Upward scattering coefficients and diffuse absorption for the down-and up-welling streams are key factors for remote sensing of waters

and the interaction between biology and optics.They are also important parameters of underwater light fields.On the assumption that the radiance field has no internal light source

no inelastic scattering and the water surface was flat

we studied the effects of the zenith of incident

albedo and scattering coefficient on upward scattering coefficient

diffuse absorption coefficient for the downwelling and upwelling streams on condition that a scattering phase function was selected.The upward scattering coefficient showed an increase with the zenith of incident increasing

but the coefficient did not change along with the albedo and scattering coefficient just below water surface.With depth increasing

the profile of upward scattering coefficients gradually approached a constant

and the constant increased with albedo increasing.The profile of upward scattering coefficients strictly increased and then gradually approached a constant with depth increasing when the incidence was normal to the water surface.With further enhancement of zenith angle

the profile gradually increased

then decreased

hereafter kept invariable;while the invariant value increased with albedo increasing

but did not change with zenith angle of incident.The pro-files of diffuse absorption coefficients for downwelling streams gradually shifted from strictly increase and followed stability to the new trend which took on first increase and next decrease

then to a constant state.Given that scattering coefficient and albedo was the same

the diffuse absorption coefficients for downwelling streams of different incident zenith converged to stability gradually.The less the albedo was

the more rapid convergent rate was

the shallower the depth of approaching to asymptotic state was.The characteristics of diffuse absorption coefficient for upwelling streams were very similar to that of diffuse absorption coefficient for downwelling streams

the former was merely bigger than the latter

and the diffuse absorption coefficients for upwelling streams were the maximum among them.