Paleoenvironmental reconstruction of Triassic floras from the Central North Sea

The Triassic sediments of the Central North Sea (CNS) are considered to have been deposited in a continental environment under a semi-arid climate. The Skagerrak Formation in particular, comprises an alternation of sandstone and mudstone members, the development of which is considered to be climatically driven. However, conflicting models exist as to how climate influences member deposition. Here we analyse the climatic signal using a multivariate statistical approach in which de-trended correspondence analysis (DCA) is applied to palynological observations to quantify environmental reconstruction. Using DCA it has been possible to define paleoecological groups and construct a relative hydrological state trend showing hydrological conditions within the centre of the CNS basin during the Triassic. The resultant trends reveal that the relationship between hydrological conditions in the basin and the development of individual sandstones and mudstone members is perhaps not a simple as indicated by existing models. In particular our data suggest that whilst influenced by broader climate trends, in the basin centre, there is no simple relationship between climate change and sandstone/mudstone development. The data also indicates that the Julius and Jonathan mudstone members were deposited under differing hydrological conditions. The DCA trends shown here also suggest that the Carnian Pluvial Episode (CPE) documented from the South Permian Basin and Tethys is not expressed in the CNS.

An integrated marine data collection for the German Bight – Part 1: Subaqueous geomorphology and surface sedimentology (1996–2016)

The German Bight located within the central North Sea is a hydro- and morphodynamically highly complex system of estuaries, barrier islands, and part of the world's largest coherent tidal flats, the Wadden Sea. To identify and understand challenges faced by coastal stakeholders, such as harbor operators or governmental agencies, to maintain waterways and employ numerical models for further analyses, it is imperative to have a consistent database for both bathymetry and surface sedimentology. Current commercial and public data products are insufficient in spatial and temporal resolution and coverage for recent analysis methods. Thus, this first part of a two-part publication series of the German joint project EasyGSH-DB describes annual bathymetric digital terrain models at a 10 m gridded resolution for the German North Sea coast and German Bight from 1996 to 2016 (Sievers et al., 2020a, https://doi.org/10.48437/02.2020.K2.7000.0001), as well as surface sedimentological models of discretized cumulative grain size distribution functions for 1996, 2006, and 2016 on 100 m grids (Sievers et al., 2020b, https://doi.org/10.48437/02.2020.K2.7000.0005). Furthermore, basic morphodynamic and sedimentological processing analyses, such as the estimation of, for example, bathymetric stability or surface maps of sedimentological parameters, are provided (Sievers et al., 2020a, b, see respective download links).

Spectral shapes and parameters from three different wave sensors

The quality of wave measurements is of primary importance for the validation of wave forecasting models, satellite wave calibration and validation, wave physics, offshore operations and design and climate monitoring. Validation of global wave forecasts revealed significant regional differences, which were linked to the different wave buoy systems used by different countries. To fully understand the differences between the wave measurement systems, it is necessary to go beyond investigations of the integral wave parameters height, period and direction, into the frequency spectra and the four directional Fourier parameters that are used to estimate the directional distribution. We here analyse wave data measured from three different sensors (non-directional Datawell Waverider buoy, WaveRadar Rex, Optech laser) operating at the Ekofisk oil production platform located in the central North Sea over a period of several months, with significant wave height ranging from 1 to 10 m. In general, all three sensors provide similar measurements of the integral wave properties and frequency spectra, although there are some significant differences which could impact design and operations, forecast verification and climate monitoring. For example, the radar underestimates energy in frequency bands higher than 8 s by 3–5%, swell (12.5–16 s) by 5–13%, while the laser has 1–2% more energy than the Waverider in the most energetic bands. Lee effects of structures are also estimated. Lower energy at the frequency tail with the radar has an effect on wave periods (they are higher); wave steepness is seen to be reduced by 10% in the wind seas. Goda peakedness and the unidirectional Benjamin-Feir index are also examined for the three sensors.

An Integrated Marine Data Collection for the German Bight – Part I: Subaqueous Geomorphology and Surface Sedimentology

The German Bight located within the central North Sea is a hydro- and morphodynamically highly complex system of estuaries, barrier islands and part of the world’s largest coherent tidal flats, the Wadden Sea. To identify and understand challenges faced by coastal stakeholders, such as harbor operators or governmental agencies, to maintain waterways and employ numerical models for further analyses, it is imperative to have a consistent data base for both bathymetry and surface sedimentology. Current commercial and public data products are insufficient in spatial and temporal 15 resolution and coverage for recent analyses methods. Thus, this first part of a two-part publication series of the German joint project EasyGSH-DB describes annual bathymetric digital terrain models in a 10 m gridded resolution for the German North Sea coast and German Bight from 1996 to 2016 (Sievers et al., 2020a, https://doi.org/10.48437/02.2020.K2.7000.0001), as well as surface sedimentological models of discretized cumulative grain size distribution functions for 1996, 2006 and 2016 on 100 m grids (Sievers et al., 2020b, https://doi.org/10.48437/02.2020.K2.7000.0005). Furthermore, basic morphodynamic and sedimentological 20 processing analyses, such as the estimation of e.g. bathymetric stability or surface maps of sedimentological parameters, are provided (Sievers et al., 2020a, 2020b, see respective download links).