{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:07:15Z","timestamp":1760234835936,"version":"build-2065373602"},"reference-count":39,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2021,6,24]],"date-time":"2021-06-24T00:00:00Z","timestamp":1624492800000},"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>Strong variability of Ka-band radar backscattering from short wind waves on the surface of water covered with surfactant films in the presence of internal waves (IW) was studied in wave tank experiments. It has been demonstrated that modulation of Ka-band radar return due to IW strongly depends on the relationship between the phase velocity of IW and the velocity of drifting surfactant films. An effect of the strong increase in surfactant concentration was revealed in convergent zones, associated with IW orbital velocities in the presence of a \u201cresonance\u201d surface steady current, the velocity of which was close to the IW phase velocity. A phenomenological model of suppression and modulations in the spectrum of small-scale wind waves due to films and IW was elaborated. It has been shown that backscatter modulation could not be explained by the modulation of free (linear) millimeter-scale Bragg waves, but was associated with the modulation of bound (parasitic) capillary ripples generated by longer, cm\u2013dm-scale waves\u2014a \u201ccascade\u201d modulation mechanism. Theoretical analysis based on the developed model was found to be consistent with experiments. Field observations which qualitatively illustrated the effect of strong modulation of Ka-band radar backscatter due to IW in the presence of resonance drift of surfactant films are presented.<\/jats:p>","DOI":"10.3390\/rs13132462","type":"journal-article","created":{"date-parts":[[2021,6,24]],"date-time":"2021-06-24T11:01:38Z","timestamp":1624532498000},"page":"2462","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Strong Modulation of Short Wind Waves and Ka-Band Radar Return Due to Internal Waves in the Presence of Surface Films. Theory and Experiment"],"prefix":"10.3390","volume":"13","author":[{"given":"Stanislav A.","family":"Ermakov","sequence":"first","affiliation":[{"name":"Institute of Applied Physics, Russian Academy of Sciences, 46 Uljanova Str., 603950 Nizhny Novgorod, Russia"},{"name":"Faculty of Shipbuilding, Hydraulic Engineering and Environmental Protection, Volga State University of Water Transport, 5 Nesterova Str., 603950 Nizhny Novgorod, Russia"},{"name":"Radiophysics Department, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Av., 603950 Nizhny Novgorod, Russia"}]},{"given":"Irina A.","family":"Sergievskaya","sequence":"additional","affiliation":[{"name":"Institute of Applied Physics, Russian Academy of Sciences, 46 Uljanova Str., 603950 Nizhny Novgorod, Russia"},{"name":"Faculty of Shipbuilding, Hydraulic Engineering and Environmental Protection, Volga State University of Water Transport, 5 Nesterova Str., 603950 Nizhny Novgorod, Russia"},{"name":"Radiophysics Department, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Av., 603950 Nizhny Novgorod, Russia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6845-3119","authenticated-orcid":false,"given":"Ivan A.","family":"Kapustin","sequence":"additional","affiliation":[{"name":"Institute of Applied Physics, Russian Academy of Sciences, 46 Uljanova Str., 603950 Nizhny Novgorod, Russia"},{"name":"Faculty of Shipbuilding, Hydraulic Engineering and Environmental Protection, Volga State University of Water Transport, 5 Nesterova Str., 603950 Nizhny Novgorod, Russia"},{"name":"Radiophysics Department, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Av., 603950 Nizhny Novgorod, Russia"}]}],"member":"1968","published-online":{"date-parts":[[2021,6,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1038\/314245a0","article-title":"Theory of radar imaging of internal waves","volume":"314","author":"Alpers","year":"1985","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1038\/320345a0","article-title":"Intensity modulation in SAR images of internal waves","volume":"320","author":"Thompson","year":"1986","journal-title":"Nature"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"8009","DOI":"10.1029\/97JC02725","article-title":"Role of surface films in ERS SAR signatures of internal waves on the shelf: Part 1. 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