A technique for the remote sensing of hail with an S-band dual linear polarization radar is described. The method employs a new signal HDR, which derived from disdrometer measurements raindrop size distributions. Experimental measurements, made in Colorado National Center Atmospheric Research's (NCAR) CP-2 system, are used to demonstrate two major hailstorms.

Four polarimetric measurands were collected in the stratiform region of a mesoscale convective system. The four are reflectivity factor, differential reflectivity, correlation coefficient between orthogonal copolar echoes, and propagation constant. Most striking is signature large aggregates (about 10 mm size) seen phase through melting layer. Another significant feature an abrupt notch that occurs towards bottom bright band. Aircraft observations one-dimensional cloud model used to explain...

This study explores the utility of polarimetric measurements for discriminating between hydrometeor types with emphasis on (a) hail detection and discrimination its size, (b) measurement heavy precipitation, (c) identification quantification mixed-phase hydrometeors, (d) ice forms. In particular, we examine specific differential phase, backscatter correlation coefficient vertically horizontally polarized waves, reflectivity, collected from a storm at close range. Three range–height cross...

The effects of melting and shedding hailstones on various polarimetric dual-wavelength radar observabies are examined. A model is used for oblate spheroidal composed an ice core a water coating. Single scattering illustrated using monodisperse size distributions having one particle per cubic meter. Resnlts exponential distributions, including Gaussian canting angle distribution, also given. It shown that can significantly affect the observahles that, by combining several observables,...

Conical graupel is modeled using sphere-cone-oblate spheroidal shapes for the purpose of computing their backscattering properties at a wavelength 10 cm in terms radar polarimetric observables, reflectivity factors, differential reflectivities and circular depolarization ratios. A shape distribution based on situ measurements used together with gamma (m=0, 2) size distributions computations; both wet dry are considered. Significant differences observables between cases noted effects canting...

Empirical relationships for estimating rainfall rate, liquid water content and median volume diameter from radar measurements of reflectivity factor differential are derived a disdrometer record highly variable, heavy event in central Illinois. Comparisons with representing exponential gamma model drop-size distributions made. Simulations, employing these Z-R estimation, performed. Statistical measures tabulated comparing results. These show an excellent agreement between the disdrometer-...

Abstract Multiparameter radar measurements were made during a heavy rainfall event accompanied by hail in Colorado. Rainfall rates R and accumulation Σ for this estimated using S-band specific differential phase KDP, reflectivity factor ZH, X-band attenuation AH3. These estimates compared with from ground-based rain gauge. Both R–KDP R–AH3 relations good agreement the gauge data, that is, less than 10% difference accumulations. The R–Z relation produced similar...

The differential reflectivity (Z DR ) radar signal contains information on the shape and alignment of ice phase hydrometeors. Under certain circumstances, then, this factor can be used to identify presence hail particles. Such interpretations require knowledge about scattering properties various types shapes hydrometeors, including ice, water‐coated graupel. These hydrometeors are examined for their obtained from computations using transition ( T matrix method Waterman an extension theory...

An attenuation correction procedure is proposed and evaluated by simulations using raindrop size distribution obtained from ground-based disdrometer measurements. The results show that under certain conditions it possible to retrieve C-band reflectivity factor (Z/sub H/) differential DR/) radar observables affected along rain-filled propagation paths. Rainfall rates estimated Z/sub H/ DR/ with without are compared determine the effects of capability account for it.< <ETX...

The electromagnetic scattering characteristics of several bullet-rosette ice crystal forms are computationally evaluated at 35-, 94-, and 220-GHz frequencies compared with those stellar crystals, hexagonal plates, columns. One the bullet rosettes is a planar four branches, other two spatial six eight branches. Two orientation models used, one represents highly oriented crystals for which side vertical incidence directions considered, represents: randomly (the direction does not affect this...

C-band dual-linear polarization radar observables are simulated from disdrometer measurements in rainfall and gamma-model raindrop-size distributions. It is shown that clustered certain sections of planes formed by selected pairs observables, such as (ZH, ZDR), ZDP), KDP), (ρ, ZDR). Measurements lying outside these cluster regions can be interpreted being ice- mixed-phase hydrometeors. Relationships for estimating rate R ZH, KDP, ZDR) derived, the latter to produce best results. An important...

Polarimetric scattering from cloud ice crystals modeled as hexagonal columns, plates and stellar are calculated at 94 220 GHz frequencies using the finite difference time domain (FDTD) method. Two orientation models considered, In first model long axes of columns broad surfaces parallel to horizontal plane randomly oriented on this plane. The second assumes uniform random in three dimensions (3-D). ratio backscattering cross sections exhibits a steady decrease with increasing size up about...

The presence of undetected mixed-phase precipitation or superimposed intense clutter can cause serious errors in the estimation rainfall rate and other parameters occurring radar scattering volume. To reduce avoid these it is necessary to distinguish between rain echo, that due types precipitation, echoes ground clutter. Multiparameter measurements may be exploited for this discrimination. In particular, demonstrated dual-linear polarization play a major role process. Sample data are...

A differential reflectivity radar technique for observing hailstorms is demonstrated using measurements obtained during the 13 June 1984 Denver hailstorm. The hail regions of storm are identified with signal. Histograms ZH and ZDR generated different heights in relative variation these parameters also determined. It observed that due to melting, mean values increase decreasing height below 0°C level (which around 2.6 km above ground level). Furthermore, at lower levels varies between −1 +2...

Abstract Two algorithms are presented for ice crystal classification using 95-GHz polarimetric radar observables and air temperature (T). Both based on a fuzzy logic scheme. Ice crystals classified as columnar (CC), planar (PC), mixtures of PC small- to medium-sized aggregates and/or lightly moderately rimed (PSAR), medium- large-sized PC, or densely graupel-like snow small lumpy graupel (PLARG), larger than about 2 mm (G). The 1D algorithm makes use Zh, Zdr, LDRhv, T, while the 2D...

Dual-polarization radar observables of cloud ice crystals are simulated at 94 and 220 GHz frequencies. Three crystal shapes considered: hexagonal columns, plates, stellar crystals. A gamma model size distribution a three dimensional (3D) canting used. The displayed as function elevation angle. linear depolarization ratios LDR/sub h/ v/, the circular ratio CDR, magnitude copolarized cross correlation coefficient /spl rho//sub hv/ found to be useful for differentiating columns from plates...

Electromagnetic scattering from raindrops at 94- and 140-GHz frequencies is investigated. The differences in the properties of spherical oblate spheroidal model are illustrated for side vertical incidence cases. Various backscattering propagation parameters evaluated using Marshall-Palmer, Joss thunderstorm, drizzle drop size distributions. Doppler spectrum substantially affected by raindrop shape. radar reflectivity specific attenuation not significantly affected.< <ETX...

The attenuation of a commercial satellite link signal at Ku-band is used for estimating rainfall rate along the path. Comparisons with accumulations obtained using simultaneous radar measurements same path show good agreement. This method can potentially be to complement other accumulation and rain gauges in urban settings areas complex terrain.

Power law relationships of the form R=aA/sup b/ are derived, where R is rainfall rate, and A 35-GHz specific attenuation A/sub h/ or differential /spl Delta/A=A/sub h/-A/sub v/, subscripts h v indicate horizontal vertical polarizations. The effects raindrop size distribution, canting, oscillation on these evaluated quantitatively. drop distributions (DSDs) obtained from ground-based disdrometer measurements three different geographical locations around world. R-A/sub relationship negligibly...

A novel FDTD scheme that can be used to effectively model the interaction of electromagnetic waves with bi-isotropic (BI) media is developed. This new technique exploits fact fields in a BI medium may decomposed into set two uncoupled waves, each which viewed as propagating an associated isotropic medium. The main advantages this approach are inherent simplicity resulting BI–FDTD scheme, and ability easily extend it include dispersive well bi-anisotropic materials. For purposes illustration,...

An analytical expression is derived for the reflection coefficient of a staircased air/dielectric interface. This then used to determine attenuation and propagation constants wave induced by staircasing. It demonstrated here that errors due staircasing increase as relative dielectric permittivity increased converges results an air-PEC

Differential reflectivity (Z DR ) and circular depolarization ratio (CDR) radar signals are directly related to each other the median drop size diameter of rainfall when sizes exponentially distributed. These polarization parameters examined for both static oscillating raindrop shapes along with their relationships rate liquid water content estimates derived from Z or CDR factor ( measurements. Propagation effects at S band wavelengths also considered shown be particularly important in

Bistatic dual-polarization radar parameters at S- and C-band frequencies are simulated for rain hail. The goal is to determine their potential discriminating the two precipitation types estimating of an exponential size distribution Raindrops hailstones modeled as oblate spheroids with canting distributions representing fall behavior. Three hailstone composition models used illustrate effects melting. Most bistatic significantly affected by amount liquid water in hailstones, which may prove...