DIFFRACTION OF P BY THE CORE: A STUDY OF LONG-PERIOD AMPLITUDES NEAR THE EDGE OF THE SHADOW

Abstract

Theoretical expressions for the amplitude of P-waves in the neighborhood of the core shadow boundary have been formulated and evaluated by computer. Comparison with 2.5 second data of Sacks confirms his determination of the shadow position at 96.5 degrees. A square root frequency scaling law is found for the high frequency diffraction pattern, and permits use of the Fresnel integral function at short periods. Long-period amplitude data for three paths have been spectrum analyzed and compared against the theoretical amplitude dropoff going into the shadow. The agreement is about as good as the data will permit, and no indication is found at these periods of a low-amplitude defocused region at 90 degrees to 96 degrees, after diffraction has been accounted for.

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Document Details

Document Type
Technical Report
Publication Date
Jun 30, 1968
Accession Number
AD0674606

Entities

People

  • Lawrence M. Cathles
  • Robert A. Phinney

Organizations

  • Princeton University

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Agreements
  • Boundaries
  • Data Analysis
  • Diffraction
  • Distortion
  • Frequency
  • Fresnel Integrals
  • Fresnel Zones
  • Geometry
  • Integrals
  • Measurement
  • North America
  • Phase Velocity
  • Scaling Laws
  • Spectra
  • Square Roots
  • Time Domain

Fields of Study

  • Physics

Readers

  • Atmospheric Science / Meteorology, specifically Wind Wave Turbulence.
  • Wave Propagation and Nonlinear Chaotic Dynamics.