An example of absorption, scattering and attenuation spectra measured with a WET Labs ac-s. These measurements were carried out in the laboratory a culture of Chaetoceros rostratus. The spectrum labeled a_pg is the total absorption minus water. It is the sum of absorption by particulate and dissolved materials. It is measured using an unfiltered ac-s. Similarly the curve labeled c_pg is the total attenuation coefficient spectrum. The curve labeled a_g is the absorption spectrum due to dissolved materials only. It is measured by filtering the sample through a 0.2 mm filter. In the lower figure a_p is obtained by subtracting the a_g spectrum from the a_pg spectrum.

 

 

 

In the lower figure the curve labeled b_p is the scattering coefficient spectrum due to particulate materials only. It is obtained by subtracting the a_pg spectrum from the c_pg spectrum. It is implicitly assumed that dissolved materials do not scatter.

 

 

View photomicrographs of Chaetoceros rostratus.
(courtesy Dr. Jan Rines, University of Rhode Island).