SACLANT ASW Research Centre

About: SACLANT ASW Research Centre is a based out in . It is known for research contribution in the topics: Waves and shallow water & Internal wave. The organization has 79 authors who have published 87 publications receiving 1237 citations.

Efficient global matrix approach to the computation of synthetic seismograms

Abstract: Summary. A numerically efficient global matrix approach to the solution of the wave equation in horizontally stratified environments is presented. The field in each layer is expressed as a superposition of the field produced by the sources within the layer and an unknown field satisfying the homogeneous wave equations, both expressed as integral representations in the horizontal wavenumber. The boundary conditions to be satisfied at each interface then yield a linear system of equations in the unknown wavefield amplitudes, to be satisfied at each horizontal wavenumber. As an alternative to the traditional propagator matrix approaches, the solution technique presented here yields both improved efficiency and versatility. Its global nature makes it well suited to problems involving many receivers in range as well as depth and to calculations of both stresses and particle velocities. The global solution technique is developed in close analogy to the finite element method, thereby reducing the number of arithmetic operations to a minimum and making the resulting computer code very efficient in terms of computation time. These features are illustrated by a number of numerical examples from both crustal and exploration seismology.

Non-Tidal Variability in the Chesapeake Bay and Potomac River: Evidence for Non-Local Forcing

Abstract: Non-tidal variability in the Chesapeake Bay and Potomac River, and its relation to atmospheric forcing, is examined from two-month sea level and bottom current measurements. The dominant sea level fluctuations in the Bay had a period of 20 days. and were the result of up-Bay propagation of coastal sea level fluctuations generated by the alongshore winds. Consequently, water was driven out of the Bay by the northward/up-Bay wind and driven into the Bay by the southward/down-Bay wind, through the coastal Ekman flux. There were also large sea level fluctuations at periods of 5 and 2.5 days. The 5-day fluctuations were driven by both the coastal sea level changes and the local lateral winds (Ekman effect). The 2.5-day fluctuations were seiche oscillations driven by the local longitudinal winds. In the Potomac River, the sea level fluctuations were induced non-locally by motions in the Bay; the associated volume fluxes appeared to have been confined to the upper layer. The near-bottom currents were ma...