Oceanic particle size distributions for the PacAtl and Arctic datasets

A dataset of nearly 400 measurements of the particle size distribution
(PSD) compiled from the Pacific, Atlantic, and Arctic Oceans is used to
examine variability in the magnitude and shape of the PSD, and to
characterize the partitioning of particle number, cross-sectional area,
and volume concentration among defined size intervals. The results
indicate that the relative contributions of three size classes based upon
the pico-, nano-, and microplankton size range exhibit substantial changes
among measures of particle size and between oceanic environments. The
single slope power law model commonly employed to characterize the PSD in
aquatic studies is demonstrated to have significant limitations in
capturing the complexity of PSD shapes observed for natural particle
assemblages, and in consequence poorly predicts the relative contributions
of these different size intervals. We show that specific percentile
diameters derived from the cumulative distributions of particle size are
strongly correlated with the contributions of these three size classes,
and that these non-parametric descriptors of the cumulative distribution
provide superior performance for estimating their contributions while
requiring no assumption of underlying PSD shape. A comparison of these
predictive relationships with independent field measurements suggests that
this approach is generally robust for particle assemblages representing a
wide diversity of marine environments.