Radar and scattering parameters through falling hydrometeors with axisymmetric shapes

Abstract

Falling raindrops and other hydrometeors have, in general, nonspherical shapes and mean canting angles that are due to aerodynamic and gravitational forces. We use the T matrix and the quantum theory of angular momentum to compute extinction matrices, scattering and absorption cross sections, backscattering matrices, and, from these quantities, radar parameters. A monodisperse population of rain with axially symmetric distribution over orientations where the axis of symmetry is the local direction of air flow about the raindrops is considered. Oblate spheroids with axial ratios that depend on size and appropriate series of Chebyshev polynomials were assumed for definition of the shapes of raindrops. Computations were performed at common microwave frequencies for several temperatures, incidence angles, and degrees of particle wobble about a preferred orientation. Results reveal the importance of the role of orientation distribution and particle size and the shape of radar parameters in these computations for a region of moderate-sized raindrops.

Terminal settling velocity measurements of volcanic ash during the 2002–2003 Etna eruption by an X‐band microwave rain gauge disdrometer

“…Pludix is a rain gauge disdrometer that analyses the signal backscattered by hydrometeors [ Prodi et al , 2000; Battaglia et al , 2001]. It is an upward‐looking, bi‐static system (i.e.…”

New insights into real-time detection of tephra grainsize, settling velocity and sedimentation rate

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An Exact Solution of Coherent Wave Propagation in Rain Medium With Realistic Raindrop Shapes

“…There are two linear relation nominations, line A, with equation "a/b = 1−0.1a o " and line B, with (a/b = 1 − (0.41/4.5)a o ) which are used for axial ratio calculations. In these equations, a o is equal to the raindrop mean radius in millimeters and a nonlinear equation for axial ration is assumed as [6]:…”