Azimuth angle variations of specular reflection echoes in the lower atmosphere observed with the MU radar

Tsuda, Toshitaka; Gordon, William E.; Saito, H.

doi:10.1016/s1364-6826(96)00058-2

Cited by 30 publications

(29 citation statements)

References 4 publications

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“…The mean echo power value has been subtracted from the observed echo power at each height. A similar example was shown by Tsuda et al (1997) but at 6 degrees off zenith between 11 and 15.6 km and for observation intervals of 137 s. The corresponding wind shear direction measured by the MU radar is also indicated by a red curve. The radius of the red circles indicates the wind shear magnitude.…”

Section: Hti Plots Of Echo Powersupporting

confidence: 75%

“…The horizontal maps produce an image of the angular distribution of the facets' tilts smeared by the radar volume and time averaging. This idea is quite different from the hypothesis proposed by Tsuda et al (1997), who considered a model of monochromatic gravity waves with large horizontal wavelengths to explain the azimuthal dependence of echo power at a fixed zenith angle. However, the latter model cannot explain the skew of the distribution which can also produce sinusoidal variations when considering a fixed zenith angle.…”

Section: Introductionmentioning

confidence: 70%

“…This property was mainly observed in the lower stratosphere (Gage and Green, 1978;Röttger and Liu, 1978). Recently, the azimuthal dependence of echo power was thoroughly analyzed (Tsuda et al, 1997;Worthington and Thomas, 1997;Palmer et al, 1998), and it was found that the azimuth angle for which the power maximum is observed is strongly related to the horizontal wind shear direction. This property implies that the local wind shear affects the azimuthal distribution of the scatterers.…”

Section: Introductionmentioning

confidence: 98%

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Horizontal maps of echo power in the lower stratosphere using the MU radar

et al. 2004

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Abstract. In recent works, zenithal and azimuthal angle variations of echo power measured by VHF StratosphereTroposphere (ST) radars have been analyzed in detail using different radar multi-beam configurations. It was found that the azimuthal angle corresponding to maximum echo power is closely related to the direction of the horizontal wind shear. These properties indicate that local wind shear affects the tilt of the scatterers. Moreover, horizontal maps of echo power collected using a large set of beams steered pulse-to-pulse up to 40 degrees off zenith revealed that the power distribution pattern in the troposphere is often skewed. In this work, a three-dimensional description of echo power variations up to 24 degrees off zenith is shown for measurements in the lower stratosphere (i.e. up to approximately 20 km) using a "sequential multi-beam" (SMB) configuration. Such a description was not possible above the tropopause with classical multi-beam configurations because of the loss of radar sensitivity due to the limited integration time by the use of a large number of beams. This work attempts to complete previous descriptions of the phenomenon by some observations in the lower stratosphere discussed in association with complementary balloon measurements.

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Section: Hti Plots Of Echo Powersupporting

confidence: 75%

Section: Introductionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 98%

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Horizontal maps of echo power in the lower stratosphere using the MU radar

et al. 2004

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“…However, perturbations of the echo powers, varying with azimuth, could be caused by tilting of the anisotropic scattering layers or spatial variations over the distance between the radar beams. Tsuda et al (1997a) investigated the azimuth dependence of echo power, using radar beams in steps of 30 azimuth, with a constant 6 zenith angle. The azimuthal variations of echo power, typically up to 5 dB, were attributed to the tilting of layers by a monochromatic gravity wave.…”

Section: Introductionmentioning

confidence: 99%

Long-period unstable gravity-waves and associated VHF radar echoes

Worthington

Thomas

1997

Ann. Geophys.

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Abstract. VHF atmospheric radar is used to measure the wind velocity and radar echo power related to longperiod wind perturbations, including gravity waves, which are observed commonly in the lower stratosphere and tropopause region, and sometimes in the troposphere. These wind structures have been identi®ed previously as either inertia-gravity waves, often associated with jet streams, or mountain waves. At heights of peak wind shear, imbalances are found between the echo powers of a symmetric pair of radar beams, which are expected to be equal. The largest of these power di erences are found for conditions of simultaneous high wind shear and high aspect sensitivity. It is suggested that the e ect might arise from tilted specular re¯ectors or anisotropic turbulent scatterers, a result of, for example, Kelvin-Helmholtz instabilities generated by the strong wind shears. This radar power-di erence e ect could o er information about the onset of saturation in long-period waves, and the formation of thin layers of turbulence.

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“…Doviak et al (1996) and Holloway et al (1997) further considered the application of spaced antenna technique in situations of more isotropic turbulence, a condition more likely to hold only as generally true in the troposphere when using upper VHF, UHF, or higher frequencies. For example, in a typical study, Tsuda et al (1997) found significant aspect sensitivity at lower VHF in the troposphere and lower stratosphere when using the MU radar in Japan.…”

Section: Lataitis Slope Techniquementioning

confidence: 98%

MF and HF radar techniques for investigating the dynamics and structure of the 50 to 110 km height region: a review

Reid

2015

Prog. in Earth and Planet. Sci.

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The application of medium-frequency (MF) and high-frequency (HF) partial reflection radar to investigate the neutral upper atmosphere is one of the oldest such techniques still regularly in use. The techniques have been continuously improved and remain a robust and reliable method of obtaining wind velocities, turbulence intensities, electron densities, and measurements of atmospheric structure in the mesosphere lower thermosphere (MLT) region (50 to 110 km). In this paper, we review recent developments, discuss the strengths and weaknesses of the technique, and consider possible improvements.

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Azimuth angle variations of specular reflection echoes in the lower atmosphere observed with the MU radar

Cited by 30 publications

References 4 publications

Horizontal maps of echo power in the lower stratosphere using the MU radar

Horizontal maps of echo power in the lower stratosphere using the MU radar

Long-period unstable gravity-waves and associated VHF radar echoes

MF and HF radar techniques for investigating the dynamics and structure of the 50 to 110 km height region: a review

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