Multiwavelength backscatter from the clear atmosphere

Hardy, Kenneth R.; Atlas, David; Glover, Kenneth M.

doi:10.1029/jz071i006p01537

Cited by 74 publications

(21 citation statements)

References 20 publications

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“…The combined wind and phase data (section 4) suggested that dominant signal contributions were frequently propagated via a low layer oflimited vertical extent. Supporting observations of tropospheric layer structure by Atlas et al (1966) and Hardy et al (1966) using radar backscatter, and by Lane (1966) using radar and radio refractometers, stimulated analysis of a thin, turbulent scattering layer. Using 7) (with sin 2 f3 = 1) and Gaussian antenna patterns, the "Doppler spectra" of figure 12 were computed from (5).…”

Section: Doppler Shift Modelmentioning

confidence: 71%

Observation of Wind‐Produced Doppler Shifts in Tropospheric Scatter Propagation

et al. 1968

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Persistent average frequency shifts obtained from phase data have been consistently observed on a 230-km closed-loop troposcatter circuit when the antennas were synchronously pointed off the great-circle azimuth. The magnitude of the "Doppler shift" systematically increases with the antenna pointing angle from the great circle. The sign of the Doppler shift reverses across the great circle and depends upon the direction of the crosspath wind simultaneously observed in the lower common volume. Average Doppler shift data are presented for several fixed-antenna-offset and antenna-beamswinging experiments conducted under varied meteorological conditions. Observations are interpreted in terms of atmospheric "scatterers" drifting across the path at the average crosspath wind speed. A model based on phase geometry is derived for the average Doppler shift and for Doppler spectra in terms of the crosspath wind velocity, antenna patterns and propagation mechanism.It is concluded that Doppler frequencies observed with a bistatic transhorizon microwave system depend primarily upon crosspath wind speed and the prevailing atmospheric structure. Crosspath motions thus appear to be an effective source of interference fading in tropospheric transhorizon propagation.

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Section: Doppler Shift Modelmentioning

confidence: 71%

Observation of Wind‐Produced Doppler Shifts in Tropospheric Scatter Propagation

et al. 1968

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“…These layers usually correspond in height to regions having sharp vertical gradients in refractive index. Additional evidence for the existence of clear-air radar layers associated with large variations of refractive index has been given by Saxton et al (1964), Hardy et al (1966), and Kropfli et al (1968). Multiple stratifications have been reported recently by Ottersten (1969a), Katz (1969), Crane (1970), Kropfti (1971) and Starr and Browning (1972).…”

Section: Backscatteringmentioning

confidence: 85%

Radar and sodar probing of waves and turbulence in statically stable clear-air layers

Óttersten

Hardy

Little³

1973

Boundary-Layer Meteorol

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Abstract. This paper reviews the remote sensing of waves and turbulence in statically stable atmospheric layers, utilizing sodar and microwave radar echoes from the small-scale inhomogeneities in gaseous refractive index caused by localized fluctuations in temperature, humidity, and velocity. Scattering theory and sounding methodology are reviewed briefly, and the relative performance of typical radar and sodar systems compared.The main section of the paper takes the form of a summary and discussion of experimental progress since 1969, showing how the echo patterns obtained may be applied to the interpretation of multiple layering, gravity waves, internal fronts and the details of dynamic instability and the genesis of turbulence in stably stratified shear layers. In addition, methods for the measurement of the intensity of the small-scale (~ ~./2) variability of wind, temperature and water vapor from the observed radar or sodar echo intensities, and the use of Doppler techniques for the measurement of mean velocity and turbulence are discussed.

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“…These radars are also sensitive to scattering particles (precipitation). These scattering mechanisms (Bragg, Fresnel and Raleigh) have been studied by some of the investigators (Booker and Gorden, 1950;Chisholm et al, 1955;Probert-Jones, 1962;Lane and Sollum, 1965;Hardy et al, 1966;Kropfli et al, 1968;Lane, 1969;Belrose, 1970;Evans, 1974;Gage and Green, 1978;Röttger and Liu, 1978;Fukao et al, 1978;Röttger and Vincent, 1978) from the observed radar echo power. Moreover, the contribution of water vapour to n is more for radio waves than for optical frequencies (Battan, 1973), particularly in the lower atmosphere up to 10 km.…”

Section: Introductionmentioning

confidence: 99%

Estimation of temperature and humidity from MST radar observations

Mohan

Rao

et al. 2001

Ann. Geophys.

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Abstract.Retrieval of vertical profiles of temperature and humidity parameters using a VHF radar is described in this paper. For this, Indian MST radar located at Gadanki (13.5• N, 79.2 • E) has been operated in a special mode. First, vertical velocities are collected continuously using the radar and are subjected to Fast Fourier Transform (FFT) analysis to obtain Brunt-Väisälä oscillations. From the measured BruntVäisälä oscillations, temperature profile is obtained from the radar observations following Revathy et al. (1996). The various terms required for the retrieval of vertical profiles of humidity are the eddy dissipation rate, ε, the volume reflectivity, η, and the potential refractive index gradient, M . The eddy dissipation rate, ε, is calculated from the spectral width after removing the effects due to non-turbulence. The volume reflectivity, η, of the turbulence scattering is calculated using the signal-to-noise ratio as a function of height. The potential refractive index gradient, M , is evaluated using the measured Brunt-Väisälä oscillations, the eddy dissipation rate and the volume reflectivity, η. Vertical profiles of humidity are retrieved following Tsuda (1997) using the radar derived temperature as well as the balloon measured temperature and are compared with the humidity as measured by the radiosonde. The sign of the potential refractive index gradient, M , is taken from the simultaneous measurements of balloon soundings. The retrieved vertical profiles of temperature and humidity have been compared with the radiosonde data, which are released simultaneously with the radar observations at the radar site. A fairly good comparison is seen between the two measurements on some days and there are some discrepancies on some other days. The strengths and limitations in estimating the vertical profiles of temperature and humidity from the radar observations are discussed.

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Multiwavelength backscatter from the clear atmosphere

Cited by 74 publications

References 20 publications

Observation of Wind‐Produced Doppler Shifts in Tropospheric Scatter Propagation

Observation of Wind‐Produced Doppler Shifts in Tropospheric Scatter Propagation

Radar and sodar probing of waves and turbulence in statically stable clear-air layers

Estimation of temperature and humidity from MST radar observations

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