A Generalized Approach to Interference Invariant of the Hydroacoustic Field in Deep and Shallow Seas

A new definition of the hydroacoustic field invariant based on a stable estimate of the invariance of orthogonal projections of the sound-pressure-phase gradients on the “distance–frequency” plane is introduced. Such a definition generalizes the concept of an invariant to all existing zones of shallow and deep seas including the near and far zones of illumination of the deep sea in which it is impossible to estimate and apply the Chuprov interference invariant. In the zone of existence of the Chuprov invariant, its values almost coincide with the values of the new invariant.