{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,4]],"date-time":"2026-04-04T18:12:56Z","timestamp":1775326376610,"version":"3.50.1"},"reference-count":27,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2018,9,16]],"date-time":"2018-09-16T00:00:00Z","timestamp":1537056000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Key Laboratory of Intelligent Perception and Systems for High-Dimensional Information of Ministry of Education(Nanjing University of Science and Technology)","award":["201804"],"award-info":[{"award-number":["201804"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Land-based, high-frequency (HF) surface wave radar has the unique capability of monitoring coastal surface parameters, such as current, waves, and wind, up to 200 km off the coast. The Doppler spectrum of the backscattered radar signal is characterized by two strong peaks that are caused by the Bragg-resonant scattering from the ocean surface. The wavelength of Bragg resonant waves is exactly half the radio wavelength (grazing incidence), and these waves are located at the higher frequency part of the wave spectral distribution. When HF radar operates at higher frequencies, the resonant waves are relatively shorter waves, which are more sensitive to a change in wind direction, and they rapidly respond to local wind excitation and a change in wind direction. When the radar operates at lower frequencies, the corresponding resonant waves are relatively longer and take longer time to respond to a change in wind direction due to the progress of wave growth from short waves to long waves. For the wind inversion from HF radar backscatter signals, the accuracy of wind measurement is also relevant to radar frequency. In this paper, a pattern-fitting method for extracting wind direction by estimating the wave spreading parameter is presented, and a comparison of the pattern-fitting method and a conventional method is given as well, which concludes that the pattern-fitting method presents better results than the conventional method. In order to analyze the wind direction inversion from radar backscatter signals under different wind conditions and at different radar frequencies, two radar experiments accomplished in Norway and Italy are introduced, and the results of wind direction inversion are presented. In the two experiments, the radar worked at 27.68 MHz and 12 MHz, respectively, and the wind conditions at the sea surface were quite different. In the experiment in Norway, 67.4% of the wind records were higher than 5 m\/s, while, in the experiment in Italy, only 18.9% of the wind records were higher than 5 m\/s. All these factors affect the accuracy of wind direction inversion. The paper analyzes the radar data and draws a conclusion on the influencing factor of wind direction inversion.<\/jats:p>","DOI":"10.3390\/rs10091480","type":"journal-article","created":{"date-parts":[[2018,9,17]],"date-time":"2018-09-17T10:42:20Z","timestamp":1537180940000},"page":"1480","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Wind Direction Inversion from Narrow-Beam HF Radar Backscatter Signals in Low and High Wind Conditions at Different Radar Frequencies"],"prefix":"10.3390","volume":"10","author":[{"given":"Wei","family":"Shen","sequence":"first","affiliation":[{"name":"Key Laboratory of Intelligent Perception and Systems for High-Dimensional Information of Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China"},{"name":"School of Computer Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China"}]},{"given":"Klaus-Werner","family":"Gurgel","sequence":"additional","affiliation":[{"name":"Institute of Oceanography, Faculty of Mathematics, Informatics and Natural Science, University of Hamburg, D-20146 Hamburg, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2018,9,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1038\/175681a0","article-title":"Doppler spectrum of sea echo at 13.56 mcs","volume":"4459","author":"Crombie","year":"1955","journal-title":"Nature"},{"key":"ref_2","unstructured":"Long, A.E., and Trizna, D.B. (1972). Measurements and preliminary interpretation of hf radar Doppler spectra from the sea-echo of an atlantic storm. NRL Rep., 7456."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"853","DOI":"10.1029\/RS010i010p00853","article-title":"Radio measurements of oceanic winds at long ranges: An evaluation","volume":"10","author":"Stewart","year":"1975","journal-title":"Radio Sci."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Tyler, G.L., Teague, C.C., Stewart, R.H., Peterson, A.M., Munk, W.H., and Joy, J.W. (1974). Wave directional spectra from synthetic aperture observations of radio scatter. Deep Sea Res. Oceanogr. Abstr.","DOI":"10.1016\/0011-7471(74)90063-1"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"679","DOI":"10.1109\/LGRS.2018.2809558","article-title":"Wind-direction mapping with a modified wind spreading function by broad-beam high-frequency radar","volume":"15","author":"Zeng","year":"2018","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"509","DOI":"10.1098\/rsta.1985.0054","article-title":"Directional spectra of wind-generated waves","volume":"315","author":"Donelan","year":"1985","journal-title":"Phil. Trans. R. Soc. Lond."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"804","DOI":"10.1109\/JOE.2006.886225","article-title":"An empirical method to derive ocean waves from second-order Bragg scattering: Prospects and limitations","volume":"31","author":"Gurgel","year":"2006","journal-title":"IEEE J. Ocean. Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"346","DOI":"10.5589\/m02-030","article-title":"Applying a unified directional wave spectrum to the remote sensing of wind wave directional spreading","volume":"28","author":"Heron","year":"2002","journal-title":"Can. J. Remote Sens."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"385","DOI":"10.5589\/m02-031","article-title":"Wave height and wind direction from the hf coastal ocean surface radar","volume":"28","author":"Heron","year":"2002","journal-title":"Can. J. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1032","DOI":"10.1109\/JOE.2004.834175","article-title":"Measuring surface wind direction by monostatic HF ground-wave radar at the eastern China sea","volume":"29","author":"Huang","year":"2004","journal-title":"IEEE J. Ocean. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1109\/MAES.2018.8336816","article-title":"Extraction of wind direction from the hf hybrid sky-surface wave radar sea echoes","volume":"33","author":"Chu","year":"2018","journal-title":"IEEE Aerosp. Electron. Syst. Mag."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1007\/s10236-011-0465-9","article-title":"Wind-speed inversion from HF radar first-order backscatter signal","volume":"62","author":"Shen","year":"2012","journal-title":"Ocean. Dyn."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2001","DOI":"10.1175\/JTECH-D-16-0249.1","article-title":"Sea Surface Wind Correction Using HF Ocean Radar and Its Impact on Coastal Wave Prediction","volume":"34","author":"Hisaki","year":"2017","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"206","DOI":"10.4031\/MTSJ.47.4.22","article-title":"Toward real-time, remote observations of the coastal wind resource using high-frequency radar","volume":"47","author":"Kirincich","year":"2013","journal-title":"Mar. Technol. Soc. J."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1377","DOI":"10.1175\/JTECH-D-15-0242.1","article-title":"Remote Sensing of the Surface Wind Field over the Coastal Ocean via Direct Calibration of HF Radar Backscatter Power","volume":"33","author":"Kirincich","year":"2016","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Zeng, Y., Zhou, H., Roarty, H., and Wen, B. (2016). Wind Speed Inversion in High Frequency Radar Based on Neural Network. Int. J. Antennas Propag., 2016.","DOI":"10.1155\/2016\/2706521"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1049\/iet-rsn.2018.0044","article-title":"Significant wave height extraction using a low-frequency HFSWR system under low sea state","volume":"12","author":"Li","year":"2018","journal-title":"IET Radar Sonar Navig."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1175\/JTECH-D-16-0139.1","article-title":"Dependence of 25-MHz HF Radar Working Range on Near-Surface Conductivity, Sea State, and Tides","volume":"34","author":"Halverson","year":"2017","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"643","DOI":"10.1029\/RS017i003p00643","article-title":"Surface wind speed extraction from hf sky-wave radar doppler spectra","volume":"17","author":"Dexter","year":"1982","journal-title":"Radio Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1264","DOI":"10.1175\/1520-0485(1980)010<1264:DWSODJ>2.0.CO;2","article-title":"Directional wave spectra observing during jonswap 1973","volume":"10","author":"Hasselmann","year":"1980","journal-title":"J. Phys. Oceanogr."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1109\/TAP.1972.1140123","article-title":"First-order theory and analysis of mf\/hf\/vhf surface from the sea","volume":"20","author":"Barrick","year":"1972","journal-title":"IEEE Trans. Atennas Propag."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1499","DOI":"10.1029\/RS019i006p01499","article-title":"Simplified theory of first- and second-order scattering of hf radio waves from the sea","volume":"19","author":"Robson","year":"1984","journal-title":"Radio Sci."},{"key":"ref_23","first-page":"59","article-title":"Diffraction of the irregular sea due to breakwaters","volume":"15","author":"Nagai","year":"1972","journal-title":"Coast. Eng. Japan. JSCE"},{"key":"ref_24","unstructured":"Borgman, L.E. (1984). Directional spectrum estimation for the sxy gauges. Tech. Rep. Coast. Eng. Res. Center Vicksburg."},{"key":"ref_25","unstructured":"Longuet-Higgins, M.S., Cartwright, D.E., and Smith, N.D. (1963). Observations of the directional spectrum of sea waves using the motions of a floating buoy. Ocean Wave Spectra, Prentice-Hall Inc."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"750","DOI":"10.1175\/1520-0485(1975)005<0750:OOTDSO>2.0.CO;2","article-title":"Observations of the directional spectrum of ocean waves using a cloverleaf buoy","volume":"5","author":"Mitsuyasu","year":"1975","journal-title":"J. Phys. Oceanogr."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Chu, X.L., Zhang, J., Wang, S.Y., and Ji, Y. (2015, January 15\u201316). A Comparison of Algorithms for Extracting Wind Direction from the Monostatic HF Radar Sea Echoes. Proceedings of the 2015 International Conference on Electronic Science and Automation Control, Zhengzhou, China.","DOI":"10.2991\/esac-15.2015.29"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/9\/1480\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:20:51Z","timestamp":1760196051000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/9\/1480"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,9,16]]},"references-count":27,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2018,9]]}},"alternative-id":["rs10091480"],"URL":"https:\/\/doi.org\/10.3390\/rs10091480","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,9,16]]}}}