The finite angular resolution of nephelometers causes systematic measurement error of the volume scattering function. For scattering angles <90° this error depends mainly on the angular resolution of the nephelometer. For scattering angles >90° the error also depends on the attenuation of light in seawater and the instrument size. For nephelometers with angular resolution of ~2°, in clean ocean waters the error may assume a negative value of the order of −20% at scattering angles smaller than ~5°, i.e., the scattering function may be underestimated. The error may then increase to as much as +15% at ~10°, i.e., the scattering function may be overestimated. For greater scattering angles the error decreases to a few percent until, in turbid coastal waters, it may reach a negative peak of the order of −3% at ~170°, followed by an increase to about +15% for scattering angles in the vicinity of 175°.
© 1990 Optical Society of America
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