Дисертації з теми "VLF atmosphere"
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Groves, Keith Michael. "Nonlinear ionospheric propagation effects on UHF and VLF radio signals." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/52949.
Повний текст джерелаIncludes bibliographical references (p. 179-184).
by Keith Michael Groves.
Ph.D.
Low, David J. "Studies of the lower atmosphere with a VHF wind profiler /." Title page, abstract and contents only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phl9121.pdf.
Повний текст джерелаCulbertson, Gary W. "Assessments of atmospheric affects of VHF and UHF communications." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA226661.
Повний текст джерелаThesis Advisor(s): Davidson, Kenneth L. Second Reader: Tulloch, A. W. "March 1990." Description based on signature page as viewed on August 26, 2009. DTIC Descriptor(s): Atmospheric Refraction, Very High Frequency, Ultrahigh Frequency, Communication And Radio Systems, Tools, Parameters, Wind, Forecasting, Accuracy, Theses, Electromagnetic Radiation, Pressure, Radiosondes, Refraction, Pacific Ocean, Climatology, Troposphere, Humidity, Gradients, Shores, East(Direction), Computer Printouts, Television Display Systems, Weather, Guided Missiles, Synoptic Meteorology, Test And Evaluation, Data Bases. DTIC Identifier(s): IREPS (Integrated Refractive Effect Prediction System). Author(s) subject terms: Communications, IREPS, refraction. Includes bibliographical references (p. 70-71). Also available online.
Campos, Ortega Edwin F. 1972. "Analyses of precipitation signal using VHF vertically-pointing radar." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102965.
Повний текст джерелаThis research develops a multi-faceted approach for the calibration of VHF vertically-pointing radars, by combining a first calibration method that compares the recorded VHF signal to power coming from a noise generator and a second calibration method that compares recorded VHF signal to cosmic radiation. This approach allows the retrieval of antenna and receiver parameters (such as noise levels, efficiency, and gain), and four other equations for the corresponding errors. In addition, we develop an equation for calibrating Doppler spectra.
The analysis is focused on rain observations with VHF radar. We verify the hypothesis that |K|2 = 0.93 for most of the rain observations at VHF band. A signal-processing algorithm for extracting the rain signal out of the VHF power spectra is then presented. This work also derives a general version of the radar equation valid for vertically pointing radars, as well as a particular version of this equation valid for the McGill VHF radar. The study then makes numerical simulations of several profiles of precipitation signal at VHF band, by combining high-resolution profiles of precipitation signal (from a calibrated X-band radar) and the VHF antenna pattern in our general version of the radar equation. The analyses indicate that VHF reflectivity at gates above the melting layer is artificially enhanced by the precipitation signal collected from the side lobes.
This work also studies the effect of precipitation in the scattering properties of clear air. We analyze several cases of stratiform and convective rain, occurring in a continental mid-latitude environment (Montreal, Lat.45.41°N, Long.73.94°W). For these cases, Doppler spectra taken by a VHF vertically-pointing radar were used to retrieve simultaneous co-located values of precipitation intensity (rainrates) and degrees of refractive index fluctuation (structure-function parameter for refractivity turbulence, Cn2). We validated these retrievals using co-located, calibrated measurements of precipitation signal at X-band. The comparison between equivalent reflectivity factors at X and VHF bands agrees within 1 dB. The study includes rainrates between 0.3 and 78 mm/h, and Cn2 values between 10-16 and 10-12 m-2/3 , retrieved from the VHF spectra at 2.5 km height. The study finds that the occurrence of rain is associated with distinctive changes in the structure of air refractive index fluctuations, and that these changes are of a turbulent nature for the most intense rainrates.
Beldon, Charlotte. "VHF radar studies of mesosphere and thermosphere." Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512294.
Повний текст джерелаMu, K. L. "Investigation of tropospheric turbulence using the Adelaide VHF radar /." Title page, abstract and contents only, 1991. http://web4.library.adelaide.edu.au/theses/09SM/09smm941.pdf.
Повний текст джерелаBaudino, Jean-Loup. "Analyse des données photométriques et spectroscopiques infrarouges d'exoplanètes obtenues avec l'instrument SPHERE au VLT." Observatoire de Paris, 2015. https://hal.science/tel-02095304.
Повний текст джерелаSince 2003 direct imaging of exoplanets allows us to obtain spectroscopic and photometric data to characterize their atmospheres. First, our goal was to develop a simple tool to interpret data from SPHERE and GPI to derive planetary physical parameters. We developed a model of young giant exoplanet (called Exo-REM for Exoplanet Radiative-convective Equilibrium Model). Input parameters are surface gravity g, effective temperature (Teff) and an elemental composition. Opacity sources include the H2 –He collision-induced absorption and atomic and molecular lines from eight compounds (including CH4 updated with the Exomol linelist). We consider clouds of iron and silicates without scattering. I have used Exo-REM to analyse photometric and spectral observations of HD 95086 b, beta Pictoris b, kappa Andromedae B, HR 8799 b, c, d, e, GJ 758 B. I finally investigated the presicion to which the above parameters can be constrained from SPHERE measurement
Mauriet, Sylvain. "Simulation d'un écoulement de jet de rive par une méthode VOF." Phd thesis, Université de Pau et des Pays de l'Adour, 2009. http://tel.archives-ouvertes.fr/tel-00463578.
Повний текст джерелаLee, Christopher Francis. "Use of wind profilers to quantify atmospheric turbulence." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/use-of-wind-profilers-to-quantify-atmospheric-turbulence(d6a12ed2-533a-4dae-9f0d-747bc0b4c725).html.
Повний текст джерелаDrevard, Déborah. "Etude expérimentale et numérique de la propagation d'ondes de gravité en zone de déferlement." Phd thesis, Université du Sud Toulon Var, 2006. http://tel.archives-ouvertes.fr/tel-00141744.
Повний текст джерелаL'objectif de ce travail est d'étudier expérimentalement et numériquement la propagation et le déferlement
d'ondes de gravité.
La première partie, expérimentale, propose des méthodes de calcul, basées sur les houles de Stokes, pour la mesure d'ondes partiellement stationnaires à partir d'instruments de type électromagnétique (S4) ou
acoustique (ADV) donnant des mesures synchrones de vitesses et/ou de pression. Les influences du courant,
de la direction de propagation, de la profondeur d'immersion des appareils ainsi que des effets non
linéaires sont alors étudiés à partir de données en bassin et in situ.
La deuxième partie, numérique, consiste en la validation d'une méthode de suivi de surface libre de type
SL-VOF (Semi-Lagrangian Volume Of Fluid), insérée dans un code de calcul industriel (code EOLE de la
société Principia R&D). L'onde de gravité est modélisée par un soliton. L'étude de la propagation et du
déferlement du soliton est effectuée pour deux applications : sur une marche (discontinuité du fond) puis sur un fond de pente constante 1/15. L'évolution de la surface libre, son élévation et le champ de vitesses
sont alors comparés aux résultats expérimentaux.
Fillol, Jean-Michel. "Restitution des profils de reflectivite et de vitesse dans la basse atmosphere a l'aide de methodes inverses : application au cas d'un mini-radar air clair vhf." Toulon, 1994. http://www.theses.fr/1994TOUL0013.
Повний текст джерелаMerien, Davy. "Variabilité biooptique à différentes échelles spatiales et temporelles dans l'Atlantique nord-est : interprétations biogéochimiques." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2003. http://tel.archives-ouvertes.fr/tel-00004148.
Повний текст джерелаLow, David J. (David John) 1969. "Studies of the lower atmosphere with a VHF wind profiler / by David J. Low." 1996. http://hdl.handle.net/2440/18720.
Повний текст джерелаxxiv, 267 p., [1] leaf of plates : ill. ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1996
Low, David J. (David John) 1969. "Studies of the lower atmosphere with a VHF wind profiler / by David J. Low." Thesis, 1996. http://hdl.handle.net/2440/18720.
Повний текст джерелаLin, Tszer-Horng, and 林澤宏. "The Study of Interactions between Background Atmosphere and Hydrometers by Using Chung-Li VHF Radar." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/13063234918842730738.
Повний текст джерела國立中央大學
太空科學研究所
84
Using the datasets of frontal precipitation passed on Dec. 12 1995 by Chung-Li VHF radar, proceed the correlation analysis of atmospheric and prcipitation parameters. We can distinguish two distinct precipitation events from the observational time according to the variation of precipitation echo varied with height and time, and recognize the bright band by the data of airsonde in time and the vertical motion of backound atmosphere. Correlation analysis applied on series of precipitation echo varied with height can present the delay phenomena of raindrop''s falling process, which can be regarded as a symbol of tracking raindrops. Perfect correlations exist between raindrops'' falling velocities and precipitation echo, which can be described as a exponential form V=a*P^b. There is a obvious turning at the melting layer respond to the height variation of coefficient "b". Additionally , it is weak that the vertical motion of background atmosphere reacted on the hydrometers for the datasets obtained from 1995''s observations. The study of interactions between precipitation particles and background atmosphere is concerned about that whether the hydro- meter will be frozen-in the background atmosphere or not. At the time, we define the checking parameters "df" and "rf" to be the quantized index of frozen-in level. In addition, the parameter settings with transmitting and receiving in time for vertical and off-vertical beams was applied on the observation of frontal precipitation on Apr. 13. 1996. In such way, we do not have to consider if the time resolution as the setting of 1995 could describe the variation of the targets. After these experiments, that hydrometers were not frozen-in background atmosphere is approved,and the correlations such as checking parameters versus falling velocities and radial wind velocities are also not quite obvious. Finally, the effect of anti-frozen-in for ice crystals are more severe than raindrops.
McIntosh, Daniel L. "Comparisons of VHF meteor radar observations in the middle atmosphere with multiple independent remote sensing techniques." 2010. http://hdl.handle.net/2440/60068.
Повний текст джерелаhttp://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474902
Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2010
McIntosh, Daniel L. "Comparisons of VHF meteor radar observations in the middle atmosphere with multiple independent remote sensing techniques." Thesis, 2010. http://hdl.handle.net/2440/60068.
Повний текст джерелаThesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2010
Mu, K. L. (Kong Lem). "Investigation of tropospheric turbulence using the Adelaide VHF radar." Thesis, 1991. http://hdl.handle.net/2440/110379.
Повний текст джерелаPai, Chien-hung, and 白劍鴻. "Using Chung-Li VHF radar to Study atmospheric gravity waves exciting by precipitation." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/23485645159426730787.
Повний текст джерела國立中央大學
太空科學研究所
95
One of the most important topics in researching atmospheric gravity waves is to discussing the energy source of the waves and the mechanicism of excitation。 Owing better resolution of time-space and the capability to detect the echoes from precipitation and clear air, the VHF radars became good researching tool for study atmospheric waves in precipitating environment. This research using Chung-Li VHF radar as a researching tool has found that when Tai-kei typhoon moving northward, she has tilted up a 15°-27° angle from the surface of the earth, and she disturbed the change of wind direction. It is also found that the depletion of the air echoes, because the increasing of turbulence mixing effect. Finally,it is found that the precipitation particles do excite gravity waves propagating upward.
PAN, ZHEN-JIE, and 潘貞杰. "Investigation of atmospheric dynamics by VHF radar models of observational techniques and applications." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/72913422793408419970.
Повний текст джерелаHan, Feng. "Midlatitude D Region Variations Measured from Broadband Radio Atmospherics." Diss., 2011. http://hdl.handle.net/10161/3856.
Повний текст джерелаThe high power, broadband very low frequency (VLF, 3--30 kHz) and extremely low frequency (ELF, 3--3000 Hz) electromagnetic waves generated by lightning discharges and propagating in the Earth-ionosphere waveguide can be used to measure the average electron density profile of the lower ionosphere (
In order to understand the time scales, magnitudes and sources for the midlatitude nighttime
Based on sferic data similar to those for nighttime, we also measured the daytime
By applying the nighttime and daytime measurement techniques, we also derived the
Dissertation
Su, Ching-Lun, and 蘇清論. "Chung-Li VHF Radar observation of atmospheric echo and hydrometeors'' distribution characteristics during frontal precipitations." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/89360323217532900874.
Повний текст джерела國立中央大學
太空科學研究所
84
VHF雷達對低層大氣降水現象的觀測,經由前人的努力,對降水環境下的 大氣結構變化,已有相當程度的了解,如鋒面下的大氣和降水回波功率、 降水型態、降水粒子大小和終端速度、融解層及以上的冰晶粒子回波功率 、粒徑大小等,已做相當程度地分析研究。至於整體大氣的研究,以往皆 將低層大氣降水觀測,及較上層的對流層頂觀測分開,此處用4μs波寬觀 測,同時看到降水及對流層頂,空間解析度比以往8μs脈波寬觀測到的高 ,比較傳統探空氣球測得的對流層頂位置,VHF雷達所測得高度是較高, 對於以後欲觀測低層大氣的整體結構提供了很好的選擇。文章中將針對降 水環境下,討論大氣回波功率與大氣參數之間的關係,及大氣回波功率與 大氣結構變化的情形;發現大氣亂流回波功率和折射指數梯度平方、比濕 、比濕梯度相關性較高。由於觀測參數設定是以2μs和 4μs交互觀測, 於比較2μs和4μs降水及大氣回波功率、頻寬、垂直速度變化,發現降水 粒子分布的不均勻性及降水粒子受波束加寬效應的影響不大。 Using the VHF radar, precipitation is observed in the low atmosphere. It is understood that the structure of atmosphere varies in the precipitation environment. For example, during the front,the atmophere and precipitation echo power, the form of precipitation, the size distribution and terminal velocity of precipitation particle, the melting layer, the echo power and size of ice particle are studied suitably. However, in the past, the observation of precipitation and tropopause for studying entire atmosphere were separate. Here, the pulse width of observation is 4μs that will see both precipitation and tropopause. The height measured by the VHF radar is higher than rawinaode data. In the future, using pulse width of 4μs to make observation will provide a good opportation for studying the entire structure of low atmosphere. This dissertation will discuss the relation between the atmospheric echo power and atmospheric parameters, and the relation between the echo power and atmospheric structure. Furthermore, it will also make comparison among power, spectral width and vertical velocity of the atmosphere and precipitation echo by using the alternative observations of the pulse width of 2μs and 4μs. It is found that the distribution of precipitation particle is nonuniform in the space and that the affection of beam broading effect is small.
Kai-yin, Chen, and 陳凱胤. "Observation of Atmospheric Tides of Three Dimensional Wind Field in Mesosphere Using Chungli VHF Radar." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/06686969155947310121.
Повний текст джерела國立中央大學
太空科學研究所
104
The antenna array which consists of five Yagi antenna was used in this research.Five Yagi antenna was placed in a cross shape and the distances of each Yagi were different. The position of the target in three dimensional space can be derived by different phases.The targets may fail to locate because of different phases during operating in radar system and phase confusion. By using IGRF model, different phases during operating in radar system can be solved and geometric logic can deal with the phase confusion. Positions of the meteor tails can be located successfully and the three dimensional wind field of the mesosphere can be estimated with sliding window method.After surveying the HWM wind field observed, they are consist with my results and the Diurnal Tide features are quite obvious.