The application of computational geometry to the analysis of directional wave spectra as measured by HF radar

1994 ◽  
Author(s):  
F.E. Isaac
Keyword(s):  
Computational Geometry ◽  
Hf Radar ◽  
Wave Spectra ◽  
Directional Wave

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

2019 ◽  
Vol 7 (8) ◽  
pp. 271 ◽  
Author(s):  
Guiomar Lopez ◽  
Daniel C. Conley
Keyword(s):  
Grid Cell ◽  
Hf Radar ◽  
Spectral Energy ◽  
Wave Spectra ◽  
Inversion Algorithm ◽  
Heterogeneous Information ◽  
Wave Heights ◽  
Directional Wave ◽  
Radar Wave

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.

scholarly journals VERIFICATION OF A MODIFIED BAYESIAN METHOD FOR ESTIMATING DIRECTIONAL WAVE SPECTRA FROM HF RADAR

2011 ◽  
Vol 1 (32) ◽  
pp. 65 ◽  
Author(s):  
Lukijanto Lukijanto ◽  
Noriaki Hashimoto ◽  
Masaru Yamashiro
Keyword(s):  
Field Data ◽  
Bayesian Method ◽  
Wave Spectrum ◽  
Coastal Engineering ◽  
Hf Radar ◽  
Ocean Wave ◽  
Wave Spectra ◽  
Directional Spectrum ◽  
Radio Science ◽  
Directional Wave

A Modified Bayesian Method (MBM) for estimating directional wave spectra from Doppler spectra obtained by HF radar is examined using field data which were employed in the verification of Bayesian Method (BM). Applicability, validity and accuracy of the MBM are demonstrated compared with the directional wave spectra estimated by BM and observed by buoy acquired from the reliable field data obtained from Surface Current and Wave Variability Experiments (SCAWVEX) project. The necessary conditions of the Doppler spectral components to be used to estimate a reliable directional spectrum are correspondingly estimated by BM. The results clearly demonstrate that directional wave spectra can be estimated by MBM on the basis of Doppler spectra. In addition, though BM shows very time consuming in computations, BM is more robust against the presence of noise than MBM. References Akaike, H. (1980). Likelihood and Bayesian procedure, Bayesian statistics. In J.M. Bernardo, M.H. De Groot, D.U. Lindley, and A.F.M. Smith (Eds.), 143-166. Valencia: University Press. PMid:6252024 Barrick, D. E. (1972a). First order theory and analysis of MF/HF/VHF scatter from sea. IEEE Trans., Antennas Propagation, 20, 2-10. http://dx.doi.org/10.1109/TAP.1972.1140123 Barrick, D. E. (1977). Extraction of wave parameters from measured HF radar sea-echo Doppler spectra. Radio Science, 12(3), 415–424. http://dx.doi.org/10.1029/RS012i003p00415 Crombie, D. (1955). Doppler spectrum of sea echo at 13.56Mc/s. Nature, 175, 681-682. http://dx.doi.org/10.1038/175681a0 Hashimoto, N. and Kobune, K. (1986). Estimation of directional spectra from the maximum entropy principle. Proceedings of 5th International Offshore Mechanics and Arctic Engineering Symposium, 1, 80-85. Hashimoto, N., Kobune, K., and Kameyama, Y. (1987). Estimation of directional spectrum using the Bayesian approach, and its application to field data analysis. Report of P.H.R.I., 26(5), 57-100. Hashimoto N., and Tokuda M., (1999): A Bayesian Method Approach for Estimation of Directional Wave Spectra with HF radar, Coastal Engineering Journal, vol. 41, 137-147. http://dx.doi.org/10.1142/S0578563499000097 Hashimoto, N., Wyatt, L and Kojima, S. (2003): Verification of Bayesian Method for Estimating Directional Spectra from HF Radar Surface. Coastal Engineering Journal, 45(2), 255-274. http://dx.doi.org/10.1142/S0578563403000725 Hashimoto, N., Lukijanto, and Yamashiro, M. (2008). Development of a practical method for estimating directional spectrum from HF radar backscatter. Annual Journal of Coastal Engineering (in Japanese), 55(1), 1451-1455. http://dx.doi.org/10.2208/proce1989.55.1451 Hisaki, Y. (1996). Nonlinear inversion of the integral equation to estimate ocean wave spectra from HF radar. Radio science, 31(1), 25-39. http://dx.doi.org/10.1029/95RS02439 Howell, R., and Walsh, J. (1993). Measurement of ocean wave spectra using a ship mounted HF radar. IEEE Journal of Oceanic Engineering, 18(3), 306-310. http://dx.doi.org/10.1109/JOE.1993.236369 Lipa, B. J. and Barrick, D.E. (1982) : Analysis Methods for Narrow-Beam High-Frequency Radar Sea Echo, NOAA Technical Report ERL 420-WPL 56, 1-55. Lukijanto, Hashimoto, N., and Yamashiro, M. (2009a). Further modification practical method for estimating directional wave spectrum by HF radar. Proc. of 19 th ISOPE, 898-905. Lukijanto, Hashimoto, N., and Yamashiro, M. (2009b). An improvement of Modified Bayesian Method for estimating directional wave spectra from HF radar backscatter. Proceedings of 5 th APAC (Asian and Pacific Coasts), 105-111. Lukijanto, Hashimoto, N., and Yamashiro, M. (2009c). A comparison of analysis methods for estimating directional wave spectrum from HF ocean radar. Journal of Memoirs of the Faculty of Engineering, 69(4). Kyushu University, 163-185. Wyatt, L.R. (1990). A relaxation method for integral inversion applied to HF radar measurement of the ocean wave directional spectrum. International Journal Remote Sensing, 11(8), 1481-1494. http://dx.doi.org/10.1080/01431169008955106 Wyatt, L. R. Gurgel, K.W., Peters, H.C., Prandle, D., Krogstad, H.E., Haug, O., Gerritsen, H., Wensink, G.J. (1997b). The SCAWVEX Project. Proceedings of WAVES97, ASCE.

Multi-peaked directional wave spectra based on extensive field measurement data in the Gulf of Oman

2021 ◽  
Vol 230 ◽  
pp. 109057
Author(s):  
Mohammad Adibzade ◽  
Mehdi Shafieefar ◽  
Hassan Akbari ◽  
Roozbeh Panahi
Keyword(s):  
Field Measurement ◽  
Measurement Data ◽  
Wave Spectra ◽  
Gulf Of Oman ◽  
Extensive Field ◽  
Directional Wave
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