@article {Biescas2016, title = {{Synthetic Modeling for an Acoustic Exploration System for Physical Oceanography}}, journal = {Journal of Atmospheric and Oceanic Technology}, volume = {33}, number = {1}, year = {2016}, pages = {191{\textendash}200}, publisher = {American Meteorological Society}, abstract = {AbstractMarine multichannel seismic (MCS) data, used to obtain structural reflection images of the earth?s subsurface, can also be used in physical oceanography exploration. This method provides vertical and lateral resolutions of O(10?100) m, covering the existing observational gap in oceanic exploration. All MCS data used so far in physical oceanography studies have been acquired using conventional seismic instrumentation originally designed for geological exploration. This work presents the proof of concept of an alternative MCS system that is better adapted to physical oceanography and has two goals: 1) to have an environmentally low-impact acoustic source to minimize any potential disturbance to marine life and 2) to be light and portable, thus being installed on midsize oceanographic vessels. The synthetic experiments simulate the main variables of the source, shooting, and streamer involved in the MCS technique. The proposed system utilizes a 5-s-long exponential chirp source of 208 dB relative to 1 ?Pa at 1 m with a frequency content of 20?100 Hz and a relatively short 500-m-long streamer with 100 channels. This study exemplifies through numerical simulations that the 5-s-long chirp source can reduce the peak of the pressure signal by 26 dB with respect to equivalent air gun?based sources by spreading the energy in time, greatly reducing the impact to marine life. Additionally, the proposed system could be transported and installed in midsize oceanographic vessels, opening new horizons in acoustic oceanography research.}, issn = {0739-0572}, doi = {10.1175/JTECH-D-15-0137.1}, url = {http://dx.doi.org/10.1175/JTECH-D-15-0137.1}, author = {Biescas, Berta and Ruddick, Barry and Kormann, Jean and Sallares, Valenti and Nedimovi{\'c}, Mladen R and Carniel, Sandro} } @article {Kormann2010, title = {{Synthetic modelling of acoustical propagation applied to seismic oceanography experiments}}, journal = {Geophysical Research Letters}, volume = {37}, number = {6}, year = {2010}, month = {mar}, pages = {n/a{\textendash}n/a}, abstract = {Recent work shows that multichannel seismic (MCS) systems provide detailed information on the oceans{\textquoteright} finestructure. The aim of this paper is to analyze if high order numerical algorithms are suitable to accurately model the extremely weak wavefield scattered by the oceans{\textquoteright} finestructures. For this purpose, we generate synthetic shot records along a coincident seismic and oceanographic profile acquired across a Mediterranean salt lens in the Gulf of Cadiz. We apply a 2D finite-difference time-domain propagation model, together with second-order Complex Frequency Shifted Perfectly Matched Layers at the numerical boundaries, using as reference a realistic sound speed map with the lateral resolution of the seismic data. We show that our numerical propagator creates an acoustical image of the ocean finestructures including the salt lens that reproduces with outstanding detail the real acquired one. Copyright {\textcopyright} 2010 by the American Geophysical Union.}, issn = {00948276}, doi = {10.1029/2009GL041763}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77949835265\&partnerID=tZOtx3y1}, author = {Kormann, Jean and Cobo, Pedro and Biescas, Berta and Sallares, Valenti and Papenberg, Cord and Recuero, Manuel and Carbonell, Ram{\'o}n} } @article {Kormann2009, title = {{Modelling Seismic Oceanography Experiments by Using First- and Second-Order Complex Frequency Shifted Perfectly Matched Layers}}, journal = {Acta Acustica united with Acustica}, volume = {95}, number = {6}, year = {2009}, month = {nov}, pages = {1104{\textendash}1111}, abstract = {This work investigates the ability of modelling seismic oceanography experiments by using underwater acoustic propagation equations. Seismic oceanography tries to retrieve the fine structure of the ocean water masses by processing the acoustic waves reflected in the low-contrast interfaces of fronts, eddies, internal waves or thermohaline intrusions. Since the reflectivity of such interfaces is of order 10-3-10-4, the absorption capability of the numerical boundaries becomes crucial. Complex Frequency Shifted offers a better alternative to classical Perfectly Matched Layer formulation, but has not yet been extended to acoustic equations. Here, first- and second-order Complex Frequency Shifted Perfectly Matched Layers equations are proposed which can provide reflection coefficients of order 10-5. Therefore, a numerical Finite-Difference Time-Domain (FDTD) scheme combined with the proposed CFS-PML equations is able to model such experiments. {\textcopyright} S. Hirzel Verlag {\textperiodcentered} EAA.}, issn = {16101928}, doi = {10.3813/AAA.918242}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77149123321\&partnerID=tZOtx3y1}, author = {Kormann, Jean and Cobo, Pedro and Recuero, Manuel and Biescas, Berta and Sallares, Valenti} }