{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:14:38Z","timestamp":1760242478533,"version":"build-2065373602"},"reference-count":53,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2017,9,8]],"date-time":"2017-09-08T00:00:00Z","timestamp":1504828800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>In order to improve the forecasting ability of numerical models, a sequential data assimilation scheme, nudging, was applied to blend remotely sensing high-frequency (HF) radar surface currents with results from a three-dimensional numerical, EFDC (Environmental Fluid Dynamics Code) model. For the first time, this research presents the most appropriate nudging parameters, which were determined from sensitivity experiments. To examine the influence of data assimilation cycle lengths on forecasts and to extend forecasting improvements, the duration of data assimilation cycles was studied through assimilating linearly interpolated temporal radar data. Data assimilation nudging parameters have not been previously analyzed. Assimilation of HF radar measurements at each model computational timestep outperformed those assimilation models using longer data assimilation cycle lengths; root-mean-square error (RMSE) values of both surface velocity components during a 12 h model forecasting period indicated that surface flow fields were significantly improved when implementing nudging assimilation at each model computational timestep. The Data Assimilation Skill Score (DASS) technique was used to quantitatively evaluate forecast improvements. The averaged values of DASS over the data assimilation domain were 26% and 33% for east\u2013west and north\u2013south velocity components, respectively, over the half-day forecasting period. Correlation of Averaged Kinetic Energy (AKE) was improved by more than 10% in the best data assimilation model. Time series of velocity components and surface flow fields were presented to illustrate the improvement resulting from data assimilation application over time.<\/jats:p>","DOI":"10.3390\/rs9090932","type":"journal-article","created":{"date-parts":[[2017,9,8]],"date-time":"2017-09-08T11:34:52Z","timestamp":1504870492000},"page":"932","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Hindcasting and Forecasting of Surface Flow Fields through Assimilating High Frequency Remotely Sensing Radar Data"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9662-8630","authenticated-orcid":false,"given":"Lei","family":"Ren","sequence":"first","affiliation":[{"name":"Department of Civil Engineering, National University of Ireland Galway, H91 TK33 Galway, Ireland"},{"name":"Ryan Institute, H91 TK33 Galway, Ireland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michael","family":"Hartnett","sequence":"additional","affiliation":[{"name":"Department of Civil Engineering, National University of Ireland Galway, H91 TK33 Galway, Ireland"},{"name":"Ryan Institute, H91 TK33 Galway, Ireland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2017,9,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"624","DOI":"10.1007\/s10236-006-0079-9","article-title":"Comparison of reduced-order, sequential and variational data assimilation methods in the tropical Pacific Ocean","volume":"56","author":"Robert","year":"2006","journal-title":"Ocean Dyn."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"181","DOI":"10.2151\/jmsj1965.75.1B_181","article-title":"Unified notation for data assimilation operational, sequential and variational","volume":"75","author":"Ide","year":"1997","journal-title":"J. Meteorol. Soc. Jpn."},{"key":"ref_3","unstructured":"Madsen, H., Hartnack, J., and S\u00f8rensen, J.V.T. (2006, January 19\u201322). Data assimilation in a flood modelling system using the Ensemble Kalman filter. Proceedings of the XVI International Conference on Computational Methods in Water Resources, Copenhagen, Denmark."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1007\/s10236-003-0036-9","article-title":"The Ensemble Kalman Filter: Theoretical formulation and practical implementation","volume":"53","author":"Evensen","year":"2003","journal-title":"Ocean Dyn."},{"key":"ref_5","first-page":"75","article-title":"Assimilation of HF radar-derived surface currents on tidal-timescales","volume":"5","author":"Gopalakrishnan","year":"2012","journal-title":"J. Oper. Oceanogr."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Isern-Fontanet, J., Ballabrera-Poy, J., Turiel, A., and Garcia-Ladona, E. (2017). Retrieval and assimilation of velocities at the ocean surface. Nonlinear Process. Geophys., 1\u201337.","DOI":"10.5194\/npg-2017-14"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1016\/j.pocean.2011.05.004","article-title":"The Regional Ocean Modeling System (ROMS) 4-dimensional variational data assimilation systems: Part I\u2014System overview and formulation","volume":"91","author":"Moore","year":"2011","journal-title":"Prog. Oceanogr."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/j.dynatmoce.2008.11.005","article-title":"Assessing 4D-VAR for dynamical mapping of coastal high-frequency radar in San Diego","volume":"48","author":"Hoteit","year":"2009","journal-title":"Dyn. Atmos. Oceans"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1445","DOI":"10.1002\/qj.2054","article-title":"Operational implementation of a hybrid ensemble\/4D-Var global data assimilation system at the Met Office","volume":"139","author":"Clayton","year":"2013","journal-title":"Q. J. R. Meteorol. Soc."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2085","DOI":"10.1175\/MWR-D-13-00221.1","article-title":"A 4DVAR system for the Navy Coastal Ocean Model. Part I: System description and assimilation of synthetic observations in Monterey Bay","volume":"142","author":"Ngodock","year":"2014","journal-title":"Mon. Weather Rev."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/j.ocemod.2008.08.002","article-title":"4DVAR data assimilation in the Intra-Americas Sea with the Regional Ocean Modeling System (ROMS)","volume":"25","author":"Powell","year":"2008","journal-title":"Ocean Model."},{"key":"ref_12","first-page":"434","article-title":"HF radar data assimilation in the Monterey Bay area","volume":"109","author":"Paduan","year":"2004","journal-title":"J. Geophys. Res."},{"key":"ref_13","first-page":"1","article-title":"Forecasting of surface currents via correcting wind stress with assimilation of high-frequency radar data in a three-dimensional model","volume":"2016","author":"Ren","year":"2016","journal-title":"Adv. Meteorol."},{"key":"ref_14","first-page":"1","article-title":"Assimilation of high-frequency radar currents in a nested model of the West Florida Shelf","volume":"113","author":"Barth","year":"2008","journal-title":"J. Geophys. Res."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1016\/S0924-7963(01)00002-1","article-title":"Real time assimilation of HF radar currents into a coastal ocean model","volume":"28","author":"Breivik","year":"2001","journal-title":"J. Mar. Syst."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1001","DOI":"10.1016\/j.csr.2004.02.013","article-title":"Assimilation of drifter and satellite data in a model of the Northeastern Gulf of Mexico","volume":"24","author":"Fan","year":"2004","journal-title":"Cont. Shelf Res."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/S0924-7963(01)00008-2","article-title":"Prediction of particle trajectories in the Adriatic sea using Lagrangian data assimilation","volume":"29","author":"Castellari","year":"2001","journal-title":"J. Mar. Syst."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Lin, X.H., Oey, L.Y., and Wang, D.P. (2007). Altimetry and drifter data assimilations of loop current and eddies. J. Geophys. Res., 112.","DOI":"10.1029\/2006JC003779"},{"key":"ref_19","unstructured":"Dabrowski, T. (2005). A Flushing Study Analysis of Selected Irish Waterbodies. [Ph.D. Thesis, National University of Ireland Galway]."},{"key":"ref_20","first-page":"96","article-title":"Characterizing observed circulation patterns within a bay using HF radar and numerical model simulations","volume":"142","author":"Hartnett","year":"2014","journal-title":"J. Mar. Syst."},{"key":"ref_21","unstructured":"Wang, J., Dizaji, R., and Ponsford, A.M. (2004, January 2\u20135). Analysis of clutter distribution in bistatic high frequency surface wave radar. Proceedings of the 2004 Canadian Conference on Electrical and Computer Engineering, Niagara Falls, ON, Canada."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1006\/ecss.2000.0704","article-title":"Remote radar measurement of shelf currents off key largo, Florida, U.S.A","volume":"51","author":"Haus","year":"2000","journal-title":"Estuar. Coast. Shelf Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"488","DOI":"10.1016\/j.envsoft.2006.02.010","article-title":"Simulation of constituent transport using a reduced 3D constituent transport model (CTM) driven by HF Radar: Model application and error analysis","volume":"22","author":"Ojo","year":"2007","journal-title":"Environ. Model. Softw."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"12094","DOI":"10.3390\/rs61212094","article-title":"Brahan project high frequency radar ocean measurements: Currents, winds, waves and their interactions","volume":"6","author":"Lipa","year":"2014","journal-title":"Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1190","DOI":"10.3390\/rs1041190","article-title":"HF radar bistatic measurement of surface current velocities: drifter comparisons and radar consistency checks","volume":"1","author":"Lipa","year":"2009","journal-title":"Remote Sens."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1016\/j.dsr2.2008.08.004","article-title":"Assimilation of HF radar-derived radials and total currents in the Monterey Bay area","volume":"56","author":"Shulman","year":"2009","journal-title":"Deep Sea Res. Part II Top. Stud. Oceanogr."},{"key":"ref_27","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":"Ann. Rev. Mar. Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1259","DOI":"10.1175\/1520-0426(2004)021<1259:ERCMFC>2.0.CO;2","article-title":"Evaluating radial current measurements from CODAR high-frequency radars with moored current meters","volume":"21","author":"Emery","year":"2003","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1689","DOI":"10.1175\/2010JTECHO720.1","article-title":"HF Radar performance in a low-energy environment: CODAR SeaSonde experience on the West Florida Shelf","volume":"27","author":"Liu","year":"2010","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_30","unstructured":"Hamrick, J.M. (2006). EFDC Technical Memorandum."},{"key":"ref_31","unstructured":"TetraTech (2007). The Environmental Fluid Dynamics Code Theory and Computation Volume 1: Hydrodynamics and Mass Transport, Tetra Tech, Inc."},{"key":"ref_32","unstructured":"Hamrick, J.M. (1992). A Three-Dimensional Environmental Fluid Dynamics Computer Code: Therotical and Computatonal Aspects, Virginia Institute of Marine Science."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"555","DOI":"10.1061\/(ASCE)0733-9372(2006)132:4(555)","article-title":"An integrated hydrodynamic and water quality modeling system to support nutrient TMDL development for Wissahickon Creek","volume":"132","author":"Zou","year":"2006","journal-title":"J. Environ. Eng."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1055","DOI":"10.1061\/(ASCE)0733-9429(2004)130:11(1055)","article-title":"Case Study: Modeling of sediment transport and wind-wave impact in Lake Okeechobee","volume":"130","author":"Jin","year":"2004","journal-title":"J. Hydraul. Eng."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.aquaeng.2012.07.006","article-title":"Physical and numerical investigation of the hydrodynamic implications of aquaculture farms","volume":"52","author":"Hartnett","year":"2013","journal-title":"Aquac. Eng."},{"key":"ref_36","unstructured":"Wen, L. (1995). Three-Dimensional Hydrodynamic Modelling in Galway Bay, University College Galway."},{"key":"ref_37","unstructured":"Nagle, D. (2013). Modelling and Observation of Wind-Driven Circulation in Galway Bay, National University of Ireland Galway."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1016\/j.wse.2015.12.001","article-title":"Observation and modeling of tide- and wind-induced surface currents at Galway Bay","volume":"8","author":"Ren","year":"2015","journal-title":"Water Sci. Eng."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1175\/1520-0426(2002)019<0183:EIMOBO>2.0.CO;2","article-title":"Efficient inverse modeling of barotropic ocean tides","volume":"19","author":"Egbert","year":"2002","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2003GL019003","article-title":"A barotropic inverse tidal model for the Arctic Ocean","volume":"31","author":"Padman","year":"2004","journal-title":"Geophys. Res. Lett."},{"key":"ref_41","unstructured":"Gopalakrishnan, G. (2008). Surface Current Observations Using High Frequency Radar and Its Assimilation into the New York Harbor Observing and Prediction System. [Ph.D. Thesis, Stevens Institute of Technology]."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"3405","DOI":"10.1029\/1998WR900001","article-title":"Integration of soil moisture remote sensing and hydrologic modeling using data assimilation","volume":"34","author":"Houser","year":"1998","journal-title":"Water Resour. Res."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"126","DOI":"10.1016\/j.ocemod.2015.07.016","article-title":"Impact of assimilating altimeter data on wave predictions in the western Iberian coast","volume":"96","author":"Rusu","year":"2015","journal-title":"Ocean Model."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1250","DOI":"10.1175\/1520-0493(1990)118<1250:UOFDDA>2.0.CO;2","article-title":"Use of four-dimensional data assimilation in a limited-area mesoscale model. Part I: Experiments with synoptic-scale data","volume":"118","author":"Stauffer","year":"1990","journal-title":"Mon. Weather Rev."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"3439","DOI":"10.1256\/qj.05.149","article-title":"Convective-scale assimilation of radar data: Progress and challenges","volume":"131","author":"Sun","year":"2005","journal-title":"Q. J. R. Meteorol. Soc."},{"key":"ref_46","unstructured":"Agostinho, P., Gil, A., and Galeano, J.C. (2012). N.U.I Galway CODAR SeaSonde HF Radar System, Qualitas Remos."},{"key":"ref_47","unstructured":"Soares, C.G. (2015). Renewable energies offshore. Chapter 24 Data Assimilation with High-Frequency (HF) Radar Surface Currents at a Marine Renewable Energy Test Site, CRC Press."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1007\/BF02108528","article-title":"Local balance in the air-sea boundary processes","volume":"29","author":"Toba","year":"1973","journal-title":"J. Oceanogr. Soc. Jpn."},{"key":"ref_49","unstructured":"Ren, L., Hartnett, M., and Nash, S. (July, January 28). Assessment methods of data assimilation in oceanographic model forecasting. Proceedings of the 36th IAHR World Congress, Delft, The Netherlands."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"669","DOI":"10.5194\/gmd-3-669-2010","article-title":"Physically-based data assimilation","volume":"3","author":"Levy","year":"2010","journal-title":"Geosci. Model Dev."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"572","DOI":"10.1007\/s11802-014-2224-2","article-title":"Assimilation of high frequency radar data into a shelf sea circulation model","volume":"13","author":"Xu","year":"2014","journal-title":"J. Ocean Univ. China"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"994","DOI":"10.1175\/1520-0493(1976)104<0994:ACFFOA>2.0.CO;2","article-title":"Anisotropic correction functions for objective analysis","volume":"104","author":"Thiebaux","year":"1976","journal-title":"Mon. Weather Rev."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1007\/s13131-013-0328-y","article-title":"Assimilation of surface currents into a regional model over Qingdao coastal waters of China","volume":"32","author":"Zhao","year":"2013","journal-title":"Acta Oceanol. Sin."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/9\/9\/932\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:44:27Z","timestamp":1760208267000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/9\/9\/932"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,9,8]]},"references-count":53,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2017,9]]}},"alternative-id":["rs9090932"],"URL":"https:\/\/doi.org\/10.3390\/rs9090932","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2017,9,8]]}}}