Accession Number : ADP006379

Title :   Parabolic Equation Modelling of Backscatter from the Rough Sea Surface,

Corporate Author : RUTHERFORD AND APPLETON LABS CHILTON (UNITED KINGDOM)

Personal Author(s) : Levy, M. F.

Report Date : SEP 1991

Pagination or Media Count : 10

Abstract : This paper presents a physically based numerical method for calculating sea clutter at low grazing angles for microwave frequencies. Sea clutter is modelled as a two-scale phenomenon: at low grazing angles, the backscattered energy is generated by ripples on the sea surface. A first order perturbation method gives the backscatter from a small patch of surface, as a function of the angle of incidence and of the magnitude of the incident field. Returns from a clutter cell are obtained by incoherent summation of these echoes. Shadowing and tilting effects due to the larger scale components of the sea surface are modelled using a finite difference implementation of the parabolic equation method, which also deals with atmospheric refraction effects. Realizations of the sea surface with the desired spectral characteristics are generated with a Monte Carlo method. Results are presented at S band and X-band for a variety of propagation conditions.

Descriptors :   *SEA CLUTTER, *OCEAN SURFACE, *RADAR, ANGLE OF INCIDENCE, ANGLES, ATMOSPHERIC REFRACTION, ATMOSPHERICS, CELLS, CLUTTER, ECHOES, ENERGY, EQUATIONS, FUNCTIONS, GRAZING, MICROWAVES, MONTE CARLO METHOD, OCEANS, PROPAGATION, REFRACTION, RIPPLES, SCALE, X BAND, BACKSCATTERING, ELECTROMAGNETIC SCATTERING, SURFACE ROUGHNESS, ELECTROMAGNETIC WAVE PROPAGATION, SEA STATES, TARGET DETECTION, MILITARY EQUIPMENT.

Subject Categories : Active & Passive Radar Detection & Equipment
      Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE