Towards Nonlinear Wave Reconstruction and Prediction From Synthetic Radar Images

2016 ◽  
Author(s):  
A. P. Wijaya
Keyword(s):  
Vertical Direction ◽  
Sea Surface ◽  
Sea State ◽  
Operational Effectiveness ◽  
State Reconstruction ◽  
Radar Images ◽  
First Results ◽  
Marine Radar ◽  
Offshore Activities

The use of remotely wave sensing by a marine radar is increasingly needed to provide wave information for the sake of safety and operational effectiveness in many offshore activities. Reconstruction of radar images needs to be carried out since radar images are a poor representation of the sea surface elevation: effects like shadowing and tilt determine the backscattered intensity of the images. In [1], the sea state reconstruction and wave propagation to the radar has been tackled successfully for synthetic radar images of linear seas, except for a scaling in the vertical direction. The determination of the significant wave height from the shadowed images only has been described in [2]. This paper will summarize these methods, and provides the first results for the extension to nonlinear seas.

scholarly journals Sea surface topography reconstruction from X-band radar images

2008 ◽  
Vol 19 ◽  
pp. 83-86 ◽  
Author(s):  
F. Serafino ◽  
C. Lugni ◽  
F. Soldovieri
Keyword(s):  
Sea Surface ◽  
State Monitoring ◽  
Sea State ◽  
Radar Images ◽  
Sea Surface Topography ◽  
X Band ◽  
Sea Current ◽  
Global Vision ◽  
Inversion Procedure

Abstract. The paper deals with the feasibility study of the sea state monitoring starting from X-band radar images. The exploitation of radar images allows to achieve a global vision of the sea state compared to the local vision given by the usual sensors as the buoys. The processing approach is based on the formulation of problem as an inverse one where starting from the electromagnetic field backscattered by the sea surface, the information about the sea state are retrieved. The reliability of the inversion procedure is shown by processing synthetic and experimental data where particular attention is focussed to the determination of the sea current and speed of the vessel.

Sea-State Monitoring Via X-Band Marine Radar Images Sequences: A New Approach for an Accurate Surface Currents Estimation

2009 ◽  
Author(s):  
Francesco Serafino ◽  
Claudio Lugni ◽  
Francesco Soldovieri
Keyword(s):  
Synthetic Data ◽  
Surface Current ◽  
Key Factors ◽  
State Monitoring ◽  
Sea State ◽  
Reconstruction Procedure ◽  
Factors Affecting ◽  
Radar Images ◽  
X Band ◽  
Marine Radar

This work deals with the sea state monitoring starting from marine radar images collected on a moving ship. For such a topic, one of the key factors affecting the reliability of the reconstruction procedure is the determination of the equivalent surface current that also accounts for the speed of the moving ship. Here, we propose a method able to evaluate also high values of the sea surface current. The reliability of the proposed procedure is shown by a numerical analysis with synthetic data. Finally, we present some preliminary results with measurements collected on a moving ship.

X-Band Radar as a Tool to Determine Spectral and Single Wave Properties

2006 ◽  
Author(s):  
Konstanze Reichert ◽  
Katrin Hessner ◽  
Jens Dannenberg ◽  
Ina Traenkmann
Keyword(s):  
Real Time ◽  
Ocean Waves ◽  
Sea Surface ◽  
Surface Elevation ◽  
Radar Signal ◽  
Sea State ◽  
Single Wave ◽  
Radar Images ◽  
X Band ◽  
Wave Properties

The Wave Monitoring System WaMoS II was developed for real time measurements of directional ocean waves spectra to monitor the sea state from fixed platforms in deep water or coastal areas as well as from moving vessels. The system is based on a standard marine X-Band radar used for navigation and ship traffic control. WaMoS II digitises the analogous radar signal and analyses the sea clutter information to obtain directional wave spectra from the sea surface in real time even under harsh weather conditions and during night. Spectral sea state parameters such as significant wave height, peak wave period and peak wave direction both for wind sea and swell are derived. Within the EU funded project ‘MaxWave’ and the German project ‘SinSee’ new algorithms were developed to determine sea surface elevation maps from radar images which are used to investigate the spatial and temporal evolution of single waves simultaneously. In this paper a short overview describes the calculation of surface elevation maps and the detection of individual waves. Considering two case studies, the results of spatial single wave detection and corresponding temporal single wave properties are compared and discussed. Individual wave parameters derived from radar images are compared to individual waves measured by a buoy. An application of the method to characterise extreme sea states is discussed.

Harmony's ocean elevation measurements: potential and performance

2020 ◽  
Author(s):  
Andreas Theodosiou ◽  
Paco Lopez Dekker ◽  
Marcel Kleinherenbrink ◽  
Gert Mulder
Keyword(s):  
Sea Surface ◽  
Surface Elevation ◽  
Sea State ◽  
Temporal Decorrelation ◽  
First Results ◽  
Sea State Bias ◽  
Sea Surface Heights ◽  
And Performance ◽  
Cross Track ◽  
Along Track

<p>Harmony, an Earth Explorer 10 candidate mission, consists of two receive-only Synthetic Aperture Radar (SAR) satellites using Sentinel-1D as the illuminator. The mission will switch between close formation phases and StereoSAR phases, dedicated to relative surface elevation and relative surface motion respectively. Interferometric observations of the ocean have, in the past, been hindered by the quick temporal decorrelation of the sea surface; a result of the along-track baseline that often comes with the cross-track baseline necessary for interferometry. Specialised SAR systems aiming to observe the oceans need to account for the decorrelation of the surface. SWOT overcomes the issue by fixing the two SAR antennas to physically eliminate their along-track separation. Due to the squinted, bistatic nature of the formation, Harmony can act as an altimeter, observing relative sea-surface heights (SSH) over unprecedented wide swaths. Hence, the mission promises to have highly coherent observations of the sea surface, leading to accurate surface elevation measurements. The wide swath will enable the recovery of mesoscale features of the ocean surface in a single pass. We will present the first results of the performance analysis of the mission's observations of elevation over the oceans. The effect of errors, namely the residual Doppler, baseline errors and sea-state bias, on the observations will also be discussed.</p>

scholarly journals Estimation of the Significant Wave Height from Marine Radar Images without External Reference

2019 ◽  
Vol 7 (12) ◽  
pp. 432 ◽  
Author(s):  
Ludeno ◽  
Serafino
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
State Monitoring ◽  
Sea State ◽  
Significant Wave ◽  
Radar Images ◽  
External Reference ◽  
Challenging Tasks ◽  
In Situ Sensors ◽  
Marine Radar

In the context of the sea state monitoring by means of the X-band marine radar, the estimation of a significant wave height (Hs) is, currently, one of the most challenging tasks. For its estimation, a calibration is usually required using an external reference, such as in situ sensors, and mainly buoys. In this paper, a method that allows us to avoid the need for an external reference for Hs estimation is presented. This strategy is, mainly, based on the correlation between a raw radar image and the corresponding non-calibrated wave elevation image to which varying its amplitude by using a scale factor creates a mathematical model for the radar imaging. The proposed strategy has been validated by considering a simulated waves field, generated at varying sea state conditions. The results show a good estimation of the significant wave height, confirmed by a squared correlation coefficient greater than 0.70 for each considered sea state.

Lifting Analysis of Subsea Framework Structures

2014 ◽  
Author(s):  
Tor E. Søfteland ◽  
Odd V. Skrunes ◽  
Daniel Karunakaran
Keyword(s):  
Structural Integrity ◽  
Maximum Load ◽  
Hydrodynamic Forces ◽  
Sea Surface ◽  
Hydrodynamic Coefficients ◽  
Splash Zone ◽  
Sea State ◽  
Dynamic Forces

Installation of subsea structures and equipment involves a lifting operation where the objects are exposed to large hydrodynamic forces when entering the oscillating sea-surface. During deployment, as the structure is lifted through the splash zone, snap forces due to slack or overload due to dynamic forces contribute to the maximum load experienced by the structure over the course of its design lifetime. This paper presents a method of how to verify the structural integrity of a subsea framework including determination of the maximum allowable sea-state in which the structure is safely installed. As well as describing an overall methodology for a subsea lifting analysis, hydrodynamic coefficients for cylinders in the splash zone is provided.

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