  The paper presents the analysis of pulsed sound fields recorded by a vertical
array in the Lake Kinneret (Israel). The transition from the traditional
representation of the complex amplitude of the received field as a function of
depth and time to a function representing the field distribution in the phase
space `depth - angle - time' is considered. Due to the absence of multipath and
problems with caustics, the sound field distribution in phase space is less
sensitive to environmental disturbances and therefore more predictable than in
configuration space. The transition is carried out using the coherent state
expansion developed in the quantum theory. The found distribution of the field
intensity in the phase space agrees with the calculation performed with an
idealized environmental model. It is shown that this distribution can be taken
as the input for solving the problem of source localization. The results of
data processing demonstrate the possibility of using the coherent state
expansion for isolating the field component formed by a given beam of rays.
