A simulation of the southern North Sea in comparison with measurements from the North Sea Project Part 2 Suspended Particulate Matter

We simulate the distribution of suspended particulate matter in the southern North Sea using a three-dimensional baroclinic shelf-sea model. Process studies with individual coastal sources show the transport of material across the southern North Sea and out into the Norwegian trench is sensitive to specific wind conditions and settling velocities, so that material which settles during the summer can be transported faster than a passive tracer if its flux is unidirectional. Results from model runs with a number of coastal sources and size classes are compared with CTD data from the North Sea Project, using multiple linear regression to estimate the source strengths. The agreement is best during the winter, with correlation coefficients greater than 0.7; this falls below 0.4 in the summer. We estimate the input from Holderness and the Wash to be 5.6 M tonnes/year, and from the East Anglian coast to be 2.1 M tonnes/year. Due to the limited resolution of the model and the observations, we find we are unable to estimate the input from the English Channel or the Rhine with any degree of certainty.