmosphere (∼29 km altitude), where living microorganisms were exposed to a hazardous combination of UV irradiation, ultralow pressure and cold shock. The balloon carried the budding yeast Saccharomyces cerevisiae to investigate microbial survival potential under extreme conditions. The results indicated a notable reduction in biosample mortality two orders of magnitude (2-log) after exposure to 164.9 kJ m−2 UV. Postflight experiments have shown strong evidence that the effect of UV irradiation on living organisms is stronger than that of other extreme conditions.

Experimental correlation of natural convection in low Rayleigh atmospheres for vertical plates and comparison between CFD and lumped parameter analysis

This paper offers a comprehensive exploration of thermal analysis for space systems operating in low Rayleigh atmospheres, with a primary focus on enhancing the accuracy and reliability of convective heat transfer modeling. The study centers around an analysis of a vertical heated plate experiment, where a lumped parameter model is employed to encompass conductive, radiative, and convective heat transfer mechanisms. To advance the accuracy of convective heat transfer coefficient calculations, this paper introduces a novel approach involving the utilization of Nusselt number correlations. These correlations are developed through an analytical solution derived from the Navier-Stokes equations, tailored specifically for the internal natural convection problem. This approach treats convection as a heat exchange process between the heated plate and the surrounding air, thereby improving the precision of modeling internal convection within a lumped parameter framework. A specific correlation (González-Bárcena et al.) is obtained for the proposed problem, derived from experimental tests conducted in a thermal vacuum chamber, under varying pressure conditions to control the Rayleigh number. Additionally, the findings are validated using Computational Fluid Dynamics (CFD) tools to calculate the velocity and temperature fields within the cavity. The González-Bárcena et al. correlation significantly enhances temperature predictions, demonstrating an improvement of up to 10∘C when compared to conventional literature correlations. The methodology presented in this paper holds promise for extension to more complex experiments in low Rayleigh atmospheres, including those conducted in the Earth's stratosphere or on the Martian surface, thereby contributing to the advancement of thermal analysis in challenging space environments.

Evidence of rapid hydrogen chloride uptake on water ice in the atmosphere of Mars

In 2020, hydrogen chloride (HCl) in the gas phase was discovered in the atmosphere of Mars with the Atmospheric Chemistry Suite (ACS) onboard the Trace Gas Orbiter (TGO) mission (Korablev et al., 2021). Its volume mixing ratio (VMR) shows a seasonal increase of up to 5 ppbv during the perihelion season, followed by a sudden drop to undetectable levels, contradicting modelling estimates of the HCl lifetime of several months. In the Earth's stratosphere, heterogeneous uptake of HCl onto water ice is known to be a major sink for this species. This reaction is now also considered when modelling HCl abundances in the Martian atmosphere. In this work, we use simultaneous measurements of water ice and HCl obtained by the ACS instrument to find particular structures in the vertical profiles as detached gas layers at ice-free altitudes (“ice-holes”). From these particular examples we conclude that the heterogeneous uptake of HCl onto water ice operates on Mars and is a fast mechanism regulating the HCl abundance in the atmosphere of Mars.

The Matsuno–Gill model on the sphere

We extend the Matsuno–Gill model, originally developed on the equatorial $\beta$ -plane, to the surface of the sphere. While on the $\beta$ -plane the non-dimensional model contains a single parameter, the damping rate $\gamma$ , on a sphere the model contains a second parameter, the rotation rate $\epsilon ^{1/2}$ (Lamb number). By considering the different combinations of damping and rotation, we are able to characterize the solutions over the $(\gamma, \epsilon ^{1/2})$ plane. We find that the $\beta$ -plane approximation is accurate only for fast rotation rates, where gravity waves traverse a fraction of the sphere's diameter in one rotation period. The particular solutions studied by Matsuno and Gill are accurate only for fast rotation and moderate damping rates, where the relaxation time is comparable to the time on which gravity waves traverse the sphere's diameter. Other regions of the parameter space can be described by different approximations, including radiative relaxation, geostrophic, weak temperature gradient and non-rotating approximations. The effect of the additional parameter introduced by the sphere is to alter the eigenmodes of the free system. Thus, unlike the solutions obtained by Matsuno and Gill, where the long-term response to a symmetric forcing consists solely of Kelvin and Rossby waves, the response on the sphere includes other waves as well, depending on the combination of $\gamma$ and $\epsilon ^{1/2}$ . The particular solutions studied by Matsuno and Gill apply to Earth's oceans, while the more general $\beta$ -plane solutions are only somewhat relevant to Earth's troposphere. In Earth's stratosphere, Venus and Titan, only the spherical solutions apply.

Ozone Therapy in Periodontics: A Review

Oral cavity is in dynamic interaction with external environment exposing it to various microorganisms their colonization and the host defense that aimed for their removal. Formation and development of dental biofilm and its potential to harbor specific microorganisms is directly linked with some of the most common oral ailments like dental caries diseases affecting periodontium. The conventional protocol to treat such ailments primarily include removal of biofilm along with adjunctive course of antibiotics. However these modalities have limitations in their efficacy. Ozone is a natural gas present in the earth stratosphere and acts as a potent oxidant. At low doses ozone has several favorable therapeutic applications in medicine as well as in dental pathologies. Particularly ozone as a treatment modality was used for the first time in dentistry in the 1930s when it was proposed as a disinfectant and wound-healing agent. Owing to its strong oxidation property with the formation of free radicals and its capacity to directly destruct almost all microorganisms it is known as a potential antioxidant anti-inflammatory immunomodulatory anti-hypoxic biosynthetic and antimicrobial agent. In addition ozone has a therapeutic effect that promotes wound healing and improves blood supply. Three most common forms in which ozone can be administered for its therapeutic use are gaseous aqueous and oil forms out of which the gaseous application of ozone is critically evaluated because of its possible side effects on the respiratory system. The objective of the current article was to compile and document various application of ozone in the field of periodontology. Research was based on peer-reviewed sources found through MedlinePubMed Google scholar search and other reviews and journals.

Fluid Dynamics of Polar Vortices on Earth, Mars, and Titan

Polar vortices that share many similarities are found in Earth's stratosphere and the atmospheres of Mars and Saturn's moon Titan. These vortices all occur in the winter, and are characterized by high potential vorticity (PV) in polar regions, steep meridional PV gradients and peak zonal winds in middle latitudes, and a cold pole. There are, however, differences in the daily and subseasonal variability, zonal asymmetries, and PV structure among the vortices. These differences are related to differences in the disruption of polar vortices by Rossby waves, the poleward extent of the mean meridional circulation, and condensation of major gases. There are also differences in the transport of gases and particles among the vortices. The range of polar vortex characteristics is likely much larger for terrestrial exoplanets, which include planets with, for example, a wider range of obliquities.

Atmospheric Overturning Circulation on Dry, Tidally Locked Rocky Planets Is Mainly Driven by Radiative Cooling

In this study, we examine the driving mechanism for the atmospheric overturning circulation on dry, tidally locked rocky planets without the condensation of water vapor or other species. We find that the main driving process is the radiative cooling of CO2 (or other noncondensable greenhouse gases) rather than CO2 greenhouse warming or stellar radiation. Stellar radiation is the ultimate mechanism but not the direct mechanism. Due to the combination of the uneven distribution in the stellar radiation and effective horizontal energy transports in the free troposphere, there is strong temperature inversion in the area away from the substellar region. This inversion makes CO2 have a radiative cooling effect rather than a radiative warming effect for the atmosphere, the same as that in the stratosphere of Earth’s atmosphere. This cooling effect produces negative buoyancy and drives large-scale downwelling, supporting the formation of a global-scale overturning circulation. If CO2 is excluded from the atmosphere, the overturning circulation becomes very weak, regardless of the level of stellar radiation. This mechanism is completely different from that for the atmospheric overturning circulation on Earth or on moist, tidally locked rocky planets, where latent heat release and/or baroclinic instability are the dominated mechanisms. Our study improves the understanding of the atmospheric circulation on tidally locked exoplanets and also on other dry planets, such as Venus and Mars in the solar system.

Waves on the equatorial β-plane in the presence of a uniform zonal flow: Beyond the Doppler shift

Analytical and numerical solutions of the eigenvalue equation associated with zonally propagating waves of the linearized rotating shallow water equations are derived in a channel on the equatorial β-plane in the presence of a uniform mean zonal flow. The meridionally varying mean height field is in geostrophic balance with the prescribed mean zonal flow. In addition to the trivial Doppler shift of the free waves' phase speeds, the mean state causes the dispersion curves of each of the free Rossby and Poincaré waves to nearly coalesce in pairs of modes when the zonal wavenumber increases. For large zonal wavenumber or large mean flow, the latitudinal variation of the waves' amplitudes differs from that of free waves, i.e., Hermite functions (in wide channels) and harmonic functions (in narrow channels) do not describe the amplitude structure. For large mean speed and for large zonal wavenumber, the eigenvalue problem loses its Sturm–Liouville structure and the eigenfunctions have multiple extrema between successive zeros of the function itself. In contrast to free Kelvin waves, in the presence of a mean flow the meridional velocity component of these waves does not vanish identically. For zonal winds of order 20 m s−1 and for gravity wave speed of order 25 m s−1, conditions relevant to Earth's stratosphere, the phase speed with mean wind can be twice that of the classical theory with no mean zonal wind.

АЕРОНОМІЧНА РАДІОСПЕКТРОМЕТРІЯ З КАЛІБРУВАННЯМ ЗА ВІРТУАЛЬНИМИ ДЖЕРЕЛАМИ

Subject and Purpose. The work has been aimed at developing and implementing a novel method of aeronomic observations in the Earth's stratosphere, applicable in the microwave range of the electromagnetic spectrum. The research is centered on a study of the measurement errors arising when the method proposed is employed for observations of the ozone spectral line (142 GHz). Methods and Methodology. The method is based on a simplified calibration procedure, in what concerns the hardware and the technology employed. In contrast to the common calibration techniques using special-purpose sources of the reference signal, we suggest resorting to natural sources, like internal noise of the receiver and the thermal radiation from the Earth's surface and the lower atmospheric layer. The measurement errors (both calculated and evaluated experimentally) have been analyzed within standard mathematical statistics techniques. Results. The tests performed during observations of the spectral line (142 GHz) of atmospheric ozone allow considering the new method as a success. The estimated magnitude of the relative error specific to the observation method proposed does not exceed 1.5%. The experimental estimate accounting for all potential error sources does not exceed 5% (with a 1 hour accumulation period), which result corresponds to the current state of the art. Conclusions. The possibility of an essential simplification of the radio optical part of the spectrometer has been demonstrated. The novel calibration technique, as well as the technical implementation thereof, can be recommended as a basis for prospective spectrometers at microwave frequencies.

Oxygen isotope systematics of crystalline silicates in a giant cluster IDP: A genetic link to Wild 2 particles and primitive chondrite chondrules

Anhydrous interplanetary dust particles (IDPs) collected from Earth's stratosphere are the most primitive extraterrestrial materials that likely are the remnants of major building blocks of our solar system. While they probably originated from icy outer solar system comets, this hypothesis needs to be further verified via comparison with Wild 2 (a Jupiter-family comet) particles returned by the Stardust mission. Besides, the origins of their components can be further constrained by comparing with materials in primitive chondrite. Here we investigate the petrology and oxygen isotope systematics of 20 fragments extracted from a giant cluster IDP U2-20GCA. Fifteen are monomineralic or polymineralic fragments composed of olivine and/or pyroxene. Others are plagioclase/glass bearing fragments similar to barred-olivine chondrules, enstatite-rich chondrules, and Al-rich chondrules (ARC). They show a range of Mg# [mol% Mg/(Mg+Fe)] in olivine and pyroxene (99-75) and MnO and Cr2O3 abundances in olivine that resemble Wild 2 particles. Individual fragments have relatively 16O-poor oxygen isotope ratios with δ18O and δ17O varying from −6.2±1.0‰ to 6.8±1.9‰ and −6.7±2.6‰ to 5.3±1.2‰, respectively. Most fragments show Δ17O (=δ17O-0.52×δ18O) increasing from ∼−3‰ to ∼0‰ with decreasing Mg#, similar to those observed in Wild 2 particles and CR chondrite chondrules. Four fragments (including the ARC-like fragment) show oxygen isotope signatures of ordinary (O), R, or CH-CB chondrite chondrules. The similarities among the giant cluster IDP, Wild 2 particles, and primitive chondrite chondrules demonstrate (i) a cometary origin of anhydrous IDPs; (ii) the major source of crystalline silicates in comets is likely to be CR chondrite chondrule-like materials, while minor sources include O, R, or CH-CB chondrite chondrule-like materials. The conclusions support the hypothesis that anhydrous IDPs sampled extremely heterogeneous materials formed in wide solar system regions like Wild 2 particles.

On the Holton–Lindzen–Plumb model for mean flow reversals in stratified fluids

AbstractThe Holton–Lindzen–Plumb (HLP) model describes the spontaneous emergence of mean flow reversals in stratified fluids. It has played a central role in understanding the Quasi‐Biennial Oscillation of equatorial winds in Earth's stratosphere and has arguably become a linchpin of wave–mean flow interaction theory in geophysical and astrophysical fluid dynamics. The derivation of the model's equation from primary equations follows from several assumptions, including quasi‐linear approximations, WKB expansion of the wavefield, simplifications of boundary‐layer terms, among others. Starting from the two‐dimensional, non‐rotating, Boussinesq equations, we present in this paper a self‐consistent derivation of the HLP model and show the existence of a distinguished limit for which all approximations remains valid. We furthermore discuss the important role of boundary conditions, and the relevance of this model to describe secondary bifurcations associated with a quasi‐periodic route to chaos.

Radiometric Stability of the SABER Instrument

AbstractThe SABER instrument on the National Aeronautics and Space Administration Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics satellite continues to provide a long‐term record of Earth's stratosphere, mesosphere, and lower thermosphere. The SABER data are being used to examine long‐term changes and trends in temperature, water vapor, and carbon dioxide. A tacit, central assumption of these analyses is that the SABER instrument radiometric calibration is not changing with time; that is, the instrument is stable. SABER stratospheric temperatures and those derived from Global Positioning System Radio Occultation measurements are compared to examine SABER's stability. Global Positioning System Radio Occultation measurements are inherently stable due to the accuracy and traceability of the measured phase delay rate to the Système Internationale definition of the second. Differences in global annual mean SABER and COSMIC lower stratospheric temperatures show little significant change with time in the 11 years spanning 2007–2017. From this analysis we infer that SABER temperatures are stable to better than 0.1 to 0.2 K per decade.

Earth's Stratosphere and Microbial Life

The Earth's atmosphere is an extremely large and sparse environment which is quite challenging for the survival of microorganisms. We have long wondered about the limits to life in the atmosphere, starting with Leeuwenhoek's observation of "animalcules" collected from the air. In the past century, significant progress has been made to capture and identify biological material from varying elevations, from a few meters above ground level, to the clouds near mountaintops, and the jet streams, the ozone layer, and even higher up in the stratosphere. Collection and detection techniques have been developed and advanced in order to assess the potential diversity of life from very high altitudes. Studies of microbial life in the stratosphere with its multiple stressors (cold, dry, irradiated, with low pressure and limited nutrients), have recently garnered considerable attention. Here, we review studies of Earth's atmosphere, with emphasis on the stratosphere, addressing implications for astrobiology, the dispersal of microbes around our planet, planetary protection, and climate change.

Study of the possibility of steady horizontal flight of the dual aircraft platform with the wind shear

In the first part of paper accurate and approximate solution for the equation of motion of steady horizontal flight for dual-aircraft platform (DAP) was given. The two gliders (sailplanes) fly at different heights and connected by a tether. To perform a horizontal flight only the effect of wind shear is used. Minimum of platform velocity to cross wind shear ratio was founded. In the second part of paper overview airflow for troposphere and stratosphere of Earth was given. Wind velocity profile was investigated for some random places. Opportunity of flight without engine was approved. However it is possible at specific conditional only.

Extremophilic models for astrobiology: haloarchaeal survival strategies and pigments for remote sensing.

Recent progress in extremophile biology, exploration of planetary bodies in the solar system, and the detection and characterization of extrasolar planets are leading to new insights in the field of astrobiology and possible distribution of life in the universe. Among the many extremophiles on Earth, the halophilic Archaea (Haloarchaea) are especially attractive models for astrobiology, being evolutionarily ancient and physiologically versatile, potentially surviving in a variety of planetary environments and with relevance for in situ life detection. Haloarchaea are polyextremophilic with tolerance of saturating salinity, anaerobic conditions, high levels of ultraviolet and ionizing radiation, subzero temperatures, desiccation, and toxic ions. Haloarchaea survive launches into Earth's stratosphere encountering conditions similar to those found on the surface of Mars. Studies of their unique proteins are revealing mechanisms permitting activity and function in high ionic strength, perchlorates, and subzero temperatures. Haloarchaea also produce spectacular blooms visible from space due to synthesis of red-orange isoprenoid carotenoids used for photoprotection and photorepair processes and purple retinal chromoproteins for phototrophy and phototaxis. Remote sensing using visible and infrared spectroscopy has shown that haloarchaeal pigments exhibit both adiscernable peak of absorption and a reflective"green edge". Since the pigments produce remotely detectable features, they may influence the spectrum from an inhabited exoplanet imaged by a future large space-based telescope. In this review, we focus primarily on studies of two Haloarchaea, Halobacterium sp. NRC-1 and Halorubrum lacusprofundi.

Photophoresis of aerosol particles with nonuniform gas–surface accommodation in the free molecular regime

The problem of calculating the photophoretic force acting on an aerosol particle, with nonuniform distributions of accommodation coefficients over the particle's surface in a rarified equilibrium gas medium in the free molecular regime, is considered within the framework of perturbation theory, using the assumption that the variations of accommodation coefficients are sufficiently small. In general, the expression for the force acting on a convex particle involves four contributions. The energy accommodation coefficient and the radiometric accommodation coefficient for normal momentum are used.The formulae for calculating all four contributions to the photophoretic force are presented for a uniform spherical particle with finite thermal conductivity and a nonuniform axisymmetric distribution of accommodation coefficients over its surface. According to our estimates, the photophoretic force is defined with good accuracy by only two contributions: the “delta-alpha” force and “delta-T” force. The other contributions are small corrections to these two prevailing forces of order 1% or less.The ratio between the “delta-alpha” and “delta-T” forces depends on the particle size, Knudsen number, and the differences in the accommodation coefficients. For micron-sized spherical particles, the photophoretic “delta-alpha” force exceeds the “delta-T” force, and also exceeds gravity if the variation in the radiometric accommodation coefficient over the particle's surface is more than 0.055. Thus, levitation of particles in the Earth's stratosphere is possible due to gravito-photophoresis. For centimetre-sized particles, the “delta-T” force is a few orders of magnitude larger than the “delta-alpha” force due to the influence of IR radiation on the particles' temperature.

Diagnostics of internal atmospheric wave saturation and determination of their characteristics in Earth's stratosphere from radiosonde measurements

Internal gravity waves (IGW) significantly affect the structure and circulation of Earth’s atmosphere by transporting wave energy and momentum upward from the lower atmosphere. Since IGW can propagate freely through a stably stratified atmosphere, similar effects may occur in the atmospheres of Mars and Venus. Observations of temperature and wind speed fluctuations induced by internal waves in Earth’s atmosphere have shown that wave amplitudes increase with height, but not quickly enough to correspond to the amplitude increase due to an exponential decrease in the density without energy dissipation. The linear theory of IGW explains the wave amplitude growth rate as follows: any wave amplitude exceeding the threshold value leads to instability and produces turbulence, which hinders further amplitude growth (internal wave saturation). The mechanisms that contribute most to the energy dissipation and saturation of IGW in the atmosphere are thought to be the dynamical (shear) and convective instabilities. The assumption of internal wave saturation plays a key role in radio occultation monitoring of IGW in planetary atmospheres. A radiosonde study of wave saturation processes in Earth’s atmosphere is therefore actual and important task. We report the results of determination of actual and threshold amplitudes, saturation degree, and other characteristics for the identified IGW in Earth’s atmosphere obtained from the analysis of SPARC (Stratospheric Processes And their Role in Climate) radiosonde measurements of wind speed and temperature [http://www.sparc.sunysb.edu/].

A Near‐Global Atmospheric Distribution of N2O Isotopologues

AbstractThe distributions of the four most abundant isotopologues and isotopomers (N2O, 15NNO, N15NO, and NN18O) of nitrous oxide have been measured in the Earth's stratosphere by infrared remote sensing with the Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer. These satellite observations have provided a near‐global picture of N2O isotopic fractionation. The relative abundances of the heavier species increase with altitude and with latitude in the stratosphere as the air becomes older. The heavy isotopologues are enriched by 20–30% in the upper stratosphere and even more over the poles. These observations are in general agreement with model predictions made with the Whole Atmosphere Community Climate Model (WACCM). A detailed 3‐D chemical transport model is needed to account for the global isotopic distributions of N2O and to infer sources and sinks.