James Strong, Chair of the Working Group on Marine Habitat Mapping (WGMHM)
'In marine science, backscatter typically refers to the reflection of soundwaves back towards their source. This reflectance is usually measured as an acoustic intensity (at a known reference angle). The time delay between a soundwave being emitted, bouncing off a seabed or mid-water object, and being received provides a measure of range (e.g. depth) – this principle forms the basis of 'sonar' (SOund Navigation And Ranging).
The emitted soundwave also loses intensity through scattering as it travels – this is detectable as acoustic backscatter. Particles in the water column partially scatter the soundwave but the majority this occurs at the seabed. The scattering is influenced by the size, shape and composition of the seabed. This information is extremely important for estimating the nature of the seabed and predicting the seabed habitats present. As such, marine habitat mapping surveys use sophisticated 'side-scan' and 'multi-beam' sonars to collect both range (depth) and backscatter (seabed texture and likely composition) simultaneously.'