<title>Backscatter anisotropy and the shape of retroreflected lidar pulse from sea water</title>

<title>Characteristics of light backscattering by seawater and lidar sounding of water column</title>

“…So the effect may be observed in the field for lidar sounding experiments within the upper layers of sea water nearby a river mouth 20 The opposite case, fi_() > /3, seems to be more frequent, at least for separate subsurface sea-water turbid layers 21,22 The unexpectedly high levels of echo-signals from separate depth, presented in the papers, are likely to be caused by the comparatively big values of /3(ir) at the corresponding horizons. Indeed, according to (16), the situation takes place if the first ("coherent') term in the integrand is the leading one, that is, if the horizon of the layer is not too deep (see (11) and Figure 1,c) and the receiver FOV is sufficiently narrow.…”

“…The point is that when a cw laser is used, the registered signal is the result of integration over all distances, 0 < z< oo (one has to substitute in (16) L, from (7) withf(t) = 1), and in view of comparatively slow descent of incoherent irradiences, E1 and E., P(t) c'ontains a significant "isotropic" part produced by the terms in (16) -O)=p()exp(-) + +fi, A<<c/2, Note that the size of receiver entrance pupil (that is, R0 in (7) for L , L ) was assumed to be "infinite"; for finite values of the parameter some additional signal descent with 0 is observed. With the assumptions formula (16) gives Let excitation pulse be 5-shaped, that is, f(t) = (t) in (4), (6), (7) and (11), and the receiver have infinite time-resolution, Rt) = (t). For further simplification we assume that in the range of significant depth values, that is…”

“…for L and Lj, as well as for corresponding spatial (R and Ri) and angular ( 9 and ) scales and radiant fluxes (l and 1, ), expressions (7) -(11) are still valid with R0 and U0 instead of R0 and Uo Let us take the following assumption on characteristic angular scale, O_ , of the variation of /3_(O) in the vicinity of U = . The angular width, 6 = U0 n , of the L -component of the radiance L, as well as the corresponding quantity, = n1 , for L , are supposed to be small compared with O_.…”