An Introduction to Meteorics

With the term meteor we characterize all phenomena that occur when a body from space enters the Earth’s atmosphere; the body or its fragments are called meteoroids or, if they happen to land on the Earth’s surface, meteorites.

Peroxy radicals (HO2, RO2) are important intermediates in Earth's atmosphere. They are intermediates in the oxidation of alkanes and CO in combustion and atmospheric chemical processes. In earth's atmosphere, the rates of their self and cross reactions are often the dominant loss processes when NOx concentrations fall below tens of pptv. These reactions have proven difficult to study in laboratory experiments, due to complex secondary chemistry and ambiguities in radical detection. This thesis describes a new laser-photolysis apparatus to measure the rates of peroxy radical reactions under atmospheric conditions that employs simultaneous UV direct absorption and IR wavelength-modulation spectroscopy to detect the peroxy radicals. Prior kinetic measurements of gas-phase peroxy radical reactions have typically employed flash-photolysis methods coupled with detection of the radicals only by UV absorption spectroscopy. However, uncertainties can arise because several different species often contribute to the absorption signal. The IR channel provides an independent means of monitoring HO2 radicals by detection of specific rovibrational transitions. With this apparatus, the rates of the reactions HO2 + NO2, HO2 + CH3O2, CH3O2 + CH3O2, and HO2 + HO2 were studied at temperatures from 219 K to 300 K. Our measurements have, in some cases, led to significant revision of previously accepted rate constants, mechanisms, or product yields, especially at conditions relevant to the upper atmosphere. The new rate coefficients for the HO2 + HO2 reaction are shown to account for a long-standing discrepancy in modeled vs. observed hydrogen peroxide in the stratosphere. A key finding has been the observation that many previous measurements of HO2 reactions at low temperatures have suffered from problems due to complexation between HO2 and methanol, a precursor used to generate HO2. Direct kinetic evidence is presented for the formation of the HO2?CH3OH complex; the rate coefficients, equilibrium constant, and enthalpy of reaction for HO2 + CH3OH HO2?CH3OH were measured. These results are the first direct study of the chaperone effect proposed to explain the enhancement of the observed rates of the HO2 self-reaction by hydrogen-bonding species. The effects of methanol enhancement on the HO2 + NO2, HO2 + CH3O2, CH3O2 + CH3O2, and HO2 + HO2 reaction rates were measured. For the HO2 + NO2 reaction, overlapping, time-dependent signals in the UV due to the equilibrium between NO2 and N2O4 were observed that may not have been properly accounted for in previous measurements. Other studies of NO2 reactions conducted at temperatures below 250 K may be subject to similar errors. In the CH3O2 + CH3O2 reaction, detection of HO2 products has raised questions concerning the product yields and reaction mechanisms.

It has been recently definitively established that the development of Extensive Air Showers (EAS) which are induced in the Earth's atmosphere by impinging cosmic particles from the outermost space is accompanied by the emission of radio waves. This phenomenon is experimentally investigated by the LOPES experiment, co-located at Karlsruhe Institute of Technology (KIT) with the EAS detector array KASCADE-Grande using traditional detection techniques. The LOPES experiment is an absolutely amplitude calibrated array of radio antennae for observing radio waves from EAS in the frequency range of 40-80~MHz. The KASCADE-Grande array provides the trigger information and experimentally determined parameters of the associated EAS observed in the energy range of $10^{16}-10^{18}$~eV. The studies are focussed to understand and clarify the phenomena of EAS radio emission, in particular in view of an eventual large scale application of a corresponding detection technique, like in LOFAR (Low Frequency Array for which LOPES is a prototype station) and for the Pierre Auger Observatory. Until summer 2006, all 30 antennas were equipped in the east-west polarization direction only, measuring a single polarization of the radio emission. The data of this LOPES set-up provided the possibility for a detailed investigation of correlations of the radio signal with basic EAS parameters like arrival direction, particle energy and mass of the primary. The results enable studies of the radio signal on a single EAS event basis, in particular of its lateral extension. Nevertheless, the north-south polarization component is required for an improved understanding of the radio emission signal and for a verification of the geo-synchrotron effect as the dominant mechanism of radio emission in air showers. The focus of the present work are measurements and analyses of the polarization of the radio signals from EAS. Investigations of the radio pulse height in correlation with EAS parameters, including an adequate parametrization of the pulse height per single polarization in east-west and north-south direction, respectively, have been performed. The studies of the lateral distribution per single event and per single polarization of the electric field are helpful for an improved understanding of the shower development. The polarization vector was finally reconstructed by observations with dual polarization antennae which are configured for both polarizations of signals recorded at the same place and simultaneously for the east-west and north-south direction. Comparisons with theoretical studies complete the investigations. The geo-synchrotron emission process is confirmed as the radio emission mechanism in cosmic ray air showers. In addition, it could be found that a not negligib le contribution to the total signal stems from another emission process. It is most probably induced by the negative charge excess during the shower development. This contribution mainly modifies the North-South polarization component of the dominant geo-synchrotron induced signal.

The widely used coordinate system (B,L) has proved very suitable for most of the region covered by the Van Allen belts, but is not very well suited for the low‐altitude regions where the Earth’s atmosphere interacts with the trapped particle population. Several alternative coordinate systems have been proposed that aim to take into account the steep flux gradients in the region of the upper atmosphere. An overview of these coordinates is presented. The effectiveness of each system is assessed by mapping the proton flux distribution of NASA’s AP‐8 model. Special attention is given to Hassitt’s weighted average of the atmospheric density over the drift shells of trapped particles, which appears very efficient in mapping fluxes for low L values.

At high energy, cosmic rays can only be studied by measuring the extensive air showers they produce in the atmosphere of the Earth. Although the main features of air showers can be understood within a simple model of successive interactions, detailed simulations and a realistic description of particle production are needed to calculate observables relevant to air shower experiments. Currently hadronic interaction models are the main source of uncertainty of such simulations. We will study how accelerator data can constrain the different hadronic models available for extensive air shower simulations. 1 Cosmic rays and hadronic interactions Due to the steeply falling energy spectrum of cosmic rays, direct detection by satelliteor balloon-borne instruments is only possible up to about ∼ 10 eV. Fortunately, at such high energy, the cascades of secondary particles produced by cosmic rays reach the ground and can be detected in coincidence experiments. The cascades are called extensive air showers (EAS) and are routinely used to make indirect measurements of high energy cosmic rays. As a consequence of the indirect character of the measurement, detailed simulations of EAS are needed to extract information on the primary particle from shower observables. Whereas electromagnetic interactions are well understood within perturbative QED, hadronic multiparticle production cannot be calculated within QCD from first principles. Differences in modeling hadronic interactions, which cannot be resolved by current accelerator data, are the main source of uncertainty of EAS predictions [1, 2]. In this article, we will discuss the relation between hadronic multiparticle production and EAS observables and the constrains given by accelerator data.

Table of Introduction Claus Weitkamp From visual perception to LIDAR What this book does not consider How it all began LIDAR literature and information dissemination What a LIDAR is The LIDAR return signal and LIDAR equation Atmospheric parameters that can be measured Interaction processes used LIDAR systematics LIDARs considered in this book LIDAR Guidelines Femtosecond white light LIDAR Jerome Kasparian, Jean-Pierre Wolf, Ludger Woste et al Introduction The Teramobile system Non-linear propagation of TW pulses Atmospheric filamentation experiments LIDAR experiments of atmospheric traces Aerosols Conclusion Elastic LIDAR measurement of the troposphere Nobuo Tekeuchi Outline of troposphere by LIDAR monitoring LIDAR equation and analytical solution LIDAR system and example of monitoring Monitoring of aerosol optical properties LIDAR network monitoring Conclusion and future trend Trace gas species detection in the lower atmosphere by LIDAR Bertrand Calpini and Valentin Simeonov Introduction Differential absorption LIDAR equation The detection of trace gas species by DIAL DIAL measurements in the UV (200 to 450 nm) DIAL measurements in the near-IR (1 to 4 m) DIAL measurements in the mid-IR (5 to 11 m) Tropospheric ozone as a special case study Comparison between LIDAR measurements and model predictions Perspectives Resonance fluorescence LIDAR for measurements of the middle and upper atmosphere Xinzhao Chu and George C. Papen Introduction Advanced technology of resonance fluorescence LIDAR Key results of LIDAR measurements in the middle and upper Atmosphere Conclusions and future outlook Fluorescence spectroscopy and imaging of LIDAR targets Sune Svanberg Abstract Introduction Fluorescence Remote fluorescence recording Illustrations of fluorescence LIDAR applications Discussion Wind LIDAR Sammy W. Henderson, Phillip Gatt, David Rees, and Milton Huffaker Introduction Background Doppler wind LIDAR principle of operation Doppler wind LIDAR theory of operation System Architectures and example systems Wind measurement applications Summary and future prospects Airborne LIDAR systems Edward V. Browell, William B. Grant, and Syed Ismail Introduction Specific requirements for airborne LIDAR Specific airborne LIDAR application areas Differential absorption LIDAR Resonance fluorescence LIDAR Raman LIDAR Atmospheric temperature, density Hydrospheric LIDAR Laser altimeters Future developments expected Summary and conclusion Space-Based LIDAR Upendra N. Singh, Syed Ismail, Michael J. Kavaya, David M. Winker, and Farzin Amzajerdian Introduction Technology development for space-based LIDAR missions Space-based LIDAR for observation of aerosols and clouds LIDAR altimetry Wind measurement from space Differential absorption LIDAR

Spatial and temporal changes that transmitted radio signals may go through are attributed to variations in the atmospheric conditions as well as other environmental factors. This work evaluates and establishes some atmospheric and environmental variables that have a dominating impact on temporal signal strength fluctuations that are experienced even on a fixed location. The average refractivity gradient dN/dh computed from hourly measurement taken at a fixed location for seven days was -61.3 N/km and so the average propagation conditions correspond to the normal mode, although super refraction was to be expected at about 10 am and 8 pm. On the overall, the variation in dN/dh does not actually explain the temporal variations in the received signal Pr, since the correlation between the variables is as low as 0.091. Among the environmental factors investigated for their effect on signal strength fluctuations, receiver location has a dominating impact. Virtually all weather phenomena take place in the troposphere which is the portion of the Earth's atmosphere that extends from the surface of the Earth to a height of about 6 km at the Poles and 18 km at the equator. The temperature in this region decreases rapidly with altitude, clouds form, and there may be much turbulence because of variations in temperature, density, and pressure. These fluctuations in the atmospheric parameters like temperature, pressure and humidity in the troposphere are said to cause the refractive index of the air in this layer to vary from one point to another (14). This study evaluates the correlation between instantaneous or temporal signal strength fluctuation and the associated refractivity gradient based on hourly data of the atmospheric parameters obtained from Nigerian Meteorological Centre, Bauchi station and the simultaneous hourly GSM Signal Strength measured at a fixed location.

Layers characterize our planet. From its inner core to the top of the atmosphere and beyond, we usually depict its structure and our knowledge on it, dividing it into parts. From bottom to top, the...

The earth’s atmosphere is ‘largely’ opaque to infrared radiation and observations at these wavelengths are only possible if carried out from above the atmosphere.

Abc = element of matrix Ad to which aDcrit is the most sensitive Ad = stable linear reference state-space matrix As = Schweighart and Sedwick model state-space matrix aDcrit = magnitude of the differential drag acceleration ensuring stability aDrel = magnitude of the differential aerodynamic drag acceleration aPrelx, aPrely = differential accelerations caused by orbital perturbations excluding drag, along x and y directions of the local vertical/local horizontal frame CDC, CDT = chaser and target spacecraft’s drag coefficients e = tracking error vector it = target’s initial orbit inclination J2 = second-order harmonic of Earth gravitational potential field (Earth flattening) lb, ub = lower and upper bounds for the optimization mC, mT = chaser and target spacecraft’s mass Re = Earth mean radius Rt = position vector of the target in relation to the Earth SC, ST = chaser and target spacecraft’s crosswind surface area u = on/off control signal V = Lyapunov function vs = spacecraft velocity vector magnitude with respect to the Earth’s atmosphere xn = state-space vector of the nonlinear system including relative position and velocity between the spacecraft in the local vertical/local horizontal orbital frame xt = reference state-space vector in the local vertical/ local horizontal orbital frame δAop = modifications made to matrix Ad for the optimized adaptation μ = Earth’s gravitational parameter ρ = atmospheric density ω = magnitude of the orbital angular velocity of the target

To create realistic images using computer graphics, an important element to consider is atmospheric scattering, that is, the phenomenon by which light is scattered by small particles in the air. This effect is the cause of the light beams produced by spotlights, shafts of light, foggy scenes, the bluish appearance of the earth's atmosphere, and so on. This paper proposes a fast method for rendering the atmospheric scattering effects based on actual physical phenomena. In the proposed method, look-up tables are prepared to store the intensities of the scattered light, and these are then used as textures. Realistic images are then created at interactive rates by making use of graphics hardware.

In Twenty first century, world is facing two major problems global warming and terrorism. Global warming means expected continuous increase in average temperature air, Ocean and surface of earth from twentieth century. In 2005 average increase of temperature for 100 years near earth crust is found to be 180 centigrade. Green House Effect is natural and critical process. Surrounding near earth act as surface of Green House. 31 percent of rays emerging from Sun reflect back to universe from surface of earth and 20 percent is absorb by the atmosphere. Remaining rays is absorb by the waves present at earth surface and also by the waves present at sea surface and then converted into energy. This energy makes the atmospheric hot. Some gases of earth atmosphere act as a surface of green house and bind the energy at surface of earth by making earth surface hot and due to this possibility of life is possible on earth. Analytical study of Greenhouse effect is made in the present article.

Avoiding the Doldrums: Evaluating the Need for Change in the Offshore Wind Permitting Process

Ozone is one of the constituent gases of the atmosphere. This gas is concentrated in the stratosphere layer functions as a UV filter so as not to cause damage on the surface of the earth. This layer of ozone in most produced by the reaction of oxygen with ultraviolet light. Ozone in the troposphere is the layer of air pollutants and harmful to the respiratory system of human, animal and plant metabolism. The presence of ozone in Earth's atmosphere in low concentrations throughout the year. Decreased concentration or the ozone layer depletion triggered by the compounds of CFCs (Chloro Fluoro Carbon) and ODS (Ozone depleting Subsantance). ODS compounds include nitrogen oxide (N2O) is a byproduct of combustion, methyl bromide, carbon tetrachlorida and methyl chloroform. To determine the thickness of the ozone layer is measured by satellite instruments or Nimbus-7 satellite instruments EP-toms. Total concentration of atmospheric ozone standard can be determined using the unit DU (Dobson Unit). Concentration at a point can also be measured in units of ppb (parts per billion) or in μg.m³. Efforts to reduce ozone layer depletion, among others, regularly measure the thickness of the ozone, suppress the use of CFC compounds that are widely used as refrigrant in freezers, refrigerators, room air conditioning and engine cooling, spray cans for air freshener, perfumes, solvents, foam developers and reduce the use of ODS substances which have been agreed by the international community through the Montreal Protocol, Canada in 1987

La destruction, à partir du début des années 1980, de la couche d'ozone stratosphérique, par des constituants halogénés issus de l'industrie chimique, est considérée aujourd'hui comme la première atteinte des activités humaines à l'environnement atmosphérique global. En parallèle, le protocole de Montréal, signé en 1987 pour réguler l'émission des substances destructrices d'ozone, fait figure de pionnier dans le domaine de la réglementation mondiale destinée à protéger l'environnement terrestre. Il a notamment inspiré le protocole de Kyoto signé en 1992 pour réguler les émissions des gaz à effet de serre. Plus de deux décennies après la signature du protocole de Montréal, le présent article fait le point sur la réduction des émissions de gaz destructeurs d'ozone, sur l'état de la couche d'ozone et sur les prévisions quant à son rétablissement, compte tenu du changement climatique et de son influence sur le retour à l'équilibre de l'ozone. Le bénéfice additionnel du protocole de Montréal quant aux émissions de gaz à effet de serre est également évoqué.