A comparison of surface current fields derived by beam forming and direction finding techniques as applied by the HF radar WERA

Gurgel, Klaus-Werner; Antonischki, G.; Schlick, T.

doi:10.1109/igarss.1997.609081

Cited by 11 publications

(4 citation statements)

References 4 publications

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“…Extensive validation exercises have proven the general reliability and provided accuracy estimates of both types of HFR systems over a wide variety of deployments [1]. With the exception of a limited number of test cases or cross-validation exercises [22][23][24][25][26][27][28], limited attempts have been made to compare vectors from different systems in overlapping areas. Even fewer attempts have been made to combine surface radial current data from different systems in their areas of common overlap, and assess the accuracy of the resulting current maps.…”

Section: Discussionmentioning

confidence: 99%

Interoperability of Direction-Finding and Beam-Forming High-Frequency Radar Systems: An Example from the Australian High-Frequency Ocean Radar Network

Cosoli

Vos

2019

Remote Sensing

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Direction-finding SeaSonde (4.463 MHz; 5.2625 MHz) and phased-array WEllen RAdar WERA (9.33 MHz; 13.5 MHz) High-frequency radar (HFR) systems are routinely operated in Australia for scientific research, operational modeling, coastal monitoring, fisheries, and other applications. Coverage of WERA and SeaSonde HFRs in Western Australia overlap. Comparisons with subsurface currents show that both HFR types agree well with current meter records. Correlation (R), root-mean-squares differences (RMSDs), and mean bias (bias) for hourly-averaged radial currents range between R = (−0.03, 0.78), RMSD = (9.2, 30.3) cm/s, and bias = (−5.2, 5.2) cm/s for WERAs; and R = (0.1, 0.76), RMSD = (17.4, 33.6) cm/s, bias = (0.03, 0.36) cm/s for SeaSonde HFRs. Pointing errors (θ) are in the range θ = (1°, 21°) for SeaSonde HFRs, and θ = (3°, 8°) for WERA HFRs. For WERA HFR current components, comparison metrics are RU = (−0.12, 0.86), RMSDU = (12.3, 15.7) cm/s, biasU = (−5.1, −0.5) cm/s; and, RV = (0.61, 0.86), RMSDV = (15.4, 21.1) cm/s, and biasV = (−0.5, 9.6) cm/s for the zonal (u) and the meridional (v) components. Magnitude and phase angle for the vector correlation are ρ = (0.58, 0.86), φ = (−10°, 28°). Good match was found in a direct comparison of SeaSonde and WERA HFR currents in their overlap (ρ = (0.19, 0.59), φ = (−4°, +54°)). Comparison metrics at the mooring slightly decrease when SeaSonde HFR radials are combined with WERA HFR: scalar (vector) correlations for RU, V, (ρ) are in the range RU = (−0.20, 0.83), RV = (0.39, 0.79), ρ = (0.47, 0.72). When directly compared over the same grid, however, vectors from WERA HFR radials and vectors from merged SeaSonde–WERA show RU (RV) exceeding 0.9 (0.7) within the HFR grid. Despite the intrinsic differences between the two types of radars used here, findings show that different HFR genres can be successfully merged, thus increasing current mapping capability of the existing HFR networks, and minimising operational downtime, however at a likely cost of slightly decreased data quality.

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Section: Discussionmentioning

confidence: 99%

Interoperability of Direction-Finding and Beam-Forming High-Frequency Radar Systems: An Example from the Australian High-Frequency Ocean Radar Network

Cosoli

Vos

2019

Remote Sensing

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“…phased array) [12]. DF technique uses some fitting algorithms, best-known is Multiple Signal Classification (MUSIC) [13], to find the incident angel matching the set of received sea echoes [14]. Meanwhile, in BF algorithm, the beam is steered to a desired direction through a phase shift between arrays.…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, in BF algorithm, the beam is steered to a desired direction through a phase shift between arrays. Therefore, this technique allows the HF radar to capture the whole echoes coming from the sea [14]. The HF Radar system commonly known for DF technique is CODAR SeaSonde and for BF is WERA [12], [14].…”

Section: Introductionmentioning

confidence: 99%

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Assessments of surface current variability along the mid-southern coast of Vietnam from high-frequency (HF) radar measurements

Trần¹,

Sentchev

Tran

et al. 2022

OCEANS 2022 - Chennai

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Characteristics of the coastal surface currents inVietnam are often challenging to be well-described due to the lack of reliable data. Thus, a remote sensing technology -highfrequency (HF) WavE RAdar (WERA) has been implemented to monitor the surface currents along the mid-southern coast of Vietnam, which is largely influenced by the strong South China Sea Western Boundary current system (SCSWBC). The HF radar data obtained from a measurement campaign in May, 2019 were checked for outliers through variance-filters. Thereafter, the velocity fields were reconstructed using 2DVar-EOF gap filling and interpolation method [1, 2] for further analysis. The reconstructed surface current maps showed that the main current direction in this area during summer was northeast and the flow was driven by the southwest monsoon which usually starts from May [3]. The eastern sector of the domain was noticed with remarkably strong northeast current. At the onset of summer monsoon, the jet was weaken and deviated, thus, strongly modified the dynamics of the region [4]. A current divergence was observed in the northeastern and eastern parts of the study area. Some other interesting features of surface circulation were revealed during the second week of measurements, on 9-10 of May. Those features are characteristics of the east Vietnam cyclonic eddy and the southeastward??? offshore current [3-5]. On May 9, the cyclonic eddy expanded further to the south and prevailed over the entire area within a week. Spectral analysis was performed to identify the dominant frequencies of the surface current variability. The results demonstrated the capability of HF radars in monitoring such sub-and meso-scale motions of near-shore surface currents.

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Remote Mapping of Sea Surface Currents Using HF Doppler Radar Networks

Joseph

2014

Measuring Ocean Currents

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A comparison of surface current fields derived by beam forming and direction finding techniques as applied by the HF radar WERA

Cited by 11 publications

References 4 publications

Interoperability of Direction-Finding and Beam-Forming High-Frequency Radar Systems: An Example from the Australian High-Frequency Ocean Radar Network

Interoperability of Direction-Finding and Beam-Forming High-Frequency Radar Systems: An Example from the Australian High-Frequency Ocean Radar Network

Assessments of surface current variability along the mid-southern coast of Vietnam from high-frequency (HF) radar measurements

Remote Mapping of Sea Surface Currents Using HF Doppler Radar Networks

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