Sequoia LISST-100X, Руководство пользователя

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LISST-100X User’s Guide 47

However, sediment particles in the aquatic
environment are never perfect spheres. Consequently
Sequoia provides an option to invert the scattering
pattern under the assumption that the particles are
randomly (or irregularly) shaped particles. The exact
details of how this inversion takes place is described
in a scientific paper by Agrawal et al.
7
, which can be
downloaded from the library section on Sequoia’s
website (
www.SequoiaSci.com ). The direct URL is
http://sequoiasci.com/library/technical.aspx?SectionNa
me=library
. The paper is also included on your ship
disk. A brief version of the method is described in this
News article on Sequoia’s website:
http://sequoiasci.com/Articles/ArticlePage.aspx?pageI
d=133
.

So what method should you use? If you are going to
compare with the output from another laser particle
sizer, for example a laboratory particle sizer, you
should choose the Spherical particle model. The
reason for this is that no other laser manufacturer
provides a randomly shaped particle model for
inversion, so there will be nothing to compare to.
Generally, it is recommended that you keep both
boxes checked (this is also the default option), so that
you won’t have to reprocess your data because you
need to see what the data look like when processed
as randomly shaped particles.

Please note that when you choose to process your
raw data files using the Random shaped particle
option, the size range of the processed data changes
according to Appendix B on page 101, although the
raw scattering data that are being processed are
exactly the same. For details, please consult the paper
by Agrawal et al.
5
4

Select Open Batch Processing from the File menu
Begins process of
specifying raw data
files and all
information needed
for batch data
processing.
5

Choose the serial number of the instrument that
collected the data to be processed.
Instrument serial
number selected.
7
Agrawal YC, Whitmire A, Mikkelsen OA, Pottsmith HC (2008): Light scattering by random shaped particles and
consequences on measuring suspended sediments by laser diffraction. Journal of Geophysical Research, Vol. 113,
C04023, doi:10.1029/2007JC004403.