Fachbeiträge

Sämtliche Fachbeiträge aus den Hydrographischen Nachrichten seit der Ausgabe HN 100 sind online verfügbar.
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Hydrographische Inhalte auf Stabkarten – Stabkarten zur Navigation im Seegebiet der Marshallinseln/Mikronesien im Pazifik

Insulaner der Marshallinseln/Mikronesien im Pazifik benutzten Gitterwerksignaturen auf Stabkarten als Orientierungshilfe zur Navigation. Exemplarisch werden zwei Stabkarten (Medos) mit Gitterwerksignaturen von charakteristischen Dünungswellen gezeigt. Knotenlinien oder okar werden durch Interferenzen von Dünungswellenablenkungen von Atollen und Inseln erzeugt. Durch die Approximation eines Atolls oder einer Insel in Form eines Wellenbrechers werden Interferenzmuster mathematisch durch die Theorie der Beugung/Diffraktion erklärt. Diese Charakteristiken von Wasserwellen können im 19. Jahrhundert als eine der ersten historischen Untersuchungsobjekte der Hydrographie betrachtet werden.

Marshallinseln | Stabkarte | Navigation | Diffraktion | Interferenz

Ausgabe: HN 108 Seite: 40–45
DOI: 10.23784/HN108-07
Autor/en: Ingo Hennings

Sea state from high-resolution satellite-borne SAR imagery

The Sea Sate Processor (SSP) was developed for fully automatic processing of high-resolution Synthetic Aperture Radar (SAR) data from TerraSAR-X (TS-X) satellites and implemented into the processing chain for Near Real Time (NRT) services in the DLR ground station »Neustrelitz«. The NRT chain was organised and tested to provide the processed data to the German Meteorological Service (DWD) in order to validate the new coastal forecast model CWAM (Coastal WAve Model) in the German Bight of the North Sea with 900 metre horizontal resolution. The NRT test-runs, wherein the processed TS-X data were transferred to DWD and then incorporated into forecast products reach the best performance about 10 minutes for delivery of processed TS-X data to DWD server after scene acquisition.

Remote sensing | Oceanography | Coastal processes | Sea state | NRT | Forecast

Ausgabe: HN 108 Seite: 34–38
DOI: 10.23784/HN108-06
Autor/en: Andrey Pleskachevsky, Stefan Wiehle, Sven Jacobsen, Claus Gebhardt, Björn Tings, Egbert Schwarz, Detmar Krause, Thomas Bruns, Jens Kieser

Satellite-derived bathymetry – An effective surveying tool for shallow-water bathymetry mapping

Unlike other survey methods satellite-derived bathymetry (SDB) offers a remote mapping of shallow water zones. It is based on the concept of using the reflectance intensity of different wavelengths (colours) of the sunlight which is recorded by the satellite sensor. This information in combination with relevant databases and physical models determines the shallow water depth down to the light penetration depth. In the last decade, there has been an increasing interest of SDB methods and derived data. Various exercises have been done by academia and industry to validate and evaluate SDB data sets (REF). This awareness is based on two major developments: the recent availability of very high-resolution satellite data mapping the seafloor in sufficient detail and the design of robust and standardised algorithms and workflows. The demand of accessing bathymetric data for the shallow water zone, costs and the ability to map with ship and airborne sensors have also led to high interest in this effective surveying tool. The zone is still poorly surveyed for various locations worldwide (IHO 2016a). This article provides an overview of all aspects of SDB surveys from satellite sources, SDB workflows and methods to use cases.

Satellite-derived bathymetry – SDB | Remote sensing | Earth observation | Mapping depth

Ausgabe: HN 108 Seite: 30–33
DOI: 10.23784/HN108-05
Autor/en: Knut Hartmann, Thomas Heege, Magnus Wettle, Marcus Bindel

The altimetry processing chain – Bathymetry for BASE-platform

The present article describes some of the most relevant features of the designed calculation chain for bathymetric products from satellite altimetry method that has been integrated into the BASE-platform service. We estimate bathymetry based on up-to-date data from Cryosat2 where the new generation of altimetry radar (SAR mode) is processed in-house by using analytical solutions for the retracking model. A new method is used for the de-noising of residual altimetry profiles. The solutions are calibrated with in-situ soundings to consider seafloor density variations.

BASE-platform | Altimetry | Bathymetry | Satellite altimeter | Gravity anomaly | Geoid

Ausgabe: HN 108 Seite: 24–28
DOI: 10.23784/HN108-04
Autor/en: Pau Gallés, Maite Muñoz, Bernat Martínez, Eduard Makhoul, María José Escorihuela, Mònica Roca

The BASE-platform project – Deriving the bathymetry from combined satellite data

The project »BAthymetry SErvice platform« (BASE-platform) addresses the lack of available up-to-date, high-resolution bathymetry data in many areas of the world. With the increasing number of earth observation satellites, e.g. by the ongoing deployment of ESA’s Sentinel fleet, remote sensing data of the oceans are widely available. Three sources of satellite information are combined in BASE-platform: optical, synthetic aperture radar (SAR) and altimetry data. BASEplatform’s ambition is to use these data for creating bathymetric maps and supply them to end users via a bathymetry data portal, where data will be available off-the-shelf as well as on demand. Adequate metadata will be provided along with the bathymetry so usability by the end user is ensured.

Remote sensing | Earth observation | Oceanography | Bathymetry | Data fusion

Ausgabe: HN 108 Seite: 20–23
DOI: 10.23784/HN108-03
Autor/en: Stefan Wiehle, Bernat Martínez, Knut Hartmann, Martin Verlaan, Tim Thornton, Simon Lewis, Dick Schaap