Polarimetric Method for Ice Water Content Determination

Ryzhkov, Alexander V.; Zrnić, Dúsan S.; Gordon, B. A.

doi:10.1175/1520-0450(1998)037<0125:pmfiwc>2.0.co;2

Cited by 92 publications

(78 citation statements)

References 21 publications

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“…The benefit of polarimetric data has been well demonstrated in quantitative rainfall estimation (e.g., Seliga and Bringi 1976;Ryzhkov et al 1998;Zrnic and Ryzhkov 1999) and precipitation type classification (e.g., Straka 1993;Vivekanandan et al 1999). Since PR data contain microphysical information, it is hypothesized that they can be used to improve the state estimation of microphysical fields, and hence, subsequent forecasts resulting from such initial conditions.…”

Section: Background and Motivationmentioning

confidence: 99%

“…Some polarimetric radar simulators already exist in the literature (Brandes et al 1995;Brandes et al 2004b;Zhang et al 2001;Vivekanandan et al 1994;Ryzhkov et al 1998;Huang et al 2005). However, they are either incomplete in terms of utilizing all available model parameters and state variables or are too expensive for use within DA systems.…”

Section: Introductionmentioning

confidence: 99%

“…Brandes et al (1995;, Zhang et al (2001) offer the expressions for rain. Vivekanandan et al (1994) and Ryzhkov et al (1998) propose formulae that can be applied to ice particles ranging from ice crystals to snow aggregates. Because of the lack of sufficient understating of the polarimetric measurements for ice and mixed phases because of their complex behaviors and non-linear interactions, general expressions that are applicable to each of the hydrometeor categories are generally unavailable.…”

Section: Introductionmentioning

confidence: 99%

“…Ryzhkov et al (1998) and Vivekanandan et al (1994) have proposed that polarimetric methods can estimate ice water content more accurately than the one that only uses reflectivity (Z H ). An accurate estimate of the amounts of hydrometeors and DSDs using polarimetric radar data can contribute to the improvement and verification of microphysical parameterizations in cloud and mesoscale models.…”

Section: Introductionmentioning

confidence: 99%

“…While many polarimetric radar emulators are mainly interested in single-phase hydrometeor concentration (Brandes et al 1995;Brandes et al 2004b;Ryzhkov et al 1998;Vivekanandan et al 1994;Zhang et al 2001;Capsoni et al 2001), only a handful of complete polarimetric radar emulators exist in the literature that utilizes all parameters available in the model. Huang et al (2005) developed a simulator based on T-matrix scattering calculations (Waterman 1969;Vivekanandan et al 1991 constant model is physically questionable because it assumes a high-density melting core with a low-density shell.…”

Section: Introductionmentioning

confidence: 99%

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State and parameter estimation

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Section: Background and Motivationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Orographic effects on snow deposition patterns in mountainous terrain

Mott¹,

et al. 2014

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Orographic lifting of air masses and other topographically modified flows induce cloud and precipitation formation at larger scales and preferential deposition of precipitation at smaller scales. In this study, we examine orographic effects on small-scale snowfall patterns in Alpine terrain. A polarimetric X-band radar was deployed in the area of Davos (Switzerland) to determine the spatial variability of precipitation. In order to relate measured precipitation fields to flow dynamics, we model flow fields with the atmospheric prediction model "Advanced Regional Prediction System. " Additionally, we compare radar reflectivity fields with snow accumulation at the surface as modeled by Alpine3D. We investigate the small-scale precipitation dynamics for one heavy snowfall event in March 2011 at a high resolution of 75 m. The analysis of the vertical and horizontal distribution of radar reflectivity at horizontal polarization and differential reflectivity shows polarimetric signatures of orographic snowfall enhancement near the summit region. Increasing radar reflectivity at horizontal polarization over the windward slopes toward the crest and downwind decreasing reflectivity over the leeward slopes is observed. The temporal variation of the location of maximum concentration of snow particles is partly attributed to the effect of preferential deposition of snowfall: For situations with strong horizontal winds, the concentration maximum is shifted from the ridge crest toward the leeward slopes. Qualitatively, we discuss the relative role of cloud microphysics such as the seeder-feeder mechanism versus atmospheric particle transport in generating the observed snow deposition at the ground.

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Estimating ice particle scattering properties using a modified Rayleigh‐Gans approximation

Clothiaux

Aydin

et al. 2014

JGR Atmospheres

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A modification to the Rayleigh-Gans approximation is made that includes self-interactions between different parts of an ice crystal, which both improves the accuracy of the Rayleigh-Gans approximation and extends its applicability to polarization-dependent parameters. This modified Rayleigh-Gans approximation is both efficient and reasonably accurate for particles with at least one dimension much smaller than the wavelength (e.g., dendrites at millimeter or longer wavelengths) or particles with sparse structures (e.g., low-density aggregates). Relative to the Generalized Multiparticle Mie method, backscattering reflectivities at horizontal transmit and receive polarization (HH) (Z HH ) computed with this modified Rayleigh-Gans approach are about 3 dB more accurate than with the traditional Rayleigh-Gans approximation. For realistic particle size distributions and pristine ice crystals the modified Rayleigh-Gans approach agrees with the Generalized Multiparticle Mie method to within 0.5 dB for Z HH whereas for the polarimetric radar observables differential reflectivity (Z DR ) and specific differential phase (K DP ) agreement is generally within 0.7 dB and 13%, respectively. Compared to the A-DDA code, the modified Rayleigh-Gans approximation is several to tens of times faster if scattering properties for different incident angles and particle orientations are calculated. These accuracies and computational efficiencies are sufficient to make this modified Rayleigh-Gans approach a viable alternative to the Rayleigh-Gans approximation in some applications such as millimeter to centimeter wavelength radars and to other methods that assume simpler, less accurate shapes for ice crystals. This method should not be used on materials with dielectric properties much different from ice and on compact particles much larger than the wavelength.

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Polarimetric Method for Ice Water Content Determination

Cited by 92 publications

References 21 publications

State and parameter estimation

State and parameter estimation

Orographic effects on snow deposition patterns in mountainous terrain

Estimating ice particle scattering properties using a modified Rayleigh‐Gans approximation

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