All-weather volume imaging of the boundary layer and troposphere using the MU radar

Worthington, R. M.

doi:10.5194/angeo-22-1407-2004

Cited by 11 publications

(17 citation statements)

References 18 publications

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“…This result is compatible with the more intermittent and inhomogeneous characteristics of the weakly stable upper troposphere (e.g. Worthington, 2004). Thus, the averaging procedure affects more significantly the quality of the comparisons of the profiles at tropospheric heights.…”

Section: Profilessupporting

confidence: 73%

Comparisons of refractive index gradient and stability profiles measured by balloons and the MU radar at a high vertical resolution in the lower stratosphere

et al. 2007

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Abstract.Many experimental studies have demonstrated that VHF Stratosphere-Troposphere (ST) radar echo power is proportional to the generalized refractive index gradient squared M 2 when using a vertically oriented beam. Because humidity is generally negligible above the tropopause, VHF ST radars can thus provide information on the static stability (quantified by the squared Brunt-Väisälä frequency N 2 ) at stratospheric heights and this capability is useful for many scientific applications. Most studies have been performed until now at a vertical resolution of 150 m or more. In the present paper, results of comparisons between radar-and (balloon borne) radiosonde-derived M 2 and N 2 are shown at a better vertical resolution of 50 m with the MU radar (34.85 • N, 136.15 • E; Japan) by benefiting from the range resolution improvement provided by the multifrequency range imaging technique, using the Capon processing method. Owing to favorable winds in the troposphere, the radiosondes did not drift horizontally more than about 30 km from the MU radar site by the time they reached an altitude of 20 km. The measurements were thus simultaneous and almost collocated. Very good agreements have been obtained between both high resolution profiles of M 2 , as well as profiles of N 2 . It is also shown that this agreement can still be improved by taking into account a frozenin advection of the air parcels by a horizontally uniform wind. Therefore, it can be concluded that 1) the range imaging technique with the Capon method really provides substantial range resolution improvement, despite the relatively weak Signal-to-Noise Ratios (SNR) over the analyzed region of the lower stratosphere, 2) the proportionality of the radar echo power to M 2 at a vertical scale down to 50 m in the lower stratosphere is experimentally demonstrated, 3) the MU radar can provide stability profiles with a vertical resolution of 50 m at heights where humidity is negligible, 4) stable Correspondence to: H. Luce (hubert.luce@lseet.univ-tln.fr) stratospheric layers as thin as 50 m or less have at least a horizontal extent of a few km to several tens of kilometers and can be considered as frozenly advected over scales of a few tens of minutes.

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Section: Profilessupporting

confidence: 73%

Comparisons of refractive index gradient and stability profiles measured by balloons and the MU radar at a high vertical resolution in the lower stratosphere

et al. 2007

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“…Other authors (e.g. Worthington, 2004;Adachi et al, 2005;Ishihara et al, 2006) have reported inhomogeneities between the observations made in different beam pointing directions under convective conditions. Based on the above experiences, it was anticipated that the distribution of full complementary-beam-continuity factor values would be mostly concentrated around zero, but with a small spread at much larger values.…”

Section: Exploitation Of Complementary-beam Informationmentioning

confidence: 99%

Validation of a new signal processing scheme for the MST radar at Aberystwyth

et al. 2008

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Abstract. This paper describes a new signal processing scheme for the 46.5 MHz Doppler Beam Swinging windprofiling radar at Aberystwyth, in the UK. Although the techniques used are similar to those already described in literature -i.e. the identification of multiple signal components within each spectrum and the use of radial-and time-continuity algorithms for quality-control purposes -it is shown that they must be adapted for the specific meteorological environment above Aberystwyth. In particular they need to take into account the three primary causes of unwanted signals: ground clutter, interference, and Rayleigh scatter from hydrometeors under stratiform precipitation conditions. Attention is also paid to the fact that short-period gravitywave activity can lead to an invalidation of the fundamental assumption of the wind field remaining stationary over the temporal and spatial scales encompassed by a cycle of observation. Methods of identifying and accounting for such conditions are described. The random measurement error associated with horizontal wind components is estimated to be 3.0-4.0 m s −1 for single cycle data. This reduces to 2.0-3.0 m s −1 for data averaged over 30 min. The random measurement error associated with vertical wind components is estimated to be 0.2-0.3 m s −1 . This cannot be reduced by time-averaging as significant natural variability is expected over intervals of just a few minutes under conditions of short-period gravitywave activity.

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“…Fig. 3c of Worthington (2004). Nevertheless, radiosondes show a convective boundary layer to ∼1.3 km AGL in Figs.…”

Section: Introductionmentioning

confidence: 99%

“…The beam transmitted by the entire radar array switches direction every 400 µ s to volume-image the atmosphere, with range resolution 150 m and transmitted beamwidth 3.6 • . Measurement time is 64 beams ×400 µ s inter-pulse-period ×1 incoherent integration ×2 coherent integrations ×128 FFT points=6.55 s. The MU radar mode is identical to 15-16 July 2002in Worthington (2004. Volumeimaging refers only to three-dimensional measurement of atmosphere, not e.g.…”

Section: Introductionmentioning

confidence: 99%

VHF volume-imaging radar observation of aspect-sensitive scatterers tilted in mountain waves above a convective boundary layer

Worthington

2005

Ann. Geophys.

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Abstract. Thin stable atmospheric layers cause VHF radars to receive increased echo power from near zenith. Layers can be tilted from horizontal, for instance by gravity waves, and the direction of VHF "glinting" is measurable by spatial domain interferometry or many-beam Doppler beam swinging (DBS). This paper uses the Middle and Upper atmosphere (MU) radar, Shigaraki, Japan as a volume-imaging radar with 64-beam DBS, to show tilting of layers and air flow in mountain waves. Tilt of aspect-sensitive echo power from horizontal is nearly parallel to air flow, as assumed in earlier measurements of mountain-wave alignment. Vertical-wind measurements are self-consistent from different beam zenith angles, despite the combined effects of aspect sensitivity and horizontal-wind gradients.

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All-weather volume imaging of the boundary layer and troposphere using the MU radar

Cited by 11 publications

References 18 publications

Comparisons of refractive index gradient and stability profiles measured by balloons and the MU radar at a high vertical resolution in the lower stratosphere

Comparisons of refractive index gradient and stability profiles measured by balloons and the MU radar at a high vertical resolution in the lower stratosphere

Validation of a new signal processing scheme for the MST radar at Aberystwyth

VHF volume-imaging radar observation of aspect-sensitive scatterers tilted in mountain waves above a convective boundary layer

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