A Theory of Radio Scattering in the Troposphere

Booker, Henry G.; Gordon, William E.

doi:10.1109/jrproc.1950.231435

Cited by 382 publications

(86 citation statements)

References 9 publications

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“…12) and (3. 13) are the required and correct fields, which coincide with Booker-Gordon's (1950) expressions obtained from rather physical consideration.…”

Section: The Volume Integral Termmentioning

confidence: 55%

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Integration of MAXWELL's Equations in Microwave Propagation beyond the Horizon

Naito¹

1963

Pap.Met.Geophy

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A direct integration of MAXWELL'S equations is performed in the case of microwave propagation beyond the horizon, taking into consideration the atmospheric turbulence.Following the method developed by STRATTON-CHU, the solution is found to be composed of a volume integral term and a surface integral one with the help of BoRN's approximation.The former term coincides with the expression so far given by solving a wave equation for the electric or magnetic vector.However, this does not give a transverse wave at great distances from the so-called scattering region, and, hence, this does not satisfy MAXWELL'S equations. In other words, a solution of a wave equation of the second order is not always a solution of MAXWELL'S equation of the first order.In order to avoid the above difficulty, a new method is proposed to correct the volume integral term, giving the fundamental expression for the turbulent scattering.Concerning the suface integral term, there is some correction needed in case of BoRN's approximation and the term corrected is found to agree with J. ORTIISCS theoretical result in which the earth is regarded rather as a black body.In case elevated layers with discontinuity are present in the atmosphere, STRATTON-CITU'S formalization is also shown to be applicable, giving usual layer-reflection.Consequently, without enough information on atmospheric structures, the field beyond the horizon is composed of three parts : scattering due to eddies, diffraction due to the earth of a black body type and layerreflection, which are of equal weight from a theoretical point of view at present.

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“…12) and (3. 13) are the required and correct fields, which coincide with Booker-Gordon's (1950) expressions obtained from rather physical consideration.…”

Section: The Volume Integral Termmentioning

confidence: 55%

“…The second term Coincides with H. G. BOOKER and W. E. GORDON'S (1950) expression obtained rather intuitively from a physical consideration. STARAS and WHEELON (1959) used a wave equation not for Hertz vector, but for the electric vector, similar to (1.…”

Section: It Follows From (1 2) Thatmentioning

confidence: 82%

Integration of MAXWELL's Equations in Microwave Propagation beyond the Horizon

Naito¹

1963

Pap.Met.Geophy

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“…A VHF ST radar offers the possibility of performing experimental studies on atmospheric turbulence, for example, theoretically investigated by Booker and Gordon (1950), Ottersten (1969), or Tatarski (1971. In a stratified fluid, turbulent events are classically interpreted as the result of flow instabilities (e.g.…”

Section: Errors In Isotropic Turbulence Parameter Measurementsmentioning

confidence: 99%

Temperature sheets and aspect sensitive radar echoes

Luce

Crochet

Dalaudier³

2001

Ann. Geophys.

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Abstract. There have been years of discussion and controversy about the existence of very thin and stable temperature sheets and their relationship to the VHF radar aspect sensitivity. It is only recently that very high-resolution insitu temperature observations have brought credence to the reality and ubiquity of these structures in the free atmosphere and to their contribution to radar echo enhancements along the vertical. Indeed, measurements with very highresolution sensors are still extremely rare and rather difficult to obtain outside of the planetary boundary layer. They have only been carried out up to the lower stratosphere by Service d'Aéronomie (CNRS, France) for about 10 years. The controversy also persisted due to the volume resolution of the (Mesosphere)-Stratosphere-Troposphere VHF radars which is coarse with respect to sheet thickness, although widely sufficient for meteorological or meso-scale investigations. The contribution within the range gate of many of these structures, which are advected by the wind, and decay and grow at different instants and could be distorted either by internal gravity waves or turbulence fields, could lead to radar echoes with statistical properties similar to those produced by anisotropic turbulence. Some questions thus remain regarding the manner in which temperature sheets contribute to VHF radar echoes. In particular, the zenithal and azimuthal angular dependence of the echo power may not only be produced by diffuse reflection on stable distorted or corrugated sheets, but also by extra contributions from anisotropic turbulence occurring in the stratified atmosphere. Thus, for several years, efforts have been put forth to improve the radar height resolution in order to better describe thin structures. Frequency interferometric techniques are widely used and have been recently further developed with the implementation of high-resolution data processings. We begin by reviewing briefly some characteristics of the ST radar echoes with a particular emphasis on recent works. Their possible coupling with stable sheets is then presented and their known characteristics are described with some hypotheses concernCorrespondence to: H. Luce (luce@kurasc.kyoto-u.ac.jp) ing their generation mechanisms. Finally, measurement campaigns that took recently place or will be carried out in the near future for improving our knowledge of these small-scale structures are presented briefly.

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“…Radio waves are scattered in the lower atmosphere by variations in pressure, temperature, and humidity that produce variations in the refractive index [e.g., Booker and Gordon, 1950;Bean and Dutton, 1966; Balsley and Balsley, 1981]. It has been observed that at MF/HF/VHF frequencies, this radar backscatter is aspect sensitive; in other words, the ratio of the backscatter power in the vertical direction versus that in an off vertical direction is greater than Copyright 2001 by the American Geophysical Union.…”

Section: Introductionmentioning

confidence: 99%

Wavelet analysis of high&hyphen;resolution temperature data with applications to radio wave scattering

Chen¹,

Kelley²,

Walters³

2001

Radio Science

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Abstract. High-resolution balloon-borne temperature measurements have been made in the troposphere and stratosphere during late fall over the western plains of the United States. In one such experiment the data are of remarkable quality and quite suitable for investigating methods of separating organized and turbulent features from a geophysical data stream, exploring atmospheric dynamics, and estimating VHF radar backscatter. We are particularly interested in the mechanisms creating aspect sensitivity, i.e., a nonunity ratio of vertical to well off-vertical radar backscatter. We find that very steep positive vertical temperature gradients, as high as 40.0 K/km, can be supported. On the other hand, negative gradients are limited to values near the marginal stability boundary. The structures are thus anisotropic and similar to ramp cliff features found in other fluids. We use wavelet analysis to isolate the organized components of the signal and, after subtraction, the residual signal is investigated to determine its character. The Fourier transform of the residual is Kolmogorov in nature, unlike that of the original data stream, and yields Cn 2, the refractive index structure parameter, in good agreement with the higher-order structure function approach; this supports the success of our partition. We calculate the Fresnel reflection coefficient using the wavelet coefficients; the turbulent scatter is found using Cn 2. The ratio between the Fresnel scatter and the turbulent scatter, i.e., the aspect sensitivity, is -! 0 decibels in the troposphere and over 20 decibels in the stratosphere, in agreement with published observations and supporting our assumption that the organized features have horizontal extent exceeding the Fresnel scale. IntroductionRadio waves are scattered in the lower atmosphere by variations in pressure, temperature, and humidity that produce variations in the refractive index [e.g.,

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A Theory of Radio Scattering in the Troposphere

Cited by 382 publications

References 9 publications

Integration of MAXWELL's Equations in Microwave Propagation beyond the Horizon

Integration of MAXWELL's Equations in Microwave Propagation beyond the Horizon

Temperature sheets and aspect sensitive radar echoes

Wavelet analysis of high&hyphen;resolution temperature data with applications to radio wave scattering

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