A year-long assessment of wave measurements retrieved from an HF radar network in the Gulf of Naples (Tyrrhenian Sea, Western Mediterranean Sea)

Saviano, Simona; Kalampokis, Alkiviadis; Zambianchi, Enrico; Uttieri, Marco

doi:10.1080/1755876x.2019.1565853

Cited by 35 publications

(99 citation statements)

References 63 publications

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“…In general, the agreement between HF radars and buoy periods is difficult since the radar centroid period does not coincide either with buoys Tp or Tm [4]. Long and Saviano's works [26,37] compared Tc with Tm and Tp, demonstrating that Tc takes values between the two of them. Regarding wave direction, the method used by these radars, the direction-finding, is conditioned by the cardioid model [14] and by an accurate antenna pattern measurement [38].…”

Section: Wave Parameters Validation In Terms Of Radar Range Cellsmentioning

confidence: 99%

Quality Assessment and Practical Interpretation of the Wave Parameters Estimated by HF Radars in NW Spain

et al. 2020

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High-frequency (HF) radars are efficient tools for measuring vast areas and gathering ocean parameters in real-time. However, the accuracy of their wave estimates is under analysis. This paper presents a new methodology for analyzing and validating the wave data estimated by two CODAR SeaSonde radars located on the Galician coast (NW Spain). Approximately one and a half years of wave data (January, 2014-April, 2015 were obtained for ten range cells employing two different sampling times used by the radar software. The resulting data were screened by an updated method, and their abundance and quality were described for each radar range cell and different wave regime; the latter were defined using the spectral significant wave height (Hm0) and mean wave direction (Dm) estimated by two buoys and three SIMAR points (SImulación MARina in Spanish, from the wave reanalysis model by Puertos del Estado (PdE)). The correlation between the results and the particularities of the different sea states (broadband or bimodal), the wind and the operation of the devices are discussed. Most HF radar wave parameters' errors occur for waves from the NNE and higher than 6 m. The best agreement between the Vilán radar and the Vilano-Sisargas buoy wave data was obtained for the dominant wave regime (from the northwest) and the southwest wave regime. However, relevant contradictions regarding wave direction were detected. The possibilities of reducing the wave parameters' processing time by one hour and increasing the numbers of range cells of the radars have been validated.HF radar technology is based on the Doppler shift of the radar's wave backscatter after colliding with the ocean gravity waves [6]. While current parameters are extracted from the first-order peaks of the Doppler-spectrum, which are produced by ocean waves of length one half of the radar's length, and with direction either away or towards the radar, the complete wave directional spectrum is based on the second-order peaks, produced by the interaction between any pair of ocean waves normalized by the previous first-order spectra [7,8]. Several designs of HF radars have been developed for obtaining ocean waves' information [9][10][11][12], and the one used in this paper is a broad-beam direction finding of CODAR, whose basis for estimating the directional wave spectrum has been extensively explained [8,13,14]. The present model of these radars, the SeaSonde, can use electromagnetic waves of frequencies between 4.4-50 MHz, but in oceanography, the most typically used are 5, 12 and 25 MHz. One of the benefits of these radars is to have only one or two monopole antennas (for emitting and receiving) which facilitate the location and installation [15,16].However, HF radars have some limitations [17,18]; their work frequency determines a threshold of the ratio between the wave backscatter and the noise floor of the signal that limits the minimum wave height that can be measured by the radar, and determines also a maximum wave height that, when exceeded, ensures the second-ord...

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Section: Wave Parameters Validation In Terms Of Radar Range Cellsmentioning

confidence: 99%

Quality Assessment and Practical Interpretation of the Wave Parameters Estimated by HF Radars in NW Spain

et al. 2020

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“…The first-order echoes are typically used to retrieve surface currents, while second order ones are analyzed to reconstruct the wave field [4]. While the analysis of surface currents is well established and the retrieval of wave parameters is an emerging topic [6][7][8][9], the use of first-order peaks to measure wind direction is still poorly explored in the SeaSonde system, while in the literature some investigation on acquisition and validation using phased-array systems are available. The first numerical model to extract the wind direction from HFr backscatter was suggested by Long and Trizna [10].…”

Section: Introductionmentioning

confidence: 99%

Wind Direction Data from a Coastal HF Radar System in the Gulf of Naples (Central Mediterranean Sea)

et al. 2021

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Results on the accuracy of SeaSonde High Frequency (HF) radar wind direction measurements in the Gulf of Naples (Southern Tyrrhenian Sea, Central Mediterranean Sea) are here presented. The investigation was carried out for a winter period (2th February–6th March) and for one summer month (August) of the reference year 2009. HF radar measurements were compared with in situ recordings from a weather station and with model data, with the aim of resolving both small scale and large scale dynamics. The analysis of the overall performance of the HF radar system in the Gulf of Naples shows that the data are reliable when the wind speed exceeds a 5 m/s threshold. Despite such a limitation, this study confirms the potentialities of these systems as monitoring platforms in coastal areas and suggests further efforts towards their improvement.

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“…Among the tools able to retrieve spatial data, HF radar is a remote sensing technique that has the capability of providing a relatively large coverage with high temporal and spatial resolution. Nowadays, this technology plays an essential role in monitoring surface currents ( [1][2][3]), whereas the suitability of its wave products for different applications has only recently begun to be explored ( [4][5][6][7]).…”

Section: Introductionmentioning

confidence: 99%

Comparison of HF Radar Fields of Directional Wave Spectra Against In Situ Measurements at Multiple Locations

Lopez

Conley

2019

JMSE

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The coastal zone hosts a great number of activities that require knowledge of the spatial characteristics of the wave field, which in coastal seas can be highly heterogeneous. Information of this type can be obtained from HF radars, which offer attractive performance characteristics in terms of temporal and spatial resolution. This paper presents the validation of radar-derived fields of directional wave spectra. These were retrieved from measurements collected with an HF radar system specifically deployed for wave measurement, using an established inversion algorithm. Overall, the algorithm reported accurate estimates of directional spectra, whose main distinctive characteristic was that the spectral energy was typically spread over a slightly broader range of frequencies and directions than in their in situ-measured counterparts. Two errors commonly reported in previous studies, namely the overestimation of wave heights and noise related to short measurement periods, were not observed in our results. The maximum wave height recorded by two in situ devices differed by 30 cm on average from the radar-measured values, and with the exception of the wave spreading, the standard deviations of the radar wave parameters were between 3% and 20% of those obtained with the in situ datasets, indicating the two were similarly grouped around their means. At present, the main drawback of the method is the high quality signal required to perform the inversion. This is in part responsible for a reduced data return, which did not exceed 55% at any grid cell over the eight-month period studied here.

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A year-long assessment of wave measurements retrieved from an HF radar network in the Gulf of Naples (Tyrrhenian Sea, Western Mediterranean Sea)

Cited by 35 publications

References 63 publications

Quality Assessment and Practical Interpretation of the Wave Parameters Estimated by HF Radars in NW Spain

Quality Assessment and Practical Interpretation of the Wave Parameters Estimated by HF Radars in NW Spain

Wind Direction Data from a Coastal HF Radar System in the Gulf of Naples (Central Mediterranean Sea)

Comparison of HF Radar Fields of Directional Wave Spectra Against In Situ Measurements at Multiple Locations

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