Decoding seafloor acoustic signals
Nowadays, regulation of waste disposal at sea is in line with two recent conventions, namely the London Dumping Convention (1975), and the MARPOL Convention (1978). Yet, past dumping effects are still not very well explored, particularly the toxicity and bioaccumulation effects on water, sediment and biota. Urged by this, the SITAR project developed suitable oceanographic instrumentation and systems for assessing the risk posed by toxic dumpsites. In particular, focus was placed on those dumpsites in which an important part of the waste containers is buried within the sediment. More specifically, researchers generated acoustic methods and instrumentation for imaging of water containers of small dimension buried in unconsolidated sediments. One of the key project results was computer software for modelling of acoustic scattering from objects submerged in seawater. Apart from the module for forward modelling of scattering from objects on the seafloor or buried under it, the software comprises another module for identification of the scattering object. This is achieved by quantification of parameters including size, shape, orientation or acoustic contrast, so that the model-predicted scattered field fits well experimental data. The software includes two independent forward scattering models, one for computing the acoustic field scattered by a 3D object in a layered fluid-solid medium and a fast scattering model. The first model can be employed for evaluation of modelling accuracy, while the second can be employed in the object identification module. The software can be coupled with an emitter and a vertical array of receiver hydrophones for modelling and analysis of gathered scattering data. Despite this, the software also allows more general experimental configurations and runs on either single-host Linux systems or Linux clusters. The software is offered for commercial exploitation by the interested project partners together with external partners, on a case-by-case basis.