Weather and climate related spatial varability of high turbidity areas in the North Sea and the English Channel

Images from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite have been used to investigate the meteorological and climate induced variability of suspended particulate matter (SPM) concentration in the North Sea. The meteorology has been characterized by the 11 weather types deduced from a refined system of Lamb’s classification of synoptic weather charts. Climatological effects have been related to the North Atlantic Oscillation index. The surface SPM concentration maps from MODIS have been ensemble averaged according to these weather types or climatological conditions. The data show that each type has a distinct distribution of surface SPM concentration in the North Sea. The differences are explained by different hydrodynamic and wave conditions. The occurrence of storms will impact the shallow regions by increasing the resuspension of bottom material. Prevailing winds will, on the other hand, change the residual transport of SPM in the North Sea. The more protected Southern Bight exhibits relatively stronger influences of advection, whereas in the central North Sea and the German Bight resuspension is more pronounced. This patterns result in an alternation of relatively high SPM concentration in the Southern Bight and in the rest of the southern North Sea during certain weather conditions. Limitations in satellite images have been assigned to stratification effects due to the occurrence of highly concentrated mud suspensions during certain weather types. The approach provides a tool to improve our understanding of coastal and shelf sea processes, especially with respect to variations of SPM concentration distribution according to weather, climate and climate change.