A nonparametric SSB model, derived using the TOPEX altimeter, is analyzed to show a new decomposition of the form SSB=bHs+f(&sgr;o), where b is 0.03 and the function of radar cross section (&sgr;o) is an absolute second-order range correction residing outside the conventional nondimensional SSB model. Expected variability in the dominant bHs term and its ties to the long wave orbital velocity and shorter-scale slope variances are discussed using a physically-motivated restatement of recent EM bias theory. The geometry of steep near-breaking waves, neglected within current theory, is invoked as one plausible explanation for the observed Hs-independent SSB component. ¿ 2001 American Geophysical Union