In this work, we derive high order Equivalent Absorbing Boundary Conditions EABCs that model the propagation of waves in semi-infinite bilayered acoustic media. Our motivation is to restrict the computational domain in the simulation of seismic waves that are propagated from the earth and transmitted to the stratified heterogeneous media composed by ocean and atmosphere. These EABCs are adapted to Hagstrom-Warburton ABCs and appear as first and second order of approximation with respect to a small parameter involved in a multiscale expansion. Computational tests illustrate the accuracy of the first approximate model with respect to the small parameter.
