Scripps Institution of Oceanography

SIO Reference 58-47. The conventional form of the equation of transfer in radiative transfer theory is tailored principally to fit the needs of theoretical investigations. The quantities appearing in the equation, while readily measurable, do not allow the equation to express their interconnections in a way which is helpful to the intuition of the experimenter. The purpose of this note is to present a reformulation of the equation of transfer which appears to be of help in the task of collating and understanding the experimentally obtained properties of the optical medium. Quite interestingly, this reformulation appears to hold the key to the solution of one of the long-standing theoretical problems of this field, namely the problem of the existence and form of the asymptotic radiance distribution in an arbitrary medium with arbitrary external lighting conditions. The solution of this problem, in turn, supplies a raft of rules and laws about the behaviour of the light field in optically deep media which promise to be of additional help to the experimenter in understanding his data, and in applying them to practical problems. In this note, we will be concerned primarily with the motivation for the reformulation of the transfer equation, and with the details of the derivation of the equation. The discussion will be limited to some immediate practical examples of its use. The complete discussion of the solution of the asymptotic radiance distribution problem is reserved for a subsequent note,