Ocean forecasting for the German Bight: from regional to coastal scales

Abstract

Abstract. This paper describes recent developments based on advances in coastal ocean forecasting in the fields of numerical modeling, data assimilation, and observational array design, exemplified by the Coastal Observing System for the North and Arctic Seas (COSYNA). The region of interest is the North and Baltic seas, and most of the coastal examples are for the German Bight. Several pre-operational applications are presented to demonstrate the outcome of using the best available science in coastal ocean predictions. The applications address the nonlinear behavior of the coastal ocean, which for the studied region is manifested by the tidal distortion and generation of shallow-water tides. Led by the motivation to maximize the benefits of the observations, this study focuses on the integration of observations and modeling using advanced statistical methods. Coastal and regional ocean forecasting systems do not operate in isolation but are linked, either weakly by using forcing data or interactively using two-way nesting or unstructured-grid models. Therefore, the problems of downscaling and upscaling are addressed, along with a discussion of the potential influence of the information from coastal observatories or coastal forecasting systems on the regional models. One example of coupling coarse-resolution regional models with a fineresolution model interface in the area of straits connecting the North and Baltic seas using a two-way nesting method is presented. Illustrations from the assimilation of remote sensing, in situ and high-frequency (HF) radar data, the prediction of wind waves and storm surges, and possible applications to search and rescue operations are also presented. Concepts for seamless approaches to link coastal and regional forecasting systems are exemplified by the application of an unstructured-grid model for the Ems Estuary.

The Coastal Observing System for Northern and Arctic Seas (COSYNA)

“…In order to observe the vertical distribution of key variables and their temporal development, these observations were complemented by extended in situ mapping of the North Sea during several research cruises and glider surveys. In situ observations taken with Wadden Sea poles, FINO3 platform, MARNET stations and FerryBox are also used in modelling (Stanev et al, 2016).…”

“…One of the distinguishing features of COSYNA lies therefore in the integration of observational data into models in order to close the spatial and temporal gaps of the observations and to calculate energy or matter fluxes (Stanev at al., 2016). Model studies are also essential for identifying regions with high sensitivity or variability in certain quantities that warrant the deployment of measurement devices.…”

Seabirds as samplers of the marine environment – a case study of northern gannets

“…The advantage of COSYNA in this context will be the variety of measured variables as well as the three-dimensional measurements so that stratification can be assessed which would not be available from remote-sensing sources (Baschek et al, 2016). Furthermore, the generation of models may prove particularly valuable for analysing and possibly predicting the distribution of seabirds Stanev et al, 2016). Finally, information on the marine environment may also be generated through the study of foraging seabirds directly, as their distinct prey-search behaviours may also inform physical oceanographers on the location of physical features, especially small-scale features such as fronts (e.g.…”

“…Whereas early work was targeted towards establishing the distribution patterns of seabirds (e.g. Brown, 1986;Tasker et al, 1987), later studies concentrated on improving our understanding of the underlying factors, including habitat parameters, mainly hydrographic features measured synoptically at sea or by remote techniques, and food availability, assessed by detecting and possibly quantifying prey at sea (e.g. Hunt Jr. et al, 1998;Davoren et al, 2003;Jahncke et al, 2005).…”

Science in support of coastal ocean forecasting—part 1

“…Largescale ocean modeling, observational, and forecasting projects provide products which are available everywhere, but the relevance of those products in coastal regions is often found inadequate (De Mey and Proctor 2009). Because of the smaller-scale, higher-frequency, coupled coastal dynamical, and biogeochemical processes found in coastal regions, and because of the presence of the coastline, shelves, coastal rivers, and other unique elements, specific coastal modeling, observational, and forecasting strategies have to be designed, within a general paradigm of integration between large-scale, regional, and coastal ocean forecasting systems (e.g., Stanev et al 2016). Science has to be advanced to that end, as a community effort: this is what the Coastal Ocean and Shelf Seas Task Team (COSS-TT) aims to do within GODAE Ocean View (GOV, www.godae-oceanview.org), as illustrated in Kourafalou et al (2015a, b).…”