Advantages of vertically adaptive coordinates in numerical models of stratified shelf seas

Gräwe, Ulf; Holtermann, Peter; Klingbeil, Knut; Burchard, Hans

doi:10.1016/j.ocemod.2015.05.008

Cited by 114 publications

(108 citation statements)

References 64 publications

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“…The atmospheric forcing was derived from the operational model of the German Weather Service with a spatial resolution of 7 km and a temporal resolution of 3 h. Input parameters were air temperature, humidity, cloud cover, air pressure, precipitation and wind fields Tudor and Williams (2004) for the determination of the likelihood that macro-litter items come from one of the five considered potential pollution sources taken at 10 m above mean sea level. In addition, data from a large scale model covering the North Sea/Baltic Sea was used to force the Western Baltic Sea model (Gräwe et al 2015b). Because of data availability, the model simulations covered the years 2003 to 2009, providing seven years of forcing for the particle-tracking tool.…”

Section: D-transport Modellingmentioning

confidence: 99%

Beach macro-litter monitoring on southern Baltic beaches: results, experiences and recommendations

et al. 2017

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Major objectives were to provide a comprehensive dataset on beach macro-litter for parts of the southern Baltic Sea and to analyse if the methodology is fully applicable and a suitable monitoring method in the Baltic. We carried out a regular macro litter beach monitoring (OSPAR methodology, 4 time a year) on 35 beaches along the German and Lithuanian Baltic coast over 2-5 years. Additional experiments addressed the subjectivity of the field surveys and spatio-temporal variability on different scales. We observed no seasonality of the data and a monthly compared to a 3-monthly sampling resulted in 3 times higher annual item numbers. Along the Lithuanian coast, the average number of items per survey varied between 138 and 340 and along the German Baltic coast between 7 and 404, with a median value of 47. All data showed a very high spatio-temporal variability. Using the Matrix Scoring Technique we assessed beach litter sources. With 50% tourism and recreation was the most important source. 3D-transport simulations helped to explain the minor role of shipping as a source and, compared to the North Sea, the low numbers of items on German Baltic beaches. Floating litter had a short duration time in the western Baltic Sea and offshore drift dominated. Further, the common regular beach cleanings reduced the potential for local litter accumulation and translocation. We suggest a monitoring system on 14 Baltic beaches in Germany and 2 in Lithuania and provide cost calculations. The analysis of macro-litter in cormorant nesting material and the search for beached dead animals did not show any result. We can conclude that the macro-litter beach monitoring method is less suitable for Baltic beaches and should only serve as a complementary method in combination with others.

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Section: D-transport Modellingmentioning

confidence: 99%

Beach macro-litter monitoring on southern Baltic beaches: results, experiences and recommendations

et al. 2017

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“…The application of the analytical solution to observed SPMC profiles requires information on corresponding k v values. These and energy dissipation rate and water density σ T were obtained from hydrodynamical simulations of Gräwe et al (2015), based on a 1 nmi numerical model of the North Sea and the Baltic Sea. In the vertical, 42 terrain-following levels were used.…”

Section: Data Processing and Sinking Velocity Extractionmentioning

confidence: 99%

Maximum sinking velocities of suspended particulate matter in a coastal transition zone

et al. 2016

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Abstract. Marine coastal ecosystem functioning is crucially linked to the transport and fate of suspended particulate matter (SPM). Transport of SPM is controlled by, amongst other factors, sinking velocity w s . Since the w s of cohesive SPM aggregates varies significantly with size and composition of the mineral and organic origin, w s exhibits large spatial variability along gradients of turbulence, SPM concentration (SPMC) and SPM composition. In this study, we retrieved w s for the German Bight, North Sea, by combining measured vertical turbidity profiles with simulation results for turbulent eddy diffusivity. We analyzed w s with respect to modeled prevailing dissipation rates and found that mean w s were significantly enhanced around log 10 ( (m 2 s −3 )) ≈ −5.5. This region is typically found at water depths of approximately 15 to 20 m along cross-shore transects. Across this zone, SPMC declines towards the offshore waters and a change in particle composition occurs. This characterizes a transition zone with potentially enhanced vertical fluxes. Our findings contribute to the conceptual understanding of nutrient cycling in the coastal region which is as follows. Previous studies identified an estuarine circulation. Its residual landward-oriented bottom currents are loaded with SPM, particularly within the transition zone. This retains and traps fine sediments and particulate-bound nutrients in coastal waters where organic components of SPM become remineralized. Residual surface currents transport dissolved nutrients offshore, where they are again consumed by phytoplankton. Algae excrete extracellular polymeric substances which are known to mediate mineral aggregation and thus sedimentation. This probably takes place particularly in the transition zone and completes the coastal nutrient cycle. The efficiency of the transition zone for retention is thus suggested as an important mechanism that underlies the often observed nutrient gradients towards the coast.

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“…Analysis of AMM15 will therefore focus on the period of GLOSEA forcing, allowing a 5 5 year spinup period prior to this date. For the eastern boundary, conditions have been taken from a regional Baltic simulation (Gräwe et al, 2015). This alternative data set was chosen due to the increased resolution (1/60…”

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AMM15: A new high resolution NEMO configuration for operational simulation of the European North West Shelf

Graham¹,

O’Dea²,

Holt³

et al. 2017

Preprint

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Abstract. This paper describes the next generation ocean forecast model for the European North West Shelf, which will become the basis of operational forecasts in 2018. This new system will provide a step change in resolution, and therefore our ability to represent small scale processes. The new model has a resolution of 1.5 km, compared with a grid spacing of 7 km in the current operational system. AMM15 (Atlantic Margin Model, 1.5 km) is introduced as a new regional configuration of NEMO v3.6. Here we describe the technical details behind this configuration, with modifications appropriate for the new high 5 resolution domain. Results from a 30 year non-assimilative run, using the AMM15 domain, demonstrate the ability of this model to represent the mean state and variability of the region.Overall, there is an improvement in the representation of the mean state across the region, suggesting similar improvements may be seen in the future operational system. However, the reduction in seasonal bias is greater off-shelf than on-shelf. In the North Sea, biases are largely unchanged. Since there has been no change to the vertical resolution or parameterisation 10 schemes, performance improvements are not expected in regions where stratification is dominated by vertical processes, rather than advection. This highlights the fact that increased horizontal resolution will not lead to domain-wide improvements. Further work is needed to target bias reduction across the North West Shelf region.

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Advantages of vertically adaptive coordinates in numerical models of stratified shelf seas

Cited by 114 publications

References 64 publications

Beach macro-litter monitoring on southern Baltic beaches: results, experiences and recommendations

Beach macro-litter monitoring on southern Baltic beaches: results, experiences and recommendations

Maximum sinking velocities of suspended particulate matter in a coastal transition zone

AMM15: A new high resolution NEMO configuration for operational simulation of the European North West Shelf

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