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A method is developed for estimating the influence of surface waves and multiple scattering in water on delay and
broadening of light pulse signal propagating along the path: atmosphere - rough surface - sea water. The parameters of
signal entering an underwater receiver with isotropic directional diagram are calculated. It is shown that surface waves
strongly influence the temporal characteristics of signal at small depths of receiver location and in clear water. The
influence of geometrical factors, including the size of receiving aperture and the angular characteristics of emitter, is
studied. In the calculations, it is assumed that surface waves are isotropic, the elevation spectrum is determined by the
Pierson-Moskowitz formula, and the surface slope variance corresponds to the Cox and Munk data. As the Green
function of the radiative transfer equation we used the solution of this equation in the refined self-similar approximation
taking into account diffusion of photons along multipaths. This method is generalized in the same approximations to
evaluate the temporal characteristics of lidar signals reflected from the bottom or water. Delay and broadening of pulse
echo signal for two types of lidars, i.e., with isotropic and extremely narrow receiving diagrams, are calculated. The
contribution of waves to delay and broadening of echo signal in lidars is, as a rule, several times smaller than the
contribution of multiple scattering effects in water; nevertheless it should be taken into account for correct estimation of
the limiting depth resolution of lidar. It is shown that lidar with a narrow directional diagram has a better depth
resolution than lidar with a wide diagram. However for some sets of parameters in these lidars, the wave contribution to
signal delay can significantly exceed the contribution of water. The fulfilled estimates are greatly important for bathymetric lidars.
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