Scale models of the ocean bottom exhibiting multiscale roughness having power-law form power-spectral density are useful for validation of deterministic and stochastic rough-surface scattering theories. Such scattering theories require accurate knowledge of the topography of the scale-model surface, which, at acoustic scales, can be measured on a twodimensional grid using a kinematic-resistive touch-trigger probe and represented by a digital elevation model. Both the discrete representation and

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... the physical measurement process introduce spectral artifacts. While the theoretical relationship describing spectral effects of the discrete representation is well known, this relationship is more complex for the physical measurement process. In the later case, spectral effects result from a combination of random measurement errors and fundamental limitations of probe measurement. Here, a numerical model of the physical measurement process is presented, which is used to simulate spectral effects of probe measurement. While random measurement errors can be controlled for and tend to introduce only an additive white-noise component into the measured power-spectral density, limitations of probe measurement are due to the finite size of the probe stylus and result in a systematic error in the measured power-spectral density for spatial wavenumbers above a critical wavenumber. Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 6 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18