Abstract. For understanding and forecasting of hydrodynamics in coastal regions, numerical models have served as an important tool for many years. In order to assess the model performance, we compared simulations to observational data of water temperature and salinity. Observations were available from FerryBox transects in the southern North Sea and, additionally, from a fixed platform of the MARNET network. More detailed analyses have been made at three different stations, located off the English eastern coast, at the Oyster Ground and in the German Bight.FerryBoxes installed on ships of opportunity (SoO) provide high-frequency surface measurements along selected tracks on a regular basis.The results of two operational hydrodynamic models have been evaluated for two different time periods: BSHcmod v4 (January 2009 to April 2012) and FOAM AMM7 NEMO (April 2011 to April 2012). While they adequately simulate temperature, both models underestimate salinity, especially near the coast in the southern North Sea. Statistical errors differ between the two models and between the measured parameters. The root mean square error (RMSE) of water temperatures amounts to 0.72 • C (BSHcmod v4) and 0.44 • C (AMM7), while for salinity the performance of BSHcmod is slightly better (0.68 compared to 1.1).The study results reveal weaknesses in both models, in terms of variability, absolute levels and limited spatial resolution. Simulation of the transition zone between the coasts and the open sea is still a demanding task for operational modelling. Thus, FerryBox data, combined with other observations with differing temporal and spatial scales, can serve as an invaluable tool not only for model evaluation, but also for model optimization by assimilation of such high-frequency observations.

Mantle peridotites from three 3 x 3 metre grids sampled at kilometer distances from one another in the ca. 497 Ma Leka Ophiolite Complex (LOC), Norway, are examined in order to investigate the chemical and isotopic nature of oceanic mantle domains at the cm- to km-scale. The lithology of each grid locality is predominantly harzburgite, but includes layers and lenses of dunite and pyroxenite. Major and lithophile trace element compositions indicate a history of prior melting at pressures at or slightly below the garnet stability field. The common presence of orthopyroxenite veins likely reflects infiltration of silicic melts associated with supra-subduction zone processes. Osmium isotopes and highly siderophile element (HSE) abundance data for cm-scale sampling of traverses from the pyroxenites into the harzburgites reveal that the formation of the veins had little effect on Os isotopic compositions, and Os, Ir, Ru and Re abundances in the harzburgites. Adjacent to one of the orthopyroxenite veins studied, however, Pt and Pd abundances appear to have been strongly modified by interactions with vein-forming melts or fluids at distances of as much as 4-6 cm from the pyroxenite-harzburgite contact. Leka harzburgites have initial γOs values (% deviation from a chondritic reference) that range from -4.7 to + 2.2 (6.9% variation), with individual uncertainties of ± 0.2 units. Averaged initial Os isotopic compositions for harzburgites from the three grid sites separated by as much as 6 km, by contrast, differ by only a maximum of 2.6%. Isotopic heterogeneity on the cm- to m-scale is, therefore, larger than km-scale heterogeneity, indicating that at least some of the Os isotopic heterogeneity commonly observed globally among mantle peridotites is the result of processes that acted on a local scale. The general uniformity of these isotopic compositions among the three grid sites suggests that the portion of the oceanic mantle sampled by the LOC was relatively homogenous at the km-scale with respect to the long-term Re/Os ratio. The long-term projected Re/Os for LOC harzburgites is similar to the average required for modern abyssal peridotites. This observation strengthens prior interpretations, based largely on data for abyssal peridotites, that the Os isotopic evolution of oceanic mantle is consistent with a long-term 187Re/188Os of ∼0.38. The present ∼3 to 4% difference between the Os isotopic composition of the modern oceanic mantle and estimates for primitive mantle suggests that at least ∼6% of the mass of the oceanic mantle has been removed from it in the form of Re-enriched, mafic oceanic crust. Despite the recycling of this crust back into the mantle, most of it has evidently not been mixed back into accessible portions of the upper oceanic peridotite mantle. Compared to composition estimates for the primitive mantle, the median HSE compositions for the three grid sites are moderately- to strongly-depleted in Pd and Re, consistent with the corresponding lithophile element evidence for 20-30% melt depletion. As with initial γOs values, most harzburgites from a given grid are characterized by greater variations in absolute and relative HSE abundances than the differences between the median abundances of the three grid sampling locales. This observation indicates that as with Os isotopes, the HSE abundance heterogeneity among the harzburgites most strongly reflects cm- to m-scale melting and remobilization effects. Except for Ru, median HSE abundances for grid harzburgites are similar to median abundances for abyssal peridotites. The ∼30% lower median Ru/Ir in the LOC compared to the median ratio for abyssal peridotites suggests that the abundance of Ru in the oceanic mantle may be more variable than generally thought.

Abstract. FerryBoxes installed on ships of opportunity (SoO) provide high-frequency surface biogeochemical measurements along selected tracks on a regular basis. Within the European FerryBox Community, several FerryBoxes are operated by different institutions. Here we present a comparison of model simulations applied to the North Sea with FerryBox temperature and salinity data from a transect along the southern North Sea and a more detailed analysis at three different positions located off the English East coast, at the Oyster Ground and in the German Bight. In addition to the FerryBox data, data from a Fixed Platform of the MARNET network are applied. Two operational hydrodynamic models have been evaluated for different time periods: results of BSHcmod v4 are analysed for 2009–2012, while simulations of FOAM AMM7 NEMO have been available from MyOcean data base for 2011 and 2012. The simulation of water temperatures is satisfying; however, limitations of the models exist, especially near the coast in the southern North Sea, where both models are underestimating salinity. Statistical errors differ between the models and the measured parameters, as the root mean square error (rmse) accounts for BSHcmod v4 to 0.92 K, for AMM7 only to 0.44 K. For salinity, BSHcmod is slightly better than AMM7 (0.98 and 1.1 psu, respectively). The study results reveal weaknesses of both models, in terms of variability, absolute levels and limited spatial resolution. In coastal areas, where the simulation of the transition zone between the coasts and the open ocean is still a demanding task for operational modelling, FerryBox data, combined with other observations with differing temporal and spatial scales serve as an invaluable tool for model evaluation and optimization. The optimization of hydrodynamical models with high frequency regional datasets, like the FerryBox data, is beneficial for their subsequent integration in ecosystem modelling.

SupplementFigure S1: Comparison of average annual rainfall erosivity from 1971 -2000 calculated from the evaluation simulation (CPS-eval) and with the historical projection simulations (CPS-hist). Each point in the scatter plot represents a grid point.Table S1: Comparison of past and future changes in rainfall erosivity reported in the literature and calculated here (data from the projection run unless stated otherwise). The values from the other studies were either given in the text or tables, estimated from figures or extracted from reported data (see description of methodology below). For ease of comparison, we give the changes per decade and always assume linear trends. Note that while the spatial extent always matches, the temporal coverage can differ due to data availability.

Abstract. Heavy rainfall is the main driver of soil erosion by water which is a threat to soil and water resources across the globe. As a consequence of climate change, precipitation – and especially extreme precipitation – is increasing in a warmer world, leading to an increase in rainfall erosivity. However, conventional global climate models struggle to represent extreme rain events and cannot provide precipitation data at the high spatio-temporal resolution that is needed for an accurate estimation of future rainfall erosivity. Convection-permitting simulations (CPS) on the other hand, provide high-resolution precipitation data and a better representation of extreme rain events, but they are mostly limited to relatively small spatial extents and short time periods. Here we present for the first time rainfall erosivity and soil erosion scenarios in a large modelling domain such as Central Europe based on high-resolution CPS climate data generated with COSMO-CLM. We calculate rainfall erosivity for the past (1971–2000), present (2001–2019), near future (2031–2060) and far future (2071–2100) and apply the new data set in the soil erosion model WaTEM/SEDEM for the Elbe River basin. Our results showed that future increases in rainfall erosivity in Central Europe can be up to 84 % in the river basins of Central Europe. These increases are much higher than previously estimated based on regression with mean annual precipitation. In consequence, soil erosion and sediment delivery in the Elbe River basin are also increasing strongly. Locally, changes in erosion rates can be as high as 120 %. We conclude that despite remaining limitations, convection-permitting simulations have an enormous and to date unexploited potential for climate impact studies on soil erosion. Thus, the soil erosion modelling community should follow closely the recent and future advances in climate modelling to take advantage of new CPS for climate impact studies.