Modeling bistatic bottom scattering strength including a forward scatter lobe

An upgrade to bistatic scattering strength modelling that is based on the authors´ current understanding of bottom topographic scattering with an emphasis on modeling the `forward lobe´ where Lambert´s law fails quite significantly is reported. Low-frequency bottom scatter modeling is reviewed with particular emphasis on the issues of the forward scattered lobe. A specific model (a modified version of BISSM) is proposed, and the model´s advantages and limitations are discussed. The requirement for certain high-resolution geomorphic data needed to support the model is discussed. Like the original BISSM, the version does not modify the accepted form for diffuse scattering, but it does modify the form of the forward lobe