Strong scattering of radio waves by a two-layered medium with a rough boundary

1997 ◽  
Vol 40 (6) ◽  
pp. 485-492
Author(s):  
S. F. Pimenov ◽  
N. A. Stepanova
Keyword(s):  
Layered Medium ◽  
Rough Boundary ◽  
Radio Waves ◽  
Strong Scattering

scholarly journals Anisotropic radio-wave scattering from englacial water regimes, Mýrdalsjökull, Iceland

2007 ◽  
Vol 53 (182) ◽  
pp. 473-478 ◽  
Author(s):  
Kenichi Matsuoka ◽  
Throstur Thorsteinsson ◽  
Helgi Björnsson ◽  
Edwin D. Waddington
Keyword(s):  
Radio Wave ◽  
Wave Scattering ◽  
Flow Direction ◽  
Low Frequency ◽  
Radio Waves ◽  
Glacier Surface ◽  
Ice Flow ◽  
Scattering Model ◽  
Water Regimes ◽  
Strong Scattering

AbstractColinear-polarized 5 MHz radar profiling data were obtained on Mýrdalsjökull, a temperate glacier in Iceland. Radar transects, and therefore polarization planes, were aligned approximately parallel, transverse and oblique to the ice flow direction. Echoes from the shallower half to two-thirds of the ice were 10–20dB stronger on the oblique and longitudinal transects than those on the transverse transects. Anisotropy as a function of depth is clearly seen at the sites where the transects cross. Strong scattering on longitudinal transects apparently caused extinction of a radar-reflecting layer that was continuously profiled on the transverse transects. A radio-wave scattering model shows that scattering from a longitudinal water-filled conduit parallel to the glacier surface can explain the observed azimuthal variations of the echo. We conclude that low-frequency (~MHz) radio waves can help to characterize englacial water regimes.

Scattering of radio waves by a two-layer medium with a weakly reflecting rough boundary

1998 ◽  
Vol 41 (7) ◽  
pp. 600-609
Author(s):  
M. V. Kachan ◽  
S. F. Pimenov ◽  
N. A. Stepanova
Keyword(s):  
Rough Boundary ◽  
Radio Waves ◽  
Layer Medium

scholarly journals STRATIGRAPHY OF WANDA GLACIER, KING GEORGE ISLAND, ANTARCTICA, USING GROUND PENETRATING RADAR

2014 ◽  
Vol 32 (1) ◽  
pp. 21 ◽  
Author(s):  
Kátia Kellem da Rosa ◽  
Guilherme Borges Fernandez ◽  
Thais Baptista da Rocha ◽  
Felipe Lorenz Simões ◽  
Rosemary Vieira ◽  
...  
Keyword(s):  
Internal Structure ◽  
Thermal Regime ◽  
Ground Penetrating Radar ◽  
Thermal Conditions ◽  
Radio Waves ◽  
King George Island ◽  
Ablation Area ◽  
Ground Penetrating ◽  
Subglacial Meltwater ◽  
Strong Scattering

ABSTRACT. We present the results of a high-frequency Ground Penetrating Radar (GPR) surveys carried out during the ablation season of 2011, in Wanda Glacier, King George Island (KGI), Antarctica, aimed to determine its internal structure and thermal regime. GPR data were collected along 17 longitudinal and transversal sections in the ablation area in January 2011. Migrated and topographically corrected radar sections show strong internal reflectors in firn layer. Similar internal structure is observed in other glaciers in KGI. Strong scattering of radio waves are attributed to supraglacial, englacial and subglacial meltwater channels and constitutes further evidence that the ice in the ablation area of this glacier is temperate. Because of its small size (1.5 km2) and thermal conditions, Wanda Glacier responds rapidly to climatic changes being relevant for environmental studies. Keywords: glaciology, thermal regime, glacial dynamic.    RESUMO. O trabalho apresenta resultados de dados de GPR de alta frequência obtidos durante a estação de ablação de 2001, na geleira Wanda, Ilha Rei George (KGI), Antártica, com o objetivo de determinar a estrutura interna e o regime termal. Dados de GPR foram coletados em 17 perfis longitudinais e transversais na área de ablação em janeiro de 2011. Perfis de radar topograficamente corrigidos e migrados mostram fortes refletores internos na camada de firn . Estruturas similares foram observadas em outras geleiras da KGI. Fortes espalhamentos das ondas de rádio são atribuídas a canais de água de degelo nas zonas subglaciais, supraglaciais, e englaciais e constituem evidências para que o gelo na zona de ablação seja temperado. Devido à sua pequena dimensão (1,5 km2) e condições termais, a geleira Wanda responde rapidamente as mudanças climáticas, o que é relevante para estudos ambientais. Palavras-chave: glaciologia, regime termal, dinâmica glacial. 

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Radio Waves Kill Insect Pests

1933 ◽  
Vol 148 (5) ◽  
pp. 272-273 ◽  
Author(s):  
J. H. Davis
Keyword(s):  
Insect Pests ◽  
Radio Waves

Ultra Short Baseline (USBL) Calibration for Positioning of Underwater Objects

2019 ◽  
Vol 2 (2) ◽  
pp. 73-85
Author(s):  
Bagus Septyanto ◽  
Dian Nurdiana ◽  
Sitti Ahmiatri Saptari
Keyword(s):  
Acoustic Wave ◽  
Scale Factor ◽  
Positioning System ◽  
Radio Waves ◽  
Short Baseline ◽  
Error Angle ◽  
Satellite Navigation System ◽  
The Earth ◽  
Underwater Positioning ◽  
Radio Signals

In general, surface positioning using a global satellite navigation system (GNSS). Many satellites transmit radio signals to the surface of the earth and it was detected by receiver sensors into a function of position and time. Radio waves really bad when spreading in water. So, the underwater positioning uses acoustic wave. One type of underwater positioning is USBL. USBL is a positioning system based on measuring the distance and angle. Based on distance and angle, the position of the target in cartesian coordinates can be calculated. In practice, the effect of ship movement is one of the factors that determine the accuracy of the USBL system. Ship movements like a pitch, roll, and orientation that are not defined by the receiver could changes the position of the target in X, Y and Z coordinates. USBL calibration is performed to detect an error angle. USBL calibration is done by two methods. In USBL calibration Single Position obtained orientation correction value is 1.13 ̊ and a scale factor is 0.99025. For USBL Quadrant calibration, pitch correction values is -1.05, Roll -0.02 ̊, Orientation 6.82 ̊ and scale factor 0.9934 are obtained. The quadrant calibration results deccrease the level of error position to 0.276 - 0.289m at a depth of 89m and 0.432m - 0.644m at a depth of 76m

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