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

Hirono, Motokazu; Luce, Hubert; Yamamoto, M.; Fukao, S.

doi:10.5194/angeo-22-717-2004

Cited by 17 publications

(4 citation statements)

References 14 publications

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“…Depending on the anisotropy of the refractive index irregularities at the Bragg scale, VHF radar echoes can strongly depend on the zenith angle of the radar beam direction, and, to a lesser extent, to the azimuth (e.g. Worthington et al, 1999;Hirono et al, 2004). A weak dependence of echo power with the radar beam direction strongly suggests that isotropic turbulent scatter is the dominant radar backscattering mechanism (e.g.…”

Section: Resultsmentioning

confidence: 99%

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

Wilson¹,

Luce²,

Hashiguchi³

et al. 2012

Preprint

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The present note addresses the detection of turbulence based on the Thorpe (1977) method applied to an atmosphere where saturation of water vapor occurs. The detection method proposed by Thorpe relies on the reordering in ascending order of a measured profile of a variable conserved through adiabatic processes (e.g. potential temperature). For saturated air, the reordering should be applied to a moist-conservative potential temperature, θ<sub>m</sub>, which is analogous to potential temperature for a dry (subsaturated) atmosphere. Here, θ<sub>m</sub> is estimated from the Brunt-Väisälä frequency derived by Lalas and Einaudi (1974) in a saturated atmosphere. The application to balloon data shows that the effective turbulent fraction of the troposphere can dramatically increase when saturation is taken into account. Preliminary results of comparisons with data simultaneously collected from the VHF Middle and Upper atmosphere radar (MUR, Japan) seem to give credence to the proposed approach

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Section: Resultsmentioning

confidence: 99%

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

Wilson¹,

Luce²,

Hashiguchi³

et al. 2012

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Worthington et al, 1999;Hirono et al, 2004). A weak dependence of echo power with the radar beam direction strongly suggests that isotropic turbulent scatter is the dominant radar backscattering mechanism (e.g.…”

Section: Resultsmentioning

confidence: 99%

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

et al. 2013

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Abstract. The present paper addresses the detection of turbulence based on the Thorpe (1977) method applied to an atmosphere where saturation of water vapor occurs. The detection method proposed by Thorpe relies on the sorting in ascending order of a measured profile of a variable conserved through adiabatic processes, (e.g. potential temperature). For saturated air, the reordering should be applied to a moist-conservative potential temperature, θm, which is analogous to potential temperature for a dry (subsaturated) atmosphere. Here, θm is estimated from the Brunt–Väisälä frequency derived by Lalas and Einaudi (1974) in a saturated atmosphere. The application to balloon data shows that the effective turbulent fraction of the troposphere can dramatically increase when saturation is taken into account. Preliminary results of comparisons with data simultaneously collected from the VHF Middle and Upper atmosphere radar (MUR, Japan) seem to give credence to the proposed approach.

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“…On the contrary, radar echoes of similar intensities in vertical and oblique beam directions are usually interpreted in terms of scattering from isotropic turbulence (e.g., Gage 1990). At 108-158 off zenith, scattering from isotropic turbulence is often the dominant backscatter mechanism in the troposphere (e.g., Tsuda et al 1988) but not in the lower stratosphere (e.g., Worthington et al 1999;Hirono et al 2004). Figure 1 shows time-height cross sections of radar reflectivity [more precisely, the radar echo power (dB) in arbitrary units after Capon processing and after correcting the range attenuation effects] using the vertical beam from 2205 LT 7 June 2006 to 0730 LT 8 June 2006 and for the altitude range of 1.32-18.0 km.…”

Section: Instruments Analysis Method and Datasetmentioning

confidence: 99%

MU Radar and Lidar Observations of Clear-Air Turbulence underneath Cirrus

Luce

Nakamura

Yamamoto

et al. 2010

Monthly Weather Review

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Turbulence generation mechanisms prevalent in the atmosphere are mainly shear instabilities, breaking of internal buoyancy waves, and convective instabilities such as thermal convection due to heating of the ground. In the present work, clear-air turbulence underneath a cirrus cloud base is described owing to coincident observations from the VHF (46.5 MHz) middle and upper atmosphere (MU) radar, a Rayleigh-Mie-Raman (RMR) lidar, and a balloon radiosonde on 7-8 June 2006 (at Shigaraki, Japan; 34.858N, 136.108E). Timeheight cross section of lidar backscatter ratio obtained at 2206 LT 7 June 2006 showed the presence of a cirrus layer between 8.0 and 12.5 km MSL. Downward-penetrating structures of ice crystals with horizontal and vertical extents of 1.0-4.0 km and 200-800 m, respectively, have been detected at the cirrus cloud base for about 35 min. At the same time, the MU radar data revealed clear-air turbulence layers developing downward from the cloud base in the environment of the protuberances detected by the RMR lidar. Their maximum depth was about 2.0 km for about 1.5 h. They were associated with oscillatory vertical wind perturbations of up to 61.5 m s 21 and variances of Doppler spectrum of 0.2-1.5 m 22 s 22 .Analysis of the data suggests that the turbulence and the downward penetration of cloudy air were possibly the consequence of a convective instability (rather than a dynamical shear instability) that was likely due to sublimation of ice crystals in the subcloud region. Downward clear-air motions measured by the MU radar were associated with the descending protuberances, and updrafts were observed between them. These observations suggest that the cloudy air might have been pushed down by the downdrafts of the convective instability and pushed up by the updrafts to form the observed protuberances at the cloud base. These structures may be virga or perhaps more likely mamma as reported by recent observations of cirrus mamma with similar instruments and by numerical simulations.

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

Cited by 17 publications

References 14 publications

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

MU Radar and Lidar Observations of Clear-Air Turbulence underneath Cirrus

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