摘要:

The energy transfer due to weak nonlinear interactions in random wave fields is reinterpreted in terms of a hypothetical ensemble of interacting particles, antiparticles, and virtual particles. In the particle picture, the interactions can be conveniently described by Feynman diagrams, which may be regarded either as branch diagrams of the perturbation expansion or as collision diagrams. The derivation of the transfer expressions can then be reduced to a few general rules for the construction of the diagrams and the associated collision cross sections. The representation follows closely the standard treatment of nonlinear lattice vibrations, but the particle picture differs from the usual phonon interpretation of lattice waves. It has the unrealistic property that the energies and number densities of antiparticles are negative. This is offset by simpler interaction rules and a closer correspondence between the perturbation graphs and collision diagrams. The method is illustrated for scattering processes in the oceanic wave guide involving surface and internal gravity waves, horizontal currents (turbulence), seismic waves, and bottom irregularities.

ISSN:8755-1209    

DOI:10.1029/RG004i001p00001

年代:1966

数据来源: WILEY

摘要:

The past two decades have seen a number of successful applications of the theory of wave propagation in stratified mediums to ocean acoustics, having the straightforward objective of comparing an observed acoustical field, in as much detail as possible, with that calculated under suitable simplifying assumptions. But this approach has intrinsic limitations due to the fact that the ocean is not the fixed, simply stratified medium assumed in the theory. It is an irregular, fluctuating medium; therefore a completely deterministic attitude toward it is impossible. It appears that future advances in our understanding of ocean acoustics must rely heavily on statistical and stochastic theory and on the considered use of modern data‐processing methods. In this spirit, we suggest a fundamentally new approach to long‐range, low‐frequency acoustic propagation experiments, consisting of spectrum‐analyzing the square of the acoustical pressure versus range for interference wavelengt

ISSN:8755-1209    

DOI:10.1029/RG004i001p00033

年代:1966

数据来源: WILEY

摘要:

More than 1000 deep crustal seismic refraction profiles have been compiled in a standard format which gives the location of the profile, summary of seismic results, topographic and physiographic characteristics, reference to where the full interpretation can be found, and, if available, some information on the gravity anomalies. Several maps are given, showing the depths to the Mohorovicic discontinuity as determined from these profiles.

ISSN:8755-1209    

DOI:10.1029/RG004i001p00041

年代:1966

数据来源: WILEY

摘要:

The review of the recent advances made in the western part of the world in the theory of radiative transfer relates to the studies of the only physically realistic models of a planetary atmosphere in which both multiple scattering and polarization are taken fully into consideration. In the mathematical formulation of radiative transfer problems, the meaningful advances have been made in the emphasis on better physical interpretation of the mathematical analysis and of the used parameters that have resulted in the renaissance of the original Chapman's approach, based on a source matrix and on the solution of auxiliary equations for this matrix. This procedure is demonstrated in the derivation of this equation for the inhomogeneous case of imperfect scattering (i.e., the case with absorption and scattering with variable albedo of single scattering within the medium). The integrodifferential equations for the reflection and transmission matrices for this case are presented, and their reduction is demonstrated for the separable phase matrix in which the directional parameters of the incident and scattered radiation can be separated. For such a phase matrix the integrodifferential equations can be reduced to the solution of a pair of integral equations forXandYmatrices that for homogeneous cases assume forms identical to those for theXandYfunctions introduced by Chandrasekhar. Considerable advances have been made in the analysis of these functions, especially in the solution of the problem of their non‐uniqueness. With the use of the theory of singular integral equations applied to the nonlinear integral equation forXandYfunction, transformed into a singular form, a method has been recently developed that enables rapidly converging iteration for large optical thickness, leading even to asymptotic expressions for large τ. The review is concluded with the list of problems that can be expected to be solved in the near future without great or basic difficulti

ISSN:8755-1209    

DOI:10.1029/RG004i001p00101

年代:1966

数据来源: WILEY

ISSN:8755-1209    

DOI:10.1029/RG004i001p00112

年代:1966

数据来源: WILEY