LIDAR monitoring of the temperature in the middle and lower atmosphere

Two methods are described to monitor the temperature of the atmosphere from the ground to 100 km altitude. The Rayleigh LIDAR is now widely used (the French network includes four of those characteristics of which are given), and here, the major results obtained from this technique are presented. The second method, which completes the Rayleigh LIDAR downwards, uses the rotational Raman lines of O₂ and N₂. The method is briefly described and first results are presented. Including both the Rayleigh and Raman modes leads to a continuous temperature measuring method to survey changes in the lower and middle atmosphere.     

LIDAR systems operating in a non-Kolmogorov turbulent atmosphere

ABSTRACT

It is well known that in free atmosphere the Kolmogorov power spectrum of the refractive index might not properly describe the actual turbulence behavior. In this paper, we use general non-Kolmogorov power spectrum for theoretical investigation of laser beam propagation in the double-passage problem: transmitter–target–receiver. The major application of our work is the Light Detection And Ranging (LIDAR) system operating at high altitudes, where non-Kolmogorov turbulence may be present. On confining ourselves to the weak turbulence regime, we show that the long-term average beam intensity profile, the long-term beam spread and the scintillation index are substantially affected by the non-Kolmogorov turbulent channels. Our analysis is valid for both bi-static and mono-static configurations, the latter leading to the enhanced backscattering effects.     

Stochastic electromagnetic beams for LIDAR systems operating through turbulent atmosphere

With the help of the generalized Huygens–Fresnel integral and the ABCD matrix approach a bistatic LIDAR system involving a rough target at a distant location in a turbulent atmosphere is modeled. The system operates by means of an optical beam which has arbitrary spectral composition, and states of coherence and polarization. The rough target is modeled as a combination of a Gaussian mirror and a thin phase screen which induces phase perturbations of the components of the electric field. The analytical form of the cross-spectral density matrix of the returned beam is determined, from which the effect of the rough target on the spectral density (intensity) and polarization of the returned wave is analyzed. E. Watson’s work performed while assigned to the Ladar and Optical Communications Institute, University of Dayton, Dayton, OH 45469, USA.     

A numerical method for calculating the mean intensity in an inhomogeneous rayleigh scattering atmosphere

We describe a method for calculating directly the mean integrated intensity in an inhomogeneous Rayleigh scattering atmosphere using a combined variational and iterative technique. This method is particularly useful for computing dissociation rates in aeronomical problems. Simple semi-analytic expressions are derived.     

A novel polarization interferometer for measuring upper atmospheric winds

A static polarization interferometer for measuring upper atmospheric winds is presented, based on two Savart plates with their optical axes perpendicular to each other. The principle and characteristics of the interferometer are described. The interferometer with a wide field of view can offer a stable benchmark optical path difference over a specified spectral region of 0.55--0.63~\mu m because there are no quarter wave plates. Since the instrument employs a straight line common-path configuration but without moving parts and slits, it is very compact, simple, inherently robust and has high throughput. The paper is limited to a theoretical analysis.     

Tidal activity in the middle atmosphere

Summary Recent progress in the study of tides in the middle atmosphere ((10÷120) km) includes: i) development of more realistic thermal excitation and numerical simulation models; ii) observational efforts which delineate average seasonal, latitudinal and vertical structures of tides and shorter term variations of these. A survey is presented here of the variation with time and height of atmospheric tides observed at Budrio (45° N, 12° E) in the wind field between 75 and 115 km of altitude during the period 1978–82. Thermal excitation of the tides is mainly due to absorption of solar incident flux by ozone in the stratosphere and water vapour in the troposphere, release of latent heat in clouds, and heat conduction at the ground. The spectral analysis of wind data, obtained at Budrio in a few days of each month of 1978, shows that the semi-diurnal tide is the most easily observable by its regularity and amplitude: consistent amplitudes (around 20 m/s) are recorded in Summer and Winter months at 95 km. The vertical profiles of amplitudes of the diurnal, semi-diurnal and terdiurnal tide observed in zonal winds in some periods of 1979 (January 11–26, March 14–28, July 26–August 4, and September 11–23) demonstrate the great variability of tides not only over a large time scale (seasonal variations) but also on a reduced scale (variations in a few days).

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Riassunto I recenti progressi nello studio delle maree nell'atmosfera media ((10÷120) km), includono i) lo sviluppo di modelli piú realistici di eccitazione termica e modelli di simulazione numerica, ii) osservazioni che delineano strutture medie stagionali, latitudini e verticali di maree nonché le loro variazioni a piú breve periodo. Si presenta qui una rassegna delle variazioni nel tempo e con l'altezza delle maree atmosferiche osservate a Budrio (45° N, 12° E) nel campo dei venti tra 75 e 115 km di quota durante il periodo 1978–1982. La sorgente di eccitazione termica di queste oscillazioni è principalmente l'assorbimento del fluosso di energia solare incidente da parte dell'ozono nella stratosfera e del vapor d'acqua nella troposfera, il rilascio di calore latente nelle nubi, e la conduzione di calore al suolo. L'analisi spettrale dei dati di vento, osservato a Budrio nel corso di alcuni giorni di ogni mese dell'anno 1978, mostra che la marea semidiurna è la componente piú facilmente osservabile per la sua regolarità ed ampiezza: ampiezze consistenti (circa 20 m/s) sono registrate nei mesi estivi ed invernali a 95 km. I profili verticali delle ampiezze delle maree diurna, semidiurna e terdiurna osservate nel campo dei venti zonali in alcuni periodi del 1979 (11–25 gennaio, 14–28 marzo, 26 luglio–4 agosto e 11–23 settembre) mettono in evidenza la grande variabilità delle maree non solo su ampia scala temporale (variazioni stagionali), ma anche su scala ridotta (variazioni nell'arco di alcuni giorni).

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Резюме Недавний прогресс в исследовании приливов в средней атмосфере ((10÷120) км) включает: 1) развитиye более реалистического теплового возбуждения и численных моделей для моделирования; 2) результаты наблюдений, которые описывают усредненные сезонные, щиротные и вертикальные структуры приливов и более краткосрочные изменения этих структур. В работе предлагается обзор изменений во времени и по высоте атмосферных приливов, наблюденные в Будрио (45° N, 12° E) в поле ветров в интервале от 75 до 115 км, в течение 1978–82 г.г. Тепловое возбуждение приливов, в основном, обусловлено поглощением потока солнечной радиации озоном в стратосфере и водяным паром в тропосфере, высвобождением скрытой теплоты в облаках и теплопроводностью на Земле. Спектральный анализ данных для ветра, полученных в Будрио в течение нескольких дней каждого месяца 1978 г., показывает, что полусуточный прилив наиболее легко наблюдается ив-за регулярности и амплитуды: соответствуюшие амплитуды (около 20 м/с) регистрируются в летние и зимние месяцы на высоте 95 км. Вертикальные профили амплитуд суточных, полусуточных и восьмичасовых приливов, наблюденные в зональных ветрах в некоторые периоды 1979 г. (11–26 января, 14–28 марта, 26 июля–4 августа, 11–23 сентября) обнаруживают значительную изменчивость не только на протяжении больщого промежутка времени (сезонные изменения), но с меньщим временным масщтабом (изменения в течение нескольких дней).

     

Investigation of the distribution of particles in atmosphere by means of a LIDAR working at two frequencies

The paper deals with measurement of the atmosphere by means of the LIDAR working at two wavelengths (530 nm and 266 nm) in the Kiev suburban region in May 1985. From the results acquired we have determined the state of the Junge's distribution functions of atmospheric aerosols.     

Ground-based Doppler radio-frequency refractometry of the atmosphere

An exact relationship between the Doppler shift of a satellite signal and astronomical refraction is used to reduce the problem of reconstruction of the altitude profile of the refractive index to an inverse refraction problem. The range of observation angles in which measurements are informative is determined. Mathematical modeling is used to obtain statistical estimates of the possible reconstruction accuracy for various sets of climatic conditions, and the required accuracy for measurement of Doppler frequency and satellite orbit parameters is determined.Scientific-Research Radio-Physics Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, Nos. 3, 4, pp. 211–219, March–April, 1992.     

Calculation of the parameters of a spectrophotometric system for measuring airglow brightness in the upper atmosphere from space

We present energy calculations for the basic parameters of a spectrophotometric system designed for recording the vertical distributions of the spectral brightness of hydroxyl airglow and the brightness of airglow from the green line of atomic oxygen in the upper layer of the Earth's atmosphere. We consider the scheme for conducting the “Hydroxyl” space experiment with instrumentation in the spectrophotometric system and methods for measuring the brightnesses of the indicated airglow components in sessions for observation of the Earth's night upper atmosphere in the altitude range 80–110 km from on board the International Space Station (ISS). __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 125–133, January–February, 2008.     

激光雷达测量大气温度的傅里叶分析方法

 在对流层(小于12km），由于大气中气溶胶的存在，传统的利用大气中瑞利散射光谱测量大气温度的方法具有一定的局限性。借助傅里叶分析方法对不同高度的大气后向散射光谱通过碘吸收池所产生的不同透过率曲线进行处理，同时考虑了对流层中气溶胶的影响，可得到对流层中不同高度、不同大气后向散射比条件下的温度轮廓线。     

激光雷达测量大气温度的傅里叶分析方法

在对流层(小于12km）,由于大气中气溶胶的存在,传统的利用大气中瑞利散射光谱测量大气温度的方法具有一定的局限性。借助傅里叶分析方法对不同高度的大气后向散射光谱通过碘吸收池所产生的不同透过率曲线进行处理,同时考虑了对流层中气溶胶的影响,可得到对流层中不同高度、不同大气后向散射比条件下的温度轮廓线。     

The development of an optical Doppler technique for measuring flow velocities

For a generalized scheme of LDV, the expressions describing the light intensity distribution in a photo-receiver plane with regard to the size of the scattering particles have been calculated using Fourier optics.The LDV signal should be considered as a narrow-band stochastic process representing the sum of random phase radio frequency pulses arising from each light scattering particle. Then the expected error of the mean velocity measurement is equal to half the reciprocal of the number of interference fringes squared and the input signal-to-noise ratio is equal to the square root of the product of Doppler frequency, fringe number and averaging time.The device developed by the authors includes d.c. optical signal compensation. The device is described and the results of its use are given.     

A measuring system for reflection coefficient investigations of materials heated by CO2-laser radiation in a controllable atmosphere

An experimental system is described which is intended for measurements of reflection coefficients at wavelengths of 0.63; 1.15; 3.39, and 10.6 μm and of the thermodynamic temperature of the surface of materials heated in air or in an inert atmosphere at pressures from 1.3·10² to 1.3·10⁵ Pa. An analysis of the errors in reflection coefficient and temperature measurements is made. B. I. Stepanov Institute of the Physics of the National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 608–611, July–August, 1998.