An Examination of the Feasibility of Linear Deterministic Sea Wave Prediction in Multidirectional Seas Using Wave Profiling Radar: Theory, Simulation, and Sea Trials

Abstract

For a number of maritime tasks there is a short time period, typically only a few tens of seconds, where a critical event occurs that defines a limiting wave height for the whole operation. Examples are the recovery of fixed and rotary winged aircraft, cargo transfers, final pipe mating in fluid transfer operations, and launch/ recovery of small craft. The recovery of a 30-t rescue submersible onto a mother ship in the North Atlantic Treaty Organization (NATO) Submarine Rescue System is a prime example. In such applications short-term deterministic sea wave prediction (DSWP) can play a vital role in extending the sea states under which the system can be safely deployed. DSWP also has great potential in conducting experimental sea wave research at full scale. This report explores the feasibility of using data from an experimental wave profiling radar in achieving DSWP. The report includes theory, simulation, and field testing. Two forms of DSWP are employed: a fixed point system based upon a restricted set of wave directions from which some success is obtained and the other a fully two-dimensional technique that requires further development. The main finding is that using wave profiling radar for DSWP offers promise but requires improvements both to the spatial reliability and the resolution of the wave profiling radar and to the temporal resolution of its sweep before the technique can be considered to be viable as a usable tool.

A Novel Successive Cancellation Method to Retrieve Sea Wave Components from Spatio-Temporal Remote Sensing Image Sequences

“…Many offshore operations like the tensioning of a tanker, cargo transfer, and helicopter landing demand a deterministic prediction of the sea surface field in real-time [8][9][10][11][12][13][14][15]. In [13], the accurate real-time prediction of the sea surface field at the position of an operation platform is completely dependent on the retrieved sea wave components from a measured area in the vicinity of the platform [9][10][11][12][13][14][15][16]. In our paper, the wave component denotes the individual sine or cosine waves, since the sea surface can be seen as the superposition of numerous sine or cosine wave.…”

“…A 4D Var assimilation method was proposed to predict the sea surface field in [28]. In [15], based on a multi-directional sea wave model, a method using the 2D DFT on the acquired radar image to predict the sea surface field at a desired location and time was proposed.…”

Predicting sea waves in the presence of pink noise

“…Feeding the observations from the latter into the model results in an estimate of the underlying signal that can then be verified against the low-noise sensor's observations. An alternative method is to construct a buoy that contains the noisy sensors, train the model as before and use the estimated signal to predict the motion of the low-noise sensor using the method described in [4]. The danger with placing both noisy sensors within the same device is that the noise may no longer be independent between the two.…”

“…Figure 7 shows the linear correlations achieved by each method between the predictions and the ship's sensor observations. As in [4] the quality varies over time, but in general the model has provided the better predictive quality. Figure 8 shows a period of truth from the low-noise sensor overlaid with the multiple predictions obtained from the moving-window method based on (top) the model's estimate of the signal and (bottom) the buoy's filtered observations.…”

“…In many applications this does not matter as only the amplitudes or the shape of the power spectrum are of interest. However, in our case we are interested in prediction and for this the correct estimation of the phase is vital [4].…”