Composite roughness theory is used to characterize Southern Ocean bottom ba
ckscatter (multibeam) data. Spectral parameters based on Helmholtz-Kirchhof
f's theory ill are determined From measured near-normal incidence values. A
splicing technique using Rayleigh-Rice theory  is employed beyond 20 de
grees incidence angles. Estimated roughness parameters for six deep ocean a
reas correlate with geology.