The quick estimates are based on weighted sum of the net scattered
light. One set of weight factors yields the total volume concentration;
the other yields the area concentration of particles. The volume/area
ratio provides mean diameter, also known as the Sauter Mean
Diameter (SMD). Notably, SMD can be quite different from D
50
in broad
or multi-modal size distribution situations. The SMD output is set to
zero in very clear waters, i.e. when transmission is above 98%. In such
clear waters, the SMD can become erratic. [For an explanation of this
method of SMD derivation, see: Shaped Focal Plane Detectors for
Particle Concentration and Mean Size Observations; Agrawal, Y.C. and
O.A. Mikkelsen, (2009), Optics Express, v 17, n 25, pp 23066-23077].
The multi-angle scattering can be interpreted via inversion as arising
from spherical particles, or from irregularly shaped particles. Provided
software gives you the choice and the resulting PSD files are named
differently to distinguish them. As to which particle model to use, we
suggest that when working with natural waters, use the irregularly
shaped model. Only in exceptional circumstances, the spherical model
is appropriate.
To Next Page
Loading...
Need help?
General
