摘要：We formulate the radiative transfer of P - and S -wave energy from an isotropically radiating source in a two-dimensional infinite isotropic scattering medium.For a stable numerical calculation of seismogram envelopes, we take a semi-analytical approach: Energy densities of P and S waves are divided into three parts of the direct-wave terms, the single-scattering terms, and the multiple-scattering terms, and the first two terms and the last term are evaluated analytically and numerically, respectively.Concerning the single-scattering terms, the P- to- S and S -to- P single conversion scattering terms are expressed analytically with a complete elliptic integral of the first kind.The multiple-scattering terms are represented by a double integral with respect to frequency and wavenumber, and can be numerically evaluated by a discrete wavenumber summation and a Fast Fourier Transform.The results based on the numerical implementation are confirmed with an independent numerical calculation using the Monte Carlo method.Our formulation is also applied to consider the equilibration between P and S waves at larger lapse times.The equilibrated S -to- P energy ratio is reproduced and the equilibration time is first derived for two-dimensional cases.Our formulation will be a reference for the understanding of more complex cases. Key words Radiative transfer two-dimensional S -to- P energy ratio equilibration.
关键词：Radiative transfer ;two-dimensional ; S-to-P energy ratio ;equilibration
