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The CODAR is a High-Frequency (HF) radar system. Recently, CODAR becomes widely used for monitoring ocean surface currents remotely in nearly real time. However, some environmental effects often hampers or weakens the strength of CODAR system, which would deteriorate the data quality of CODAR and result in missing data in the designated observation region. In this study, we analyzed complete CODAR...
The complex EOF analysis of ocean surface currents to the Lionrock is investigated using six days' currents data measured by OSMAR in the southwestern Taiwan Straits. The analysis shows that the first three EOF modes account for 89.51% of the variance and are judged to contain the only statistically significant results, and are the main modes. The analysis has also provided insight into the dynamics...
High frequency (HF) radar systems are useful for measuring the velocity of sea surface currents. Besides the ecological and economic importance of being able to accurately measure currents, the US Coast Guard uses HF radar to make decisions involved in search and rescue operations. Currently, 5 MHz or long-range HF radar systems output radial vector files that are calculated using a 180-minute averaging...
The proliferation of HF radar networks around the globe has made them a vital component of the ocean observing endeavor. There are approximately thirty-four nations with oceanographic HF radar networks, eight of which have over 10 radar stations in their network. Providing high quality measurements for sustained periods of time is of the utmost importance. The global HF radar network has been established...
Linear frequency-modulated continuous wave (LFMCW) is applied in continuous active sonar (CAS). Methods for echo detection and direct path interference (DPI) suppression are studied and evaluated by simulation and sea trial data. To detect the LFMCW echo, the received signal is first demodulated by the transmitting signal, resulting in a de-chirped signal, which is similar as in LFMCW radar. However,...
Mapping of surface currents using HF ocean radar has become a widely accepted technology in coastal industries and research, and for many long-term installations the data are being archived for open access. One aspect that has not been settled is the standards which are to be followed. This paper describes general standards for data accuracy, QA, QC and data archiving. Data from the Australian Ocean...
Ocean surface current data provided by shore-based High Frequency (HF) radar show sporadically non-realistic current vectors in some areas, particularly at the outer edges of the radar range. The present paper describes a quality control (QC) procedure which evaluates the data of an array-type HF radar system in near realtime and assigns a quality value on every single grid-cell measurement. The quality...
The periodogram and its variant, the Welch method, are two popular techniques used in spectral analysis. However, there has not been a thorough comparison of the estimation performances of these methods in current mapping by high frequency surface wave radar systems. Spectral leakage, frequency resolution, and variance are discussed in terms of the two applied techniques. The detection of a single-tone...
Wave induced motions limit the working time and safety of many offshore operations, e.g. crane lifts, LNG transfers, and helicopter landings. This paper details recent efforts to deterministically predict ocean surface waves using measurements from the WaMoS II. The WaMoS II derives full 3-dimensional sea surface elevation maps from nautical X-band radar images, yielding both sufficient resolution...
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