  Contemporary high-resolution sonar systems use broadband pulses and long
arrays to achieve high resolution. It is important to understand effects that
high-resolution sonar systems might have on quantitative measures of the
scattered field due to the seafloor. A quantity called the broadband scattering
cross section is defined, appropriate for high-resolution measurements. The
dependence of the broadband scattering cross section, $\sigma_{bb}$ and the
scintillation index, $SI$ on resolution was investigated for one-dimensional
rough surfaces with power-law spectra and backscattering geometries. Using
integral equations and Fourier synthesis, no resolution dependence of
$\sigma_{bb}$ was found. The incoherently-averaged frequency-domain scattering
cross section has negligible bandwidth dependence. $SI$ increases as resolution
increases, grazing angle decreases, and spectral strength increases. This trend
is confirmed for center frequencies of 100 kHz and 10 kHz, as well as for
power-law spectral exponents of 1.5, 2, and 2.5. The hypothesis that local
tilting at the scale of the acoustic resolution is responsible for intensity
fluctuations was examined using a representative model for the effect of slopes
(inspired by the composite roughness approximation). It was found that slopes
are responsible in part for the fluctuations, but other effects, such as
multiple scattering and shadowing may also play a role.
