Correction of propagation effects in s-band circular polarisation-diversity radars

Bebbington, D.H.O.; McGuinness, R.; Holt, A.R.

doi:10.1049/ip-h-2.1987.0087

Cited by 14 publications

(7 citation statements)

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“…2a and b show KDP against ZHH at S-and C-band, respectively. At ZHH = 50 dBZ, KDp(S) varies between 1.5 and 2 okm-1 whereas K DP( C) varies between 2 and 4 okm-1 As is well known, this causes depolarisation of circularly polarised waves even at long wavelengths [7,8]. With intense rain rates and the possibility of long propagation paths, the use of circular polarisation for radars with only crosspolar reception (i.e.…”

Section: Note That Zhh• Zdr• Phv(o)mentioning

confidence: 99%

“…They have reported measurements of differential attenuaton and differential phase shift in rain at K-, Xand S-hands, using the range profile of W /W 2 were W is the complex crosscovariance between the co-and crosspolar (simultaneously) received signals and W 2 is the conventional reflectivity. These studies have been extended [7][8][9] principally at S-band where differential phase shift is dominant with both absolute and differential attenuation being negligible.…”

Section: Introductionmentioning

confidence: 99%

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Polarimetric radar signatures of precipitation at S and C-bands

Bringi

Chandrasekar

Meischner³

et al. 1991

IEE Proc. F Radar Signal Process. UK

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Polarimetric radar measurements in precipitation at S-and C-band frequencies are considered. Time series data were obtained from three advanced radars: the National Center for Atmospheric Research (NCAR) CP-2 radar, the National Severe Storms Laboratory's (NSSL) Cimarron radar, and the C-band Poldirad radar operated by the German Aerospace Research Establishment (DLR). Measurements of radar reflectivity, differential reflectivity Z DR, differential propagation phase cjJ DP, and the crosscorrelation between horizontal and vertical polarised waves are derived from time series data in rain, rain mixed with ice, and in the stratiform ice phase of convective storms. Raindrops are modelled as oblate in shape with a gamma form for their size distribution. The gamma parameters (N 0 , D 0 , m) are varied over an entire range encompassing a wide variety of rainfall types. The radar rain measurements are shown to be in good general agreement with the model rain simulations. By combining ZvR and cPvP it is possible to identify regions of mixed particle types, e.g. raindrops and hail, or ice crystals and snowflakes. The differential phase upon backscatter may be identified by examining the range profile of cPvP• giving additional clues as to the type and size of particles responsible for the backscatter.

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Section: Note That Zhh• Zdr• Phv(o)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polarimetric radar signatures of precipitation at S and C-bands

Bringi

Chandrasekar

Meischner³

et al. 1991

IEE Proc. F Radar Signal Process. UK

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“…This holds for a medium exhibiting reciprocity, includes the case of multiple forward scatter (coherent propagation). At S-band frequencies, it was shown [29] that the effective scattering matrix transformation induced by forward propagation through rain is very close to a unitary one of this form. Approximate time-reversal symmetry appropriately describes phase conjugation, a technique that is realised in modern optics to reverse a wavefront so that it substantially retraces its path.…”

Section: Consimilarity Transformationmentioning

confidence: 98%

On Mathematical and Physical Principles of Transformations of the Coherent Radar Backscatter Matrix

Bebbington

Carrea

2012

IEEE Trans. Geosci. Remote Sensing

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The congruential rule advanced by Graves for polarization basis transformation of the radar backscatter matrix is now often misinterpreted as an example of consimilarity transformation. However, consimilarity transformations imply a physically unrealistic antilinear time-reversal operation. This is just one of the approaches found in literature to the description of transformations where the role of conjugation has been misunderstood. In this paper, the different approaches are examined in particular in respect to the role of conjugation. In order to justify and correctly derive the congruential rule for polarization basis transformation and properly place the role of conjugation, the origin of the problem is traced back to the derivation of the antenna hight from the transmitted field. In fact, careful consideration of the role played by the Green's dyadic operator relating the antenna height to the transmitted field shows that, under general unitary basis transformation, it is not justified to assume a scalar relationship between them. Invariance of the voltage equation shows that antenna states and wave states must in fact lie in dual spaces, a distinction not captured in conventional Jones vector formalism. Introducing spinor formalism, and with the use of an alternate spin frame for the transmitted field a mathematically consistent implementation of the directional wave formalism is obtained. Examples are given comparing the wider generality of the congruential rule in both active and passive transformations with the consimilarity rule.

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“…However, effects of the transmission matrix on circular polarization radar observables resulted in depolarization of the transmitted wave due to pure differential phase shift in heavier rain that made it difficult to separate the backscatter effects from the effects due to propagation, as modelled in [22]. It was not until a decade later when Anthony Holt and David Bebbington from the UK re-analyzed the Alberta Research Council (ARC) data and devised a method for "correcting" the differential propagation phase that enabled recovery of the "intrinsic" backscatter elements of the coherency matrix [23]. In a follow-up article [24], Holt gave a simpler derivation and, in addition, provided algorithms to retrieve differential propagation phase and differential reflectivity (Z DR ).…”

Section: Brief Overview Of Electromagnetics In Dual-polarization Radamentioning

confidence: 99%

Polarization Weather Radar Development from 1970–1995: Personal Reflections

Bringi

Zrnic

2019

Atmosphere

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The modern era of polarimetric radar begins with radiowave propagation research starting in the early 1970s with applications to measurement and modeling of wave attenuation in rain and depolarization due to ice particles along satellite–earth links. While there is a rich history of radar in meteorology after World War II, the impetus provided by radiowave propagation requirements led to high-quality antennas and feeds. Our journey starts by describing the key institutions and personnel responsible for development of weather radar polarimetry. The early period was dominated by circularly polarized radars for propagation research and at S band (frequency near 3 GHz) for hail detection. By the mid to late 70s, a paradigm shift occurred which led to the dominance of linear polarizations with applications to slant path attenuation prediction as well as estimation of rain rates and inferences of precipitation physics. The period from the early 1980s to 1995 can be considered as the “golden” period of rapid research that brought in meteorologists, cloud physicists, and hydrologists. This article describes the evolution of this technology from the vantage point of the authors. Their personal reflections and “behind the scenes” descriptions offer a glimpse into the inner workings at several key institutions which cannot be found elsewhere.

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Correction of propagation effects in s-band circular polarisation-diversity radars

Cited by 14 publications

References 0 publications

Polarimetric radar signatures of precipitation at S and C-bands

Polarimetric radar signatures of precipitation at S and C-bands

On Mathematical and Physical Principles of Transformations of the Coherent Radar Backscatter Matrix

Polarization Weather Radar Development from 1970–1995: Personal Reflections

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