{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,5]],"date-time":"2025-11-05T14:31:45Z","timestamp":1762353105724,"version":"build-2065373602"},"reference-count":31,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2021,8,1]],"date-time":"2021-08-01T00:00:00Z","timestamp":1627776000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003711","name":"Ministry of Science and Technology","doi-asserted-by":"publisher","award":["MOST 109-2811-M-019-011"],"award-info":[{"award-number":["MOST 109-2811-M-019-011"]}],"id":[{"id":"10.13039\/501100003711","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Sea surface currents observed by high-frequency (HF) radars have been widely used in ocean circulation research. In this study, hourly sea surface currents observed by the Taiwan Coastal Ocean Dynamics Applications Radar (CODAR) system from 2015 to 2019 were analyzed by the empirical orthogonal function (EOF) analysis to reveal the characteristics of the sea surface currents around Taiwan Island. The study area is divided into two regions, the Kuroshio region east of Taiwan Island and the Taiwan Strait west of Taiwan Island. In the Kuroshio region, the first EOF mode shows that the Kuroshio is characterized by higher current speeds with greater variability in summer. The second and third EOF modes present a dipole eddy pair and single eddy impingement on the Kuroshio during different periods. The seasonal variation of the dipole eddy pair indicates that the cyclonic\/anticyclonic eddy on the north\/south side appears more frequently in summer. Single eddy impingement occurs at multiple periods, including daily, intraseasonal, interseasonal, and annual periods. For the Taiwan Strait, the first EOF mode displays the tide signals. The tides enter the Taiwan Strait from the north and south, forming strong sea surface currents around the northern tip of Taiwan Island and the Penghu Archipelago. The second EOF mode exhibits the seasonal changes of the sea surface currents driven by the monsoon winds. The sea surface currents in the northern Taiwan Strait are relatively strong, possibly due to the narrow and shallow terrain there. The high spatiotemporal resolution of sea surface currents derived from CODAR observations provide more detailed characteristics of sea surface circulation around Taiwan Island.<\/jats:p>","DOI":"10.3390\/rs13153025","type":"journal-article","created":{"date-parts":[[2021,8,1]],"date-time":"2021-08-01T21:44:32Z","timestamp":1627854272000},"page":"3025","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Characteristic Analysis of Sea Surface Currents around Taiwan Island from CODAR Observations"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3662-470X","authenticated-orcid":false,"given":"Yu-Hao","family":"Tseng","sequence":"first","affiliation":[{"name":"Department of Marine Environment Informatics, National Taiwan Ocean University, Keelung 202301, Taiwan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3822-9324","authenticated-orcid":false,"given":"Ching-Yuan","family":"Lu","sequence":"additional","affiliation":[{"name":"Department of Marine Environment Informatics, National Taiwan Ocean University, Keelung 202301, Taiwan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1560-1370","authenticated-orcid":false,"given":"Quanan","family":"Zheng","sequence":"additional","affiliation":[{"name":"Department of Atmospheric and Oceanic Science, University of Maryland, College Park, MD 20742, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7629-2765","authenticated-orcid":false,"given":"Chung-Ru","family":"Ho","sequence":"additional","affiliation":[{"name":"Department of Marine Environment Informatics, National Taiwan Ocean University, Keelung 202301, Taiwan"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2129","DOI":"10.1002\/2013JC009548","article-title":"Modulation of Kuroshio transport by mesoscale eddies at the Luzon Strait entrance","volume":"119","author":"Lien","year":"2014","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"8098","DOI":"10.1002\/2015GL065814","article-title":"Eddy-Kuroshio interaction processes revealed by mooring observations off Taiwan and Luzon","volume":"42","author":"Tsai","year":"2015","journal-title":"Geophys. Res. Lett."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"427","DOI":"10.1007\/s10872-017-0411-7","article-title":"Statistical features of eddies approaching the Kuroshio east of Taiwan Island and Luzon Island","volume":"73","author":"Cheng","year":"2017","journal-title":"J. Oceanogr."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.dsr.2017.11.006","article-title":"Zonal migration and transport variations of the Kuroshio east of Taiwan induced by eddy impingements","volume":"131","author":"Chang","year":"2018","journal-title":"Deep-Sea Res. PT I"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1007\/s13131-019-1411-9","article-title":"A case study of a Kuroshio main path cut-off event and impacts on the South China Sea in fall-winter 2013-2014","volume":"38","author":"Zheng","year":"2019","journal-title":"Acta Oceanol. Sin."},{"key":"ref_6","first-page":"195","article-title":"Development of a nowcast system for the Taiwan Strait (TSNOW): Numerical simulation of barotropic tides","volume":"23","author":"Jan","year":"2001","journal-title":"Ocean. Polar Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1007\/BF02110430","article-title":"A note on the driving mechanisms of current in the Taiwan Strait","volume":"42","author":"Chuang","year":"1986","journal-title":"J. Oceanogr."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"449","DOI":"10.1109\/JOE.2016.2572818","article-title":"Surface current characteristics in the Taiwan Strait observed by high-frequency radars","volume":"42","author":"Lai","year":"2016","journal-title":"IEEE J. Ocean. Eng."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Lipa, B., Barrick, D., and Isaacson, J. (2019). Evaluating hf coastal radar site performance for tsunami warning. Remote Sens., 11.","DOI":"10.3390\/rs11232773"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"164","DOI":"10.3389\/fmars.2019.00164","article-title":"The global high frequency radar network","volume":"6","author":"Roarty","year":"2019","journal-title":"Front. Mar. Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1007\/s12601-013-0007-0","article-title":"An overview of developments and applications of oceanographic radar networks in Asia and Oceania countries","volume":"48","author":"Fujii","year":"2013","journal-title":"Ocean. Sci. J."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1038\/175681a0","article-title":"Doppler spectrum of sea echo at 13.56 Mc.\/s","volume":"175","author":"Crombie","year":"1955","journal-title":"Nature"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1126\/science.198.4313.138","article-title":"Ocean surface currents mapped by radar","volume":"198","author":"Barrick","year":"1977","journal-title":"Science"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1146\/annurev-marine-121211-172315","article-title":"High-frequency radar observations of ocean surface currents","volume":"5","author":"Paduan","year":"2013","journal-title":"Annu. Rev. Mar. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1839","DOI":"10.1175\/1520-0426(2003)020<1839:ECADFF>2.0.CO;2","article-title":"EOF Calculations and Data Filling from Incomplete Oceanographic Datasets","volume":"20","author":"Beckers","year":"2003","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_16","unstructured":"Liu, A.K., Ho, C.R., and Liu, C.T. (2008). Satellite observation of the cold water around the Hainan Island. Satellite Remote Sensing of South China Sea, Tingmao Publish Company."},{"key":"ref_17","unstructured":"Thomson, R.E., and Emery, W.J. (2014). Data Analysis Methods in Physical Oceanography, Elsevier. [3rd ed.]."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"5","DOI":"10.12681\/mms.64","article-title":"Data Interpolating Empirical Orthogonal Functions (DINEOF): A tool for geophysical data analyses","volume":"12","author":"Barth","year":"2011","journal-title":"Mediterr. Mar. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1109\/LGRS.2019.2920092","article-title":"Radio frequency interference suppression for HF surface wave radar using CEMD and temporal windowing methods","volume":"17","author":"Nazari","year":"2019","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"707","DOI":"10.1007\/s10872-016-0365-1","article-title":"Reconstruction and analysis of long-term satellite-derived sea surface temperature for the South China Sea","volume":"72","author":"Huynh","year":"2016","journal-title":"J. Oceanogr."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Ping, B., Su, F., and Meng, Y. (2016). An improved DINEOF algorithm for filling missing values in spatio-temporal sea surface temperature data. PLoS ONE, 11.","DOI":"10.1371\/journal.pone.0155928"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"L13309","DOI":"10.1029\/2004GL020303","article-title":"ENSO effect on the sea surface wind and sea surface temperature in the Taiwan Strait","volume":"31","author":"Kuo","year":"2004","journal-title":"Geophys. Res. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"699","DOI":"10.1175\/1520-0493(1982)110<0699:SEITEO>2.0.CO;2","article-title":"Sampling errors in the estimation of empirical orthogonal functions","volume":"110","author":"North","year":"1982","journal-title":"Mon. Weather Rev."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1825","DOI":"10.1002\/2014JC010614","article-title":"Large variability of the Kuroshio at 23.75 N east of Taiwan","volume":"120","author":"Jan","year":"2015","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"320","DOI":"10.1016\/S0034-4257(99)00094-2","article-title":"Dynamically active areas in the South China Sea detected from TOPEX\/POSEIDON satellite altimeter data","volume":"71","author":"Ho","year":"2000","journal-title":"Remote Sens. Environ."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"4305","DOI":"10.1002\/jgrc.20323","article-title":"Seasonal to interannual variations in the intensity and central position of the surface Kuroshio east of Taiwan","volume":"118","author":"Hsin","year":"2013","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"22143","DOI":"10.1029\/2000JC000535","article-title":"Mean transport and seasonal cycle of the Kuroshio east of Taiwan with comparison to the Florida Current","volume":"106","author":"Lee","year":"2001","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1007\/s10872-011-0026-3","article-title":"Numerical study on the interactions between a mesoscale eddy and a western boundary current","volume":"67","author":"Kuo","year":"2011","journal-title":"J. Oceanogr."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"C04002","DOI":"10.1029\/2007JC004485","article-title":"Spatial and temporal variations of the Kuroshio east of Taiwan, 1982\u20132005: A numerical study","volume":"113","author":"Hsin","year":"2008","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"5055","DOI":"10.1109\/JSTARS.2016.2524698","article-title":"Effects of cold eddy on Kuroshio meander and its surface properties, east of Taiwan","volume":"9","author":"Hsu","year":"2016","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1175\/2009JPO4285.1","article-title":"Interannual variability of the North Pacific Subtropical Countercurrent and its associated mesoscale eddy field","volume":"40","author":"Qiu","year":"2010","journal-title":"J. Phys. Oceanogr."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/15\/3025\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:38:50Z","timestamp":1760164730000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/15\/3025"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,8,1]]},"references-count":31,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2021,8]]}},"alternative-id":["rs13153025"],"URL":"https:\/\/doi.org\/10.3390\/rs13153025","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2021,8,1]]}}}