A new physical-geometric optics hybrid (PGOH) method is developed to compute the scattering and absorption properties of ice particles. This method is suitable for studying the optical properties of ice particles with arbitrary orientations, complex refractive indices (i.e., particles with significant absorption), and size parameters (proportional to the ratio of particle size to incident wavel...

We present a new approach to analyze the validation of weakly nonlinear geometric optics for entropy solutions of nonlinear hyperbolic systems of conservation laws whose eigenvalues are allowed to have constant multiplicity and corresponding characteristic fields to be linearly degenerate. The approach is based on our careful construction of more accurate auxiliary approximation to weakly nonli...

This paper considers the behavior of pulse-like solutions of length ε 1 to semilinear systems of hyperbolic partial differential equations on the time scale t = O(1/ε) of diffractive geometric optics. The amplitude is chosen so that nonlinear effects influence the leading term in the asymptotics. For pulses of larger amplitude so that the nonlinear effects are pertinent for times t = O(1), accu...

R esum e. La description classique du probl eme de l'optique g eom etrique est La-grangienne. Le passage a la repr esentation Eul erienne est possible mais, en pr esence de caustiques, ne permet pas de calculer la solution Lagrangienne compl ete. On pr esente le contexte math ematique du probl eme ainsi que quelques outils num eriques d evelop-p es pour lever cette limitation. Abstract. The cla...

In this companion paper to our study of amplification of wavetrains [CGW13], we study weakly stable semilinear hyperbolic boundary value problems with pulse data. Here weak stability means that exponentially growing modes are absent, but the so-called uniform Lopatinskii condition fails at some boundary frequency in the hyperbolic region. As a consequence of this degeneracy there is again an am...