Polar nephelometer for sea truth measurements.

Abstract

The SeaWiFS Pre-launch Science Working Group pointed out the importance of in situ measurements of the volume scattering function for sea water. Thus a need has arisen for the development of a new polar nephelometer which can support such measurements, because presently used instruments are not adequate to this task. We propose here a new approach to measure the volume scattering function, in which a light source and photodetector are fixed and angle deviation is implemented via rotation of a special periscope prism with three reflecting facets. The shape of this special periscope prism together with precisely adjusted dimensions allow the detection of the scattered radiance practically over the full angular range including the case of direct beam attenuation measurement. This approach gives us the opportunity to develop a fast and compact polar nephelometer, capable of measuring the volume scattering function over the full angular range using modem systems of data acquisition, managing and processing. 11 refs., 2 figs.