Accession Number : ADA188720

Title :   On the Theory of Electromagnetic Scattering from a Raindrop Splash.

Descriptive Note : Memorandum rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Wetzel, Lewis B

PDF Url : ADA188720

Report Date : 31 Dec 1987

Pagination or Media Count : 45

Abstract : Electromagnetic scattering from a raindrop splash on a water surface is examined in terms of the splash structures that have been disclosed by high-speed photography. Of the three basic scattering features, the crown, the stalk, and the ring wave, the first two are modeled as dielectric cylinders, while the third is treated by a perturbation approximation. Cross section predictions based on these models are found to be in good agreement with Hansen's laboratory measurements of splash scattering. Procedures are given for extending these models to natural rain falling on calm water surfaces, although the present lack of sufficiently complete experimental data prevents direct verification of the theory. Nevertheless, a few qualitative conclusions can be drawn from the formalism: the major scattering feature is the stalk, and while the vertically polarized returns will have only a weak dependence on rain rate, the horizontally polarized returns will depend strongly on both the rain rate and the shape of the stalk (or drop) size distribution curves. Recognizing that comprehensive field measurements of splash scattering on calm water would be difficult to accumulate, several additional laboratory experiments are suggested. Keywords include: Rain splash scatter, Sea clutter, Radar clutter, Sea scatter, Rain scatter.

Descriptors :   *ELECTROMAGNETIC SCATTERING, *RAINFALL INTENSITY, *SPLASH, *RADAR REFLECTIONS, *RADAR REFLECTIONS, CROSS SECTIONS, CYLINDRICAL BODIES, DIELECTRICS, DISTRIBUTION CURVES, EXPERIMENTAL DATA, FIELD TESTS, HIGH SPEED PHOTOGRAPHY, LABORATORY PROCEDURES, LABORATORY TESTS, LOW STRENGTH, MEASUREMENT, MODELS, PERTURBATIONS, PREDICTIONS, RADAR CLUTTER, RAIN, RAINDROPS, RATES, SEA CLUTTER, STRUCTURES, SURFACES, WATER, WAVES, COMPARISON

Subject Categories : Electricity and Magnetism
      Active & Passive Radar Detection & Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE