高頻雷達可應用於用於與海洋打撈、溢油響應、近岸區域管理，理解上層海洋動力等方面，目前全世界已有數百座高頻 (HF) 岸基雷達系統正在運作。目前，台灣海岸線安裝了二十五個高頻海岸雷達站，包括交叉/環路單極子和相控陣列雷達系統，主要用於觀測洋流。下一階段，二十一座相控陣列高頻（HF）和甚高頻 (VHF)雷達站將於2022年底建成，將被用於台灣近岸海域海浪之長期監測。為滿足高頻雷達應用軟體開發需求，本研究將聚焦於兩個高頻雷達應用議題，其一是評估不同海況下海表波浪參數反演結果之不確定性，其二是開發近岸船舶偵測算法。
首先都普勒頻譜模擬結果將被用於理解雷達截面積（RCS）與海況參數之理論關係。基於巴里克理論（Barrick’ s theory），高頻雷達截面積之都普勒頻譜可以從指定的方向波譜中模擬出來。方向波譜可由海浪譜計算得來，穩定風速（steady wind）可採用風波譜模型計算，季風或熱帶氣旋條件下可採用第三代海浪波譜模型計算。目前的初步結果為，已完成在不同風速、風向、雷達運行頻率、波譜分散度參數等狀況下都普勒頻譜模擬之敏感性測試。測試結果與文獻中譜型結果吻合良好，這表明我們的模擬軟體運行良好。
為從高頻雷達海洋回波估算波浪參數，如即示性波高、平均週期和海浪譜，研究採用已有方法來建立測試和評估方法表現之估算系統。最初，數值模擬被應用於評估不同天氣狀況下波浪參數之偏差。結果顯示，估算自都普勒頻譜之波浪參數，其不確定性在颱風條件下要低於季風條件。另外，為獲得來自實際運作之高頻雷達之波浪參數偏差，本研究採用頻率為27.75MHz接收後向散射訊號之高頻雷達系統（LERA MKIII）。該系統於2018年11月建於台灣臺中港北方，擁有4根發射天線及16根接收天線，是用於觀測海浪參數之高頻陣列雷達系統。
估算結果與位於雷達覆蓋區之聲波波流剖面儀（AWAC）實地觀測數據進行比對，比對結果顯示雷達系統運作良好，估算系統表現良好。此外，研究發現波浪關聯參數（connection coefficient of wave parameter）是存在的，此關聯參數是雷達徑向-波向夾角、微小參數（smallness parameter）以及譜寬參數（spectral width parameters）之函數。研究提出修正算法來估算比例因子（scaling factor），比例因子將被用於校驗（calibrate）雷達推算之波浪參數。結果顯示波高比例因子具有與雷達觀測方向-波向夾角之相依性，而波浪週期比例因子則主要受微小參數（smallness parameter）之影響。
本研究應用兩種方法從高頻雷達後向散射訊號偵測近岸海域船舶位置，即都普勒-距離（DR）方法與方位角-距離（AR）頻譜方法。船舶位置估算訊息已經與船舶自動偵測系統（AIS）提供之訊息比對驗證，結果顯示兩種方法均有良好估算效果。AR方法可以偵測船隻軌跡，RD方法可以提供這些目標物之雷達徑向速度。此外，我們也發現船舶長度、方向及航向等特征將影響目標物數量之偵測。整體上，本研究討論了將高頻雷達技術應用於海浪監測及船舶偵測之優點與限制。

Hundreds of high-frequency (HF) coastal radar systems are operated in the world for purposes related to marine salvage, oil spill response, coastal zone management, and understanding of upper ocean layer dynamics. At present, 25 HF coastal radar stations consisting of both cross/loop monopole and phased array systems were installed along Taiwan’s coastline and are primarily operated modes for observing ocean currents. In the next period, 21 phased array HF and very high-frequency (VHF) radar stations are on-going to install at the end of 2022 to monitor the evolution of ocean surface waves around the Taiwan island’s coastal area in the long term. In order to fulfill the demands for high-frequency radar application exploitation, this study focuses on two HF radar applications’ essential topics, which are assessing the uncertainty of ocean surface wave parameters under various sea-states and developing algorithms for coastal vessel monitoring.
First, the simulation of radar Doppler spectra was implemented to understand the theoretical relationship between radar cross-section (RCS) and sea-state parameters. Based on Barrick's theory, the Doppler spectra of HF radar cross-section are simulated from the given directional wave spectrum, which can be generated by applying the wind-wave spectra model for steady wind conditions or using the 3rd generation wave spectra model for monsoon and typhoon conditions. As preliminary results, various sensitivity tests of the simulated Doppler spectra are implemented under different wind speeds, wind directions, operating radar frequencies, and spreading parameters. The result showed that the simulated Doppler spectra agree well with those in the literature. This indicated that our simulation toolbox works well.
To estimate the wave parameters. i.e., significant wave height, mean period, and wave spectrum from HF radar sea-echoes, existing methods are implemented to establish estimators for testing and evaluating the method’s performance. In the beginning, the numerical simulation is used to assess the bias estimation of wave parameters under various weather conditions, such as the steady homogenous wind, monsoons, and typhoons. The results showed that the uncertainty of wave parameters estimated from simulated Doppler spectra under typhoon conditions is lower than those in monsoon conditions. In addition, to assess wave parameters’ bias from the actual HF radar data, the backscattered signal of the 27.75 MHz HF radar (LERA MKIII) system is used. This system consists of 16 Rx antennas in a linear array installed at the northern of the Taichung harbor, Taichung City, Taiwan, in late November 2018 for wave monitoring in the long term. Estimation results are compared with those of in-situ data observed by an acoustic wave and current profiles (AWAC) deployed in the radar’s footprint. The comparison results indicated that the radar system and estimators perform very well. Furthermore, it is found that the connection coefficients of wave parameters (which might be the function of radar-to-wave angle, smallness parameters, and spectral width parameters) have existed. Correction algorithms are proposed to estimate the scaling factor for calibrating radar-deduced wave parameters. The results demonstrated the dependence of wave height scaling factor on the radar-to-wave angle, while wave period scaling factors are mainly influenced by smallness parameters.
On the other hand, this study implements two approach methods to identify coastal vessel locations using HF radar backscattered signals: the rang-Doppler (RD) (or Doppler-Range, D-R) spectra and range-Angle brightness distribution methods. The estimated position of coastal vessels is compared with ship’s information from Automatic Identification System (AIS) data for assessing the performance of the radar system and the efficiency of detection methods. The results showed that both approaches work well. Furthermore, while the RA method can monitor ships’ trajectories, the RD approach can provide the radial speed of those targets. Besides, we also found the influence of the ship’s characteristics, including the length, the direction, and the heading, on the detection number of targets. Overall, this study illustrated the advantages and the limits of the HF radar technique for wave monitoring and ship detection.

[1] H. Roarty, T. Cook, L. Hazard, D. George, J. Harlan, S. Cosoli, L. Wyatt, E. Alvarez Fanjul, E. Terrill, M. Otero, J. Largier, S. Glenn, N. Ebuchi, B. Whitehouse, K. Bartlett, J. Mader, A. Rubio, L. Corgnati, C. Mantovani, A. Griffa, E. Reyes, P. Lorente, X. Flores-Vidal, K.J. Saavedra-Matta, P. Rogowski, S. Prukpitikul, S.-H. Lee, J.-W. Lai, C.-A. Guerin, J. Sanchez, B. Hansen, and S. Grilli, "The Global High Frequency Radar Network," Frontiers in Marine Science, vol. 6, 2019/05/14.
[2] S. Fujii, M. L. Heron, K. Kim, J. W. Lai, S. H. Lee, X. Wu, L.R. Wyatt, and W.C. Yang, "An overview of developments and applications of oceanographic radar networks in Asia and Oceania countries," Ocean Science Journal, vol. 48, 2013/03/01, pp. 69-97.
[3] A. Rubio, J. Mader, L. Corgnati, C. Mantovani, A. Griffa, A. Novellino, C. Quentin, L. Wyatt, J. S.-S., J. Horstmann, P. Lorente, E. Zambianchi, M. Hartnett, C. Fernandes, V. Zervakis, P. Gorringe, A. Melet, I. and Puillat, "HF Radar Activity in European Coastal Seas: Next Steps toward a Pan-European HF Radar Network," Frontiers in Marine Science, vol. 4, 2017/01/20, pp. 1-20.
[4] K. Hasselmann, "Determination of Ocean Wave Spectra from Doppler Radio Return from the Sea Surface," Nature Physical Science, vol. 229, 1971/01/01, pp. 16-17.
[5] D. Barrick, "First-order theory and analysis of MF/HF/VHF scatter from the sea," IEEE Transactions on Antennas and Propagation, vol. 20, 1972, pp. 2-10.
[6] D. Barrick, "Remote sensing of sea state by radar," in Ocean 72 - IEEE International Conference on Engineering in the Ocean Environment, 1972, pp. 186-192.
[7] D. D. Crombie, "Doppler Spectrum of Sea Echo at 13.56 Mc./s," Nature, vol. 175, 1955, pp. 681-682.
[8] E. W. Gill and J. Walsh, "High-frequency bistatic cross sections of the ocean surface," Radio Science, vol. 36, 2001, pp. 1459-1475.
[9] J. Walsh, R. Donnelly, and T. Stuart John, "A new technique for studying propagation and scattering for mixed paths with discontinuities," Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, vol. 412, 1987/07/08, pp. 125-167.
[10] J. Walsh, W. Huang, and E. Gill, "The First-Order High Frequency Radar Ocean Surface Cross Section for an Antenna on a Floating Platform," IEEE Transactions on Antennas and Propagation, vol. 58, 2010, pp. 2994-3003.
[11] R. L. Hardman, L. R. Wyatt, and C. C. Engleback, "Measuring the Directional Ocean Spectrum from Simulated Bistatic HF Radar Data," Remote Sensing, vol. 12, 2020, pp. 1-28.
[12] A. G. Voronovich and V. U. Zavorotny, "Measurement of Ocean Wave Directional Spectra Using Airborne HF/VHF Synthetic Aperture Radar: A Theoretical Evaluation," IEEE Transactions on Geoscience and Remote Sensing, vol. 55, 2017, pp. 3169-3176.
[13] F. Ding, C. Zhao, Z. Chen, and J. Li, "Sea Echoes for Airborne HF/VHF Radar: Mathematical Model and Simulation," Remote Sensing, vol. 12, 2020.
[14] D. E. Barrick, "Extraction of wave parameters from measured HF radar sea-echo Doppler spectra," Radio Science, vol. 12, 1977, pp. 415-424.
[15] Maresca J, J. W., and T. M. Georges, "Measuring rms wave height and the scalar ocean wave spectrum with HF skywave radar," Journal of Geophysical Research: Oceans, vol. 85, 1980/05/20, pp. 2759-2771.
[16] Z. Chen, C. Zezong, J. Yanni, F. Lingang, and Z. Gengfei, "Exploration and Validation of Wave-Height Measurement Using Multifrequency HF Radar," Journal of Atmospheric and Oceanic Technology, vol. 30, 2013/09/01, pp. 2189-2202.
[17] L. Wyatt, J. Venn, G. Burrows, A. Ponsford, M. Moorhead, and J. V. Heteren, "HF radar measurements of ocean wave parameters during NURWEC," IEEE Journal of Oceanic Engineering, vol. 11, 1986, pp. 219-234.
[18] H. C. Graber and M. L. Heron, "Wave height measurements from HF radar," Oceanography, vol. 10, 1997, pp. 90-92.
[19] B. K. Haus, L. K. Shay, P. A. Work, G. Voulgaris, R. J. Ramos, and J. Martinez-Pedraja, "Wind Speed Dependence of Single-Site Wave-Height Retrievals from High-Frequency Radars," Journal of Atmospheric and Oceanic Technology, vol. 27, 2010/08/01, pp. 1381-1394.
[20] L. Wyatt, "Significant waveheight measurement with h.f. radar," International Journal of Remote Sensing, vol. 9, 1988, pp. 1087-1095.
[21] A. Long and D. Trizna, "Mapping of North Atlantic winds by HF radar sea backscatter interpretation," IEEE Transactions on Antennas and Propagation, vol. 21, 1973, pp. 680-685.
[22] R. H. Stewart and J. R. Barnum, "Radio measurements of oceanic winds at long ranges: An evaluation," Radio Science, vol. 10, 1975, pp. 853-857.
[23] D. M. Fernandez, H. C Graber, J. Paduan, and D. Barrick, "Mapping Wind Directions with HF Radar," Oceanography, vol. 10, 1997, pp. 93-95.
[24] W. Huang, E. Gill, S. Wu, B. Wen, Z. Yang, and J. Hou, "Measuring Surface Wind Direction by Monostatic HF Ground-Wave Radar at the Eastern China Sea," IEEE Journal of Oceanic Engineering, vol. 29, 2004, pp. 1032-1037.
[25] L. R. Wyatt, "Shortwave Direction and Spreading Measured with HF Radar," Journal of Atmospheric and Oceanic Technology, vol. 29, 2012/02/01, pp. 286-299.
[26] E. W. Gill and J. Walsh, "Extraction of ocean wave parameters from HF backscatter received by a four-element array: analysis and application," IEEE Journal of Oceanic Engineering, vol. 17, 1992, pp. 376-386.
[27] R. Howell and J. Walsh, "Measurement of ocean wave spectra using narrow-beam HE radar," IEEE Journal of Oceanic Engineering, vol. 18, 1993, pp. 296-305.
[28] Y. Hisaki, "Nonlinear inversion of the integral equation to estimate ocean wave spectra from HF radar," Radio Science, vol. 31, 1996, pp. 25-39.
[29] L. R. Wyatt, "A relaxation method for integral inversion applied to HF radar measurement of the ocean wave directional spectrum," International Journal of Remote Sensing, vol. 11, 1990/08/01, pp. 1481-1494.
[30] N. Hashimoto and M. Tokuda, "A Bayesian Approach for Estimation of Directional Wave Spectra with HF Radar," Coastal Engineering Journal, vol. 41, 1999/06/01, pp. 137-149.
[31] Lukijanto, N. Hashimoto, and M. Yamashiro, "An improvement of modified Bayesian method for estimating directional wave spectra from HF radar backscatter," in Asian and Pacific Coasts 2009, ed: World Scientific Publishing Company, 2009, pp. 105-111.
[32] R. L. Hardman and L. R. Wyatt, "Inversion of HF Radar Doppler Spectra Using a Neural Network," Journal of Marine Science and Engineering, vol. 7, 2019, pp. 1-18.
[33] R. Shahidi and E. W. Gill, "A New Automatic Nonlinear Optimization-Based Method for Directional Ocean Wave Spectrum Extraction From Monostatic HF-Radar Data," IEEE Journal of Oceanic Engineering, vol. 46, 2021, pp. 900-918.
[34] A. L. Dzvonkovskaya and H. Rohling, "Target Detection with Adaptive Power Regression Thresholding for HF Radar," in 2006 CIE International Conference on Radar, 2006, pp. 1-4.
[35] A. L. Dzvonkovskaya and H. Rohling, "HF radar ship detection and tracking using WERA system," in 2007 IET International Conference on Radar Systems, 2007, pp. 1-5.
[36] F. Jangal, S. Saillant, and M. Helier, "Wavelet Contribution to Remote Sensing of the Sea and Target Detection for a High-Frequency Surface Wave Radar," IEEE Geoscience and Remote Sensing Letters, vol. 5, 2008, pp. 552-556.
[37] P. P. Gandhi and S. A. Kassam, "Analysis of CFAR processors in nonhomogeneous background," IEEE Transactions on Aerospace and Electronic Systems, vol. 24, 1988, pp. 427-445.
[38] H. Rohling, "Radar CFAR Thresholding in Clutter and Multiple Target Situations," IEEE Transactions on Aerospace and Electronic Systems, vol. AES-19, 1983, pp. 608-621.
[39] M. D. E. Turley, "Hybrid CFAR techniques for HF radar," in Radar 97 (Conf. Publ. No. 449), 1997, pp. 36-40.
[40] S. Grosdidier and A. Baussard, "Ship detection based on morphological component analysis of high-frequency surface wave radar images," IET Radar Sonar Navigation, vol. 6, 2012, pp. 813–821.
[41] L. Z. H. Chuang, Y. J. Chung, and S. T. Tang, "A Simple Ship Echo Identification Procedure With SeaSonde HF Radar," IEEE Geoscience and Remote Sensing Letters, vol. 12, 2015, pp. 2491-2495.
[42] S. Park, C. J. Cho, B. Ku, S. Lee, and H. Ko, "Simulation and Ship Detection Using Surface Radial Current Observing Compact HF Radar," IEEE Journal of Oceanic Engineering, vol. 42, 2017, pp. 544-555.
[43] C. Wang, B. Wen, and W. Huang "A Support Vector Regression-Based Method for Target Direction of Arrival Estimation From HF Radar Data," IEEE Geoscience and Remote Sensing Letters, vol. 15, 2018, pp. 674-678.
[44] W. Sun, W. Huang, Y. Ji, Y. Dai, P. Ren, P. Zhou, X. Hao, "A Vessel Azimuth and Course Joint Re-Estimation Method for Compact HFSWR," IEEE Transactions on Geoscience and Remote Sensing, vol. 58, 2020, pp. 1041-1051.
[45] G. Vivone, P. Braca, and J. Horstmann, "Knowledge-Based Multitarget Ship Tracking for HF Surface Wave Radar Systems," IEEE Transactions on Geoscience and Remote Sensing, vol. 53, 2015, pp. 3931-3949.
[46] J. S. Chen, D. T. Dao, and H. Chien, "Ship Echo Identification Based on Norm-Constrained Adaptive Beamforming for an Arrayed High-Frequency Coastal Radar," IEEE Transactions on Geoscience and Remote Sensing, vol. PP, 06/19 2020, pp. 1-11.
[47] M. Parker, Digital Signal Processing 101, Second Edition: Everything You Need to Know to Get Started: Newnes, 2017.
[48] W. Huang, X. Wu, B. Lund, and K. El-Darymli, "Advances in Coastal HF and Microwave (S- or X-Band) Radars," International Journal of Antennas and Propagation, vol. 2017, 2017/02/28.
[49] D. Crombie, "Resonant backscatter from the sea and its application to physical oceanography," in Ocean 72 - IEEE International Conference on Engineering in the Ocean Environment, 1972, pp. 174-179.
[50] T. Hilmer, "Radar Sensing of ocean wave heights," Master, University of Hawaii at Manoa, 2010.
[51] S. O. Rice, "Reflection of electromagnetic waves from slightly rough surfaces," Communications on Pure and Applied Mathematics, vol. 4, 1951/08/01, pp. 351-378.
[52] E. W. Gill, "The Scattering of High Frequency Electromagnetic Radiation from the Ocean Surface: An Analysis Based on a Bistatic Ground Wave Radar Configuration," PhD, Memorial University of Newfoundland, 1999.
[53] http://radarhf.ismar.cnr.it/HFRadarTech.html.
[54] M. Longuet-Higgins, D. E. Cartwright, and N. D. Smith, "Observations of the directional spectrum of sea waves using the motions of a floating buoy," in Ocean Wave Spectra, proceedings of a conference, Easton, Maryland, 1963, pp. 111-136.
[55] B. J. Lipa and D. E. Barrick, "Analysis methods for narrow-beam high-frequency radar sea echo," Technical Report, 1982.
[56] B. J. Lipa and D. E. Barrick, "Extraction of sea state from HF radar sea echo: Mathematical theory and modeling," Radio Science, vol. 21, 1986, pp. 81-100.
[57] D. E. Barrick and B. L. Weber, "On the Nonlinear Theory for Gravity Waves on the Ocean's Surface. Part II: Interpretation and Applications," Journal of Physical Oceanography, vol. 7, 1977, pp. 11-21.
[58] B. J. Lipa and B. Nyden, "Directional wave information from the SeaSonde," IEEE Journal of Oceanic Engineering, vol. 30, 2005, pp. 221-231.
[59] L. R. Wyatt, "High order nonlinearities in HF radar backscatter from the ocean surface," IEE Proceedings - Radar, Sonar and Navigation, vol. 142, 1995, pp. 293-300.
[60] W. J. Pierson and L. Moskowitz, "A proposed spectral form for fully developed wind seas based on the similarity theory of S. A. Kitaigorodskii," Journal of Geophysical Research (1896-1977), vol. 69, 1964/12/15, pp. 5181-5190.
[61] K. Hasselmann, T. P. Barnett, E. Bouws, H. Carlson, D. E. Cartwright, K. Enke, et al., "Measurements of wind-wave growth and swell decay during the Joint North Sea Wave Project (JONSWAP)," 1973.
[62] H. Mitsuyasu, F. Tasai, T. Suhara, S. Mizuno, M. Ohkusu, T. Honda, K. Rikiishi, "Observations of the Directional Spectrum of Ocean WavesUsing a Cloverleaf Buoy," J. Physical Oceanogr., vol. 5, 1975/10/01, pp. 750-760.
[63] W. Shen, K.-W. Gurgel, G. Voulgaris, T. Schlick, and D. Stammer, "Wind-speed inversion from HF radar first-order backscatter signal," Ocean Dynamics, vol. 62, 2012/01/01, pp. 105-121.
[64] Z. Alattabi, D. Cahl, and G. Voulgaris, "Swell and Wind Wave Inversion Using a Single Very High Frequency (VHF) Radar," Journal of Atmospheric and Oceanic Technology, vol. 36, 04/02 2019, pp. 987–1013.
[65] B. Lipa and D. E. Barrick, "Extraction of sea state from HF radar sea echo: Mathematical theory and modeling," Radio Science, vol. 21, 1986, pp. 81-100.
[66] L. R. Wyatt, J. J. Green, and A. Middleditch, "HF radar data quality requirements for wave measurement," Coastal Engineering, vol. 58, 2011/04/01, pp. 327-336.
[67] Z. Chen, C. Zezong, J. Yanni, F. Lingang, and Z. Gengfei, "Exploration and Validation of Wave-Height Measurement Using Multifrequency HF Radar," J. Atmos. Ocean. Technol., vol. 30, 2013/09/01, pp. 2189-2202.
[68] S. Heron and M. Heron, "A Comparison of Algorithms for Extracting Significant Wave Height from HF Radar Ocean Backscatter Spectra," Journal of Atmospheric and Oceanic Technology, vol. 15, 1998, pp. 1157-1163.
[69] M. L. Heron, P. E. Dexter, and B. T. McGann, "Parameters of the air-sea interface by high-frequency ground-wave Doppler radar," Marine and Freshwater Research, vol. 36, 1985, pp. 655-670.
[70] L. Cai, S. Shang, G. Wei, Z. He, Y. Xie, K. Liu, T. Zhou, J. Chen, F. Zhang, Y. Li, "Assessment of Significant Wave Height in the Taiwan Strait Measured by a Single HF Radar System," Journal of Atmospheric and Oceanic Technology, vol. 36, 2019, pp. 1419-1432.
[71] R. J. Ramos, H. C. Graber, and B. K. Haus, "Observation of Wave Energy Evolution in Coastal Areas Using HF Radar," Journal of Atmospheric and Oceanic Technology, vol. 26,01 Sep. 2009, pp. 1891-1909.
[72] G. Lopez, D. Conley, and D. Greaves, "Calibration, validation and analysis of an empirical algorithm for the retrieval of wave spectra from HF radar sea-echo," Journal of Atmospheric and Oceanic Technology, ol. 33, 2015, pp. 245-261.
[73] W. Mei and S.-P. Xie, "Intensification of landfalling typhoons over the northwest Pacific since the late 1970s," Nature Geoscience, vol. 9, 09/05/online 2016, pp. 753-757.
[74] L. H. Holthuijsen, M. D. Powell, and J. D. Pietrzak, "Wind and waves in extreme hurricanes," Journal of Geophysical Research: Oceans, vol. 117, 2012, pp. 1-15.
[75] A. Soloviev, R. Lukas, M. A. Donelan, and I. Ginis, "The Air-Sea Interface and Surface Stress under Tropical Cyclones," Scientific Reports, vol. 4, 2013, pp. 1-6.
[76] S. S. Chen, W. Zhao, M. A. Donelan, and H. L. Tolman, "Directional Wind–Wave Coupling in Fully Coupled Atmosphere–Wave–Ocean Models: Results from CBLAST-Hurricane," Journal of the Atmospheric Sciences, vol. 70, 2013/10/01, pp. 3198-3215.
[77] F. Ardhuin, A. Roland, F. Dumas, A.-C. Bennis, A. Sentchev, P. Forget, J. Wolf, F. Girard, P. Osuna, M. Benoit, "Numerical Wave Modeling in Conditions with Strong Currents: Dissipation, Refraction, and Relative Wind," Journal of Physical Oceanography, vol. 42, 2012/12/01, pp. 2101-2120.
[78] F. Ardhuin, S. T. Gille, D. Menemenlis, C. B. Rocha, N. Rascle, B. Chapron, J. Gula, J. Molemaker, "Small-scale open ocean currents have large effects on wind wave heights," Journal of Geophysical Research: Oceans, vol. 122, 2017/06/01, pp. 4500-4517.
[79] W. B. Chen, L. Y. Lin, J. H. Jang, and C. H. Chang, "Simulation of Typhoon-Induced Storm Tides and Wind Waves for the Northeastern Coast of Taiwan Using a Tide–Surge–Wave Coupled Model," Water, vol. 9, 2017, pp. 1-24.
[80] J. Walsh, W. Huang, and E. Gill, "The second-order high frequency radar ocean surface cross section for an antenna on a floating platform," IEEE Transactions on Antennas and Propagation, vol. 60, 10/01 2012, pp. 4804-4813.
[81] R. Shahidi and E. Gill, "Time-Domain Motion Compensation of HF-Radar Doppler Spectra for an Antenna on a Moving Platform," 2019 IEEE/OES Twelfth Current, Waves and Turbulence Measurement (CWTM), 2019, pp. 1-4.
[82] S. J. Anderson, "Remote sensing applications of HF skywave radar: The Australian experience," Turkish Journal of Electrical Engineering and Computer Sciences, vol. 18, 05/01 2010, pp. 339-372.
[83] P. E. Dexter and S. Theodoridis, "Surface wind speed extraction from HF sky wave radar Doppler spectra," Radio Science, vol. 17, 1982/05/01, pp. 643-652.
[84] J. Parent, "A frequency averaging method to improve sea-state measurements with a HF skywave radar," IEEE Transactions on Antennas and Propagation, vol. 35, 1987, pp. 467-469.
[85] S. J. Anderson, "Target Classification , Recognition and Identification with HF Radar," RTO SET Symposium, Oslo, Norway, 2004, pp. 1-25.
[86] K. W. Gurgel, G. Antonischki, H. H. Essen, and T. Schlick, "Wellen Radar (WERA): a new ground-wave HF radar for ocean remote sensing," Coastal Engineering, vol. 37, 1999/08/01/, pp. 219-234.
[87] P. Flament, D. Harris, M. Flament, I. Q. Fernandez, M. Hlivak, and X. Flores, et al., "A Compact High Frequency Doppler Radio Scatterometer for Coastal Oceanography," Washington, DC, 2016.
[88] H. H. Essen, K. W. Gurgel, and T. Schlick, "Measurement of ocean wave height and direction by means of HF radar: An empirical approach," Deutsche Hydrografische Zeitschrift, vol. 51, 1999/12/01, pp. 369-383.
[89] K. Gurgel, H. Essen, and T. Schlick, "An Empirical Method to Derive Ocean Waves From Second-Order Bragg Scattering: Prospects and Limitations," IEEE Journal of Oceanic Engineering, vol. 31, 2006, pp. 804-811.
[90] S. Heron and M. L. Heron, "A Comparison of Algorithms for Extracting Significant Wave Height from HF Radar Ocean Backscatter Spectra," Journal of Atmospheric and Oceanic Technology - J ATMOS OCEAN TECHNOL, vol. 15, 10/01 1998.
[91] R. Shahidi and E. W. Gill, "Two New Methods for the Extraction of Significant Wave Heights From Received HF-Radar Time Series," IEEE Geoscience and Remote Sensing Letters, vol. 17, 2020, pp. 2070-2074.
[92] D. E. Barrick, M. W. Evans, and B. L. Weber, "Ocean Surface Currents Mapped by Radar," Science, vol. 198, 1977, pp. 138-144.
[93] B. Lipa and D. Barrick, "Least-squares methods for the extraction of surface currents from CODAR crossed-loop data: Application at ARSLOE," IEEE Journal of Oceanic Engineering, vol. 8, 1983, pp. 226-253.
[94] D. Barrick and B. Lipa, "Evolution of Bearing Determination in HF Current Mapping Radars," Oceanography, vol. 10, 1997, pp. 72-75.
[95] R. O. Schmidt, "Multiple Emitter Location and Signal Parameter Estimation," IEEE Transactions on Antennas and Propagation vol. 34, 1986, pp. 276-280.
[96] J. Capon, "High-resolution frequency-wavenumber spectrum analysis," Proceedings of the IEEE, vol. 57, 1969, pp. 1408-1418.
[97] T. Helzel, M. Kniephoff, and L. Petersen, "WERA: Remote ocean sensing for current, wave and wind direction," in 2006 IEEE US/EU Baltic International Symposium, 2006, pp. 1-8.
[98] S. N. Bhuiya, F. Islam, and M. Matin, "Analysis of Direction of Arrival Techniques Using Uniform Linear Array," International Journal of Computer Theory and Engineering, vol. 4, 2012, pp. 931-934.
[99] L. C. Godara, "Application of antenna arrays to mobile communications. II. Beam-forming and direction-of-arrival considerations," Proceedings of the IEEE, vol. 85, 1997, pp. 1195-1245.
[100] C. Teague, "Multifrequency HF radar observations of currents and current shears," IEEE Journal of Oceanic Engineering, vol. 11, 1986, pp. 258-269.
[101] A. R. Kirincich, T. de Paolo, and E. Terrill, "Improving HF Radar Estimates of Surface Currents Using Signal Quality Metrics, with Application to the MVCO High-Resolution Radar System," Journal of Atmospheric and Oceanic Technology, vol. 29, 2012/09/01, pp. 1377-1390.
[102] A. Randazzo, M. A. Abou-Khousa, M. Pastorino, and R. Zoughi, "Direction of Arrival Estimation Based on Support Vector Regression: Experimental Validation and Comparison With MUSIC," IEEE Antennas and Wireless Propagation Letters, vol. 6, 2007, pp. 379-382.
[103] H. Cox, R. Zeskind, and M. Owen, "Robust adaptive beamforming," IEEE Transactions on Acoustics, Speech, and Signal Processing, vol. 35, 1987, pp. 1365-1376.
[104] J. Li, P. Stoica, and Z. Wang, "On robust Capon beamforming and diagonal loading," IEEE Transactions on Signal Processing, vol. 51, 2003, pp. 1702-1715.
[105] C. Liu and G. Liao, "Robust Capon beamformer under norm constraint," Signal Processing, vol. 90, 2010/05/01, pp. 1573-1581.
[106] I. R. Young, "The determination of confidence limits associated with estimates of the spectral peak frequency," Ocean Engineering, vol. 22, 1995/10/01, pp. 669-686.
[107] I. R. Young and L. A. Verhagen, "The growth of fetch limited waves in water of finite depth. Part 1. Total energy and peak frequency," Coastal Engineering, vol. 29, 1996/12/01, pp. 47-78.
[108] B. Lipa, B. Nyden, D. S. Ullman, and E. Terrill, "SeaSonde Radial Velocities: Derivation and Internal Consistency," IEEE Journal of Oceanic Engineering, vol. 31, 2006, pp. 850-861.
[109] E. W. Gill, M. L. Khandekar, R. K. Howell, and J. Walsh, "Ocean Surface Wave Measurement Using a Steerable High-Frequency Narrow-Beam Ground Wave Radar," Journal of Atmospheric and Oceanic Technology, vol. 13, 01 Jun. 1996, pp. 703-713.
[110] N. Hashimoto, L. R. Wyatt, and S. Kojima, "Verification of a Bayesian Method for Estimating Directional Spectra from HF Radar Surface Backscatter," Coastal Engineering Journal, vol. 45, 2003/06/01, pp. 255-274.
[111] L. R. Wyatt, "Limits to the Inversion of HF Radar Backscatter for Ocean Wave Measurement," Journal of Atmospheric and Oceanic Technology, vol. 17, 01 Dec. 2000, pp. 1651-1666.
[112] L. R. Wyatt, "Measuring the ocean wave directional spectrum ‘First Five’ with HF radar," Ocean Dynamics, vol. 69, 2019/01/01, pp. 123-144.
[113] G. Lopez, D. C. Conley, and D. Greaves, "Calibration, Validation, and Analysis of an Empirical Algorithm for the Retrieval of Wave Spectra from HF Radar Sea Echo," Journal of Atmospheric and Oceanic Technology, vol. 33, 01 Feb. 2016, pp. 245-261.
[114] A. Kirincich, "Improved Detection of the First-Order Region for Direction-Finding HF Radars Using Image Processing Techniques," Journal of Atmospheric and Oceanic Technology, vol. 34, 2017/08/01, pp. 1679-1691.
[115] L. R. Wyatt, "An evaluation of wave parameters measured using a single HF radar system," Canadian Journal of Remote Sensing, vol. 28, 2002/01/01, pp. 205-218.
[116] Y. Hisaki, "Ocean wave parameters and spectrum estimated from single and dual high-frequency radar systems," Ocean Dynamics, vol. 66, 2016/09/01, pp. 1065-1085.
[117] L. Wyatt, B. W. Green, A. Middleditch, M. D. Moorhead, J. Howarth, M. Holt, et al., "Operational Wave, Current, and Wind Measurements With the Pisces HF Radar," IEEE Journal of Oceanic Engineering, vol. 31, 2006, pp. 819-834.
[118] L. Wyatt, J. Green, and A. Middleditch, "Signal Sampling Impacts on HF Radar Wave Measurement," Journal of Atmospheric and Oceanic Technology, vol. 26, 04/01 2009, pp. 793-805.
[119] G. Lopez and D. Conley, "Comparison of HF Radar Fields of Directional Wave Spectra Against In Situ Measurements at Multiple Locations," vol. 7(8), 08/14 2019, pp. 1-17.
[120] R. Gomez, T. Helzel, L. R. Wyatt, G. Lopez, D. Conley, N. Thomas, et al., "Estimation of wave parameters from HF radar using different methodologies and compared with wave buoy measurements at the Wave Hub," in OCEANS 2015 - Genova, 2015, pp. 1-9.
[121] A. Middleditch and S. Cosoli, "The Australian coastal ocean radar network: Temporal and spatial scales of HF radar wave data," in OCEANS 2016 - Shanghai, 2016, pp. 1-8.
[122] Z. Tian, Y. Tian, and B. Wen, "Quality Control of Compact High-Frequency Radar-Retrieved Wave Data," IEEE Transactions on Geoscience and Remote Sensing, vol. 59, 2021, pp. 929-939.
[123] F. T. Ulaby, D. G. Long, W. J. Blackwell, C. Elachi, A. K. Fung, C. S. Ruf, K. Sarabandi, H. A. Zebker, J. J. Zyl, Microwave Radar and Radiometric Remote Sensing: University of Michigan Press, 2014.
[124] C. V. K. Prasada Rao, "Spectral width parameter for wind-generated ocean waves," Proceedings of the Indian Academy of Sciences - Earth and Planetary Sciences, vol. 97, 1988/12/01, pp. 173-181.
[125] D. E. Barrick, "Theory of HF and VHF Propagation Across the Rough Sea, 2, Application to HF and VHF Propagation Above the Sea," Radio Science, vol. 6, 1971/05/01, pp. 527-533.
[126] J. S. Chen, J. W. Lai, H. Chien, C. Wang, C. Su, K. Lin, M. Chen, Y. Chu, "VHF Radar Observations of Sea Surface in the Northern Taiwan Strait," Journal of Atmospheric and Oceanic Technology, vol. 36, 2019, pp. 297-315.
[127] R. Khan, B. Gamberg, D. Power, J. Walsh, B. Dawe, W. Pearson, D. Millan, "Target detection and tracking with a high frequency ground wave radar," IEEE Journal of Oceanic Engineering, vol. 19, 1994, pp. 540-548.
[128] A. M. Ponsford and J. Wang, "A review of High Frequency Surface Wave Radar for detection and tracking of ships," Turkish Journal of Electrical Engineering and Computer Sciences, vol. 18, 05/01 2010, pp. 409-428.
[129] J. F. Vesecky and K. E. Laws, "Identifying ship echoes in CODAR HF radar data: A Kalman filtering approach," in OCEANS 2010 MTS/IEEE SEATTLE, 2010, pp. 1-8.
[130] K. Laws, J. Vesecky, and J. Paduan, "Predicting the capabilities of ship monitoring by HF radar in coastal regions," in OCEANS'11 MTS/IEEE KONA, 2011, pp. 1-5.
[131] A. L. Dzvonkovskaya, K. W. Gurgel, H. Rohling, and T. Schlick, "HF Radar WERA Application for Ship Detection and Tracking," European Journal of Navigation, vol. 7, 2010, pp. 18-25.
[132] M. G. Kendall, A. Stuart, and J. K. Ord, The advanced theory of statistics. London: Charles Griffin and Company Ltd, 1967.
[133] J. J. Jen, "A Study of CFAR Implementation Cost and Performance Tradeoffs in Heterogeneous Environments," Master, Faculty of California State Polytechnic, Pomona, 2011.
[134] F. Bass, I. Fuks, A. Kalmykov, I. Ostrovsky, and A. Rosenberg, "Very high frequency radiowave scattering by a disturbed sea surface Part I: Scattering from a slightly disturbed boundary," IEEE Transactions on Antennas and Propagation, vol. 16, 1968, pp. 554-559,
[135] 錢 樺, 楊文榮, 賴堅戊, 徐堂家, 林昆毅, 陶瑞全, et al., "整合AIS與海洋陣列雷達系統之航安應用評估," 2019.
[136] https://comarsystems.com/download/ais-3r-datasheet/?wpdmdl=3579&refresh=62aed339aff0a1655624505.
[137] J. S. Chen, P. Hoffmann, M. Zecha, and C. H. Hsieh, "Coherent radar imaging of mesosphere summer echoes: Influence of radar beam pattern and tilted structures on atmospheric echo center," Radio Science, vol. 43, 2008/02/01 2008, pp. 1-16.
[138] 錢樺, 陶瑞全, 蘇青和, and 許義宏, "高頻陣列雷達訊號辨識船舶演算法之應用," 港灣季刊, pp. 9-19, 2020.