High current speed events in a harbor channel driven by resonant sub-hourly sea level dynamics: an example from Varna, Black Sea

Elken, Jüri; Piho, Laura; Kruusmaa, Maarja

doi:10.5194/os-22-2471-2026

Articles | Volume 22, issue 4

https://doi.org/10.5194/os-22-2471-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/os-22-2471-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 22, issue 4

Research article

|

17 Aug 2026

Research article |

| 17 Aug 2026

High current speed events in a harbor channel driven by resonant sub-hourly sea level dynamics: an example from Varna, Black Sea

Jüri Elken, Laura Piho, and Maarja Kruusmaa

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Cited articles

Abbs, D. J. and Physick, W. L.: Sea-breeze observations and modelling: a review, Aust. Meteorol. Mag., 41, 7–19, https://doi.org/10.1071/ES92031, 1992.

Balić, M. and Šepić, J.: SHELDA: Sub-hourly European Quality Controlled Sea Level Dataset, Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2025-767, in review, 2025.

Barantiev, D., Novitsky, M., and Batchvarova, E.: Meteorological observations of the coastal boundary layer structure at the Bulgarian Black Sea coast, Adv. Sci. Res., 6, 251–259, https://doi.org/10.5194/asr-6-251-2011, 2011.

Barzandeh, A., Ličer, M., Rus, M., Kristan, M., Maljutenko, I., Elken, J., Lagemaa, P., and Uiboupin, R.: Application of the HIDRA2 deep-learning model for sea level forecasting along the Estonian coast of the Baltic Sea, Ocean Sci., 21, 1315–1327, https://doi.org/10.5194/os-21-1315-2025, 2025.

Catalán, P. A., Cortés, P. I., Sáez, F., Carvajal, M., and Cienfuegos, R.: Toward the classification of bays based on their resonant response to tsunamis, J. Geophys. Res.-Oceans, 130, e2025JC022446, https://doi.org/10.1029/2025JC022446, 2025.

Egerer, M., Ristolainen, A., Piho, L., Vihman, L., and Kruusmaa, M.: Hall Effect Sensor-Based Low-Cost Flow Monitoring Device: Design and Validation, IEEE Sens. J., 24, 5986–5997, https://doi.org/10.1109/JSEN.2024.3354194, 2024.

Egerer, M., Piho, L., Zhakanov, B., Kruusmaa, M., Ganchev, T., Stanev, A., Todorov, M., and Ristolainen, A.: Exploring Hydrodynamic Patterns Using the Hydromast: Varna Port Case Study, in: OCEANS 2025 Brest, IEEE, 1–7, https://doi.org/10.1109/OCEANS58557.2025.11104387, 2025.

Elken, J., Barzandeh, A., Maljutenko, I., and Rikka, S.: Reconstruction of Baltic Gridded Sea Levels from Tide Gauge and Altimetry Observations Using Spatiotemporal Statistics from Reanalysis, Remote Sens., 16, https://doi.org/10.3390/rs16152702, 2024.

Gao, J., Ji, C., Gaidai, O., and Liu, Y.: Numerical study of infragravity waves amplification during harbor resonance, Ocean Eng., 116, 90–100, https://doi.org/10.1016/j.oceaneng.2016.02.032, 2016.

Giese, G. S. and Chapman, D. C.: Coastal seiches, Oceanus, 36, 38–46, 1993.

Hill, D. F.: Transient and steady-state amplitudes of forced waves in rectangular basins, Phys. Fluids, 15, 1576–1587, https://doi.org/10.1063/1.1569917, 2003.

Kanarik, H., Tuomi, L., Alenius, P., Miettunen, E., Johansson, M., Roine, T., Westerlund, A., and Kahma, K. K.: Currents and their drivers in the Archipelago Sea: insights from ADCP measurements, Ocean Sci., 21, 2125–2147, https://doi.org/10.5194/os-21-2125-2025, 2025.

Kärnä, T., Ljungemyr, P., Falahat, S., Ringgaard, I., Axell, L., Korabel, V., Murawski, J., Maljutenko, I., Lindenthal, A., Jandt-Scheelke, S., Verjovkina, S., Lorkowski, I., Lagemaa, P., She, J., Tuomi, L., Nord, A., and Huess, V.: Nemo-Nordic 2.0: operational marine forecast model for the Baltic Sea, Geosci. Model Dev., 14, 5731–5749, https://doi.org/10.5194/gmd-14-5731-2021, 2021.

LeBlond, P. H. and Mysak, L. A.: Waves in the Ocean, Elsevier Oceanography Series, Vol. 20, Elsevier, ISBN 9780080879772, 1981.

Lighthill, M. J. and Whitham, G. B.: On kinematic waves I. Flood movement in long rivers, P. R. Soc. Lond. A, 229, 281–316, https://doi.org/10.1098/rspa.1955.0088, 1955.

Luettich Jr, R. A., Carr, S. D., Reynolds-Fleming, J. V., Fulcher, C. W., and McNinch, J. E.: Semi-diurnal seiching in a shallow, micro-tidal lagoonal estuary, Cont. Shelf Res., 22, 1669–1681, https://doi.org/10.1016/S0278-4343(02)00031-6, 2002.

Maas, L. R.: On the nonlinear Helmholtz response of almost-enclosed tidal basins with sloping bottoms, J. Fluid Mech., 349, 361–380, https://doi.org/10.1017/S0022112097006824, 1997.

Medvedev, I. P.: Numerical Modeling of Meteorological Sea Level Oscillations in the Black Sea, Oceanology, 62, 471–481, https://doi.org/10.1134/S0001437022040087, 2022.

Medvedev, I. P. and Kulikov, E. A.: Spectrum of Mesoscale Sea Level Oscillations in the Northern Black Sea: Tides, Seiches, and Inertial Oscillations, Oceanology, 56, 6–13, https://doi.org/10.1134/S0001437016010094, 2016.

Medvedev, I. P., Rabinovich, A. B., and Šepić, J.: Destructive coastal sea level oscillations generated by Typhoon Maysak in the Sea of Japan in September 2020, Sci. Rep., 12, 8463, https://doi.org/10.1038/s41598-022-12189-2, 2022.

Méhauté, B. L., Wilson, B. W., Miles, J., and Munk, W.: Closure to “Harbor Paradox”, J. Waterway Div.-ASCE, 88, 173–195, https://doi.org/10.1061/JWHEAU.0000275, 1962.

Miles, J. and Munk, W.: Harbor paradox, J. Waterway Div.-ASCE, 87, 111–132, https://doi.org/10.1061/JWHEAU.0000223, 1961.

Miles, J. W.: Harbor seiching, Annu. Rev. Fluid Mech., 6, 17–33, https://doi.org/10.1146/annurev.fl.06.010174.000313, 1974.

Miles, J. W. and Lee, Y. K.: Helmholtz resonance of harbours, J. Fluid Mech., 67, 445–464, https://doi.org/10.1017/S0022112075000407, 1975.

Miller, A. and Luscher, A.: NOAA's national water level observation network (NWLON), J. Oper. Oceanogr., 12, S57–S66, https://doi.org/10.1080/1755876X.2018.1523301, 2019.

Mohr, S., Kunz, M., Richter, A., and Ruck, B.: Statistical characteristics of convective wind gusts in Germany, Nat. Hazards Earth Syst. Sci., 17, 957–969, https://doi.org/10.5194/nhess-17-957-2017, 2017.

Nesteckyt $\dot{e}$ , L., Kelpšait $\dot{e}$ -Rimkien $\dot{e}$ , L., and Rabinovich, A. B.: Hazardous meteotsunami-like sea-level oscillations in the Port of Klaipeda, the Baltic Sea, Nat. Hazards, 120, 2909–2928, https://doi.org/10.1007/s11069-023-06311-4, 2024.

Panaitescu, F. V., Panaitescu, M., Panait, C., Scupi, A. A., Stan, L., Faitar, C., Suciu, G., Silion, M., Stefanescu, S., Capbun, N., and Zlatev, N.: Metocean specifications for wind data base on the Black Sea, J. Mar. Techn. Envir., 2, 58–64, https://doi.org/10.53464/JMTE.02.2023.10, 2023.

ORDER No Z-160/VARNA: 6 March 2026, Capt. VALENTIN ENCHEV, Director of Maritime Administration, Varna Directorate, Harbour Master of port of Varna, https://www.marad.bg/sites/default/files/upload/documents/2026-04/Order 160-2026_0.pdf (last access: 6 July 2026), 2026.

Park, J., MacMahan, J., Sweet, W. V., and Kotun, K.: Continuous seiche in bays and harbors, Ocean Sci., 12, 355–368, https://doi.org/10.5194/os-12-355-2016, 2016.

Pellikka, H., Šepić, J., Lehtonen, I., and Vilibić, I.: Meteotsunamis in the northern Baltic Sea and their relation to synoptic patterns, Weather Clim. Extrem., 38, https://doi.org/10.1016/j.wace.2022.100527, 2022.

Piho, L. and Ristolainen, A.: Water Flow Velocity, Direction, and Pressure Measurements in Varna Port (February-May 2025), TalTech Data Repository [data set], https://doi.org/10.48726/x61m4-dgg28, 2026.

Rabinovich, A. B.: Seiches and harbor oscillations, in: Handbook of Coastal and Ocean Engineering, edited by: Kim, Y. C., World Scientific, Singapore, 193–236, ISBN 9789814470605, 2009.

Ramos-Alcántara, J., Agulles, M., Gomis, D., and Jordà, G.: Quantifying the contributors to extreme sea level events in a Mediterranean microtidal region at high spatio-temporal resolution, Clim. Dynam., 63, https://doi.org/10.1007/s00382-025-07653-4, 2025.

Ruić, K., Šepić, J., Mlinar, M., and Međugorac, I.: Contribution of high-frequency (T<2 h) sea level oscillations to the Adriatic sea level maxima, Nat. Hazards, 116, 3747–3777, https://doi.org/10.1007/s11069-023-05834-0, 2023.

Sammartino, S., Garrido, J. S., Delgado, J., Naranjo, C., Aldeanueva, F. C., and Lafuente, J. G.: Experimental and numerical characterization of harbor oscillations in the port of Málaga, Spain, Ocean Eng., 88, 110–119, https://doi.org/10.1016/j.oceaneng.2014.06.011, 2014.

Seo, J. Y., Choi, B. J., Choi, S. M., Ryu, J., and Ha, H. K.: Contribution of coastal seiches to sediment transport in a microtidal semi-enclosed bay, Front. Mar. Sci., 11, https://doi.org/10.3389/fmars.2024.1392435, 2024.

Šepić, J., Vilibić, I., Rabinovich, A. B., and Monserrat, S.: Widespread tsunami-like waves of 23–27 June in the Mediterranean and Black Seas generated by high-altitude atmospheric forcing, Sci. Rep., 5, https://doi.org/10.1038/srep11682, 2015.

Stanev, E. V.: Understanding Black Sea dynamics: overview of recent numerical modelling, Oceanography, 18, 56–75, https://doi.org/10.5670/oceanog.2005.42, 2005.

Stanev, E. V. and Ricker, M.: The Fate of Marine Litter in Semi-Enclosed Seas: A Case Study of the Black Sea, Front. Mar. Sci., 6, https://doi.org/10.3389/fmars.2019.00660, 2019.

Steinheuer, J., Beyrich, F., and Löhnert, U.: Exploiting the full potential of Doppler lidars: High-resolution wind-gust profiling in significant weather, Q. J. Roy. Meteor. Soc., 151, e4961, https://doi.org/10.1002/qj.4961, 2025.

Sun, Q. and Niu, X.: Harbor resonance triggered by atmospherically driven edge waves, Ocean Eng., 224, 108735, https://doi.org/10.1016/j.oceaneng.2021.108735, 2021.

Teng, M. H. and Wu, T. Y.: Nonlinear water waves in channels of arbitrary shape, J. Fluid Mech., 242, 211–233, https://doi.org/10.1017/S0022112092002349, 1992.

Trukhchev, D., Bachvarova, E., Krastev, A., and Georgiev, S.: Features of the Hydrological Structure of Varna Lakes and the Atmospheric Impact on the Water Area in the Period 2022–2023, Proc. Bulg. Acad. Sci., 78, 873–883, https://doi.org/10.7546/CRABS.2025.06.10, 2025.

Valiani, A. and Caleffi, V.: A one-dimensional augmented Shallow Water Equations system for channels of arbitrary cross-section, Adv. Water Res., 189, https://doi.org/10.1016/j.advwatres.2024.104735, 2024.

Van der Hoven, I.: Power spectrum of horizontal wind speed in the frequency range from 0.0007 to 900 cycles per hour, J. Meteorol., 14, 160–164, https://doi.org/10.1175/1520-0469(1957)014<0160:PSOHWS>2.0.CO;2, 1957.

Vilibić, I., Denamiel, C., Zemunik, P., and Monserrat, S.: The Mediterranean and Black Sea meteotsunamis: an overview, Nat. Hazards, 106, 1223–1267, https://doi.org/10.1007/s11069-020-04306-z, 2021.

Vilibić, I., Zemunik Selak, P., and Šepić, J.: Meteorological tsunamis: from local hazard to global relevance, Rev. Geophys., 63, e2024RG000867, https://doi.org/10.1029/2024RG000867, 2025.

Williams, D. A., Horsburgh, K. J., Schultz, D. M., and Hughes, C. W.: Proudman resonance with tides, bathymetry and variable atmospheric forcings, Nat. Hazards., 106, 1169–1194, https://doi.org/10.1007/s11069-020-03896-y, 2021.

Yakushev, E., Berezina, A., Yakubov, S., Novikov, M., Ghaffari, P., Dzhurova, B., Hristova, O., Vogt, R., and Ranneklev, S.: Model-based analysis of seasonal hypoxia: The Varna Lake–Bay case study, Ecol. Mod., 515, https://doi.org/10.1016/j.ecolmodel.2026.111535, 2026.

Zheng, Z., Dong, G., and Ma, X.: Special modes with narrow amplification diagrams in harbor oscillations: definition and parametric study, Ocean Dynam., 74, 511–523, https://doi.org/10.1007/s10236-024-01616-9, 2024.

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Three novel Hydromast stations revealed occasional high-amplitude current and water-level oscillations in the 2.4-km-long navigation channel, with dominant periods of 37 and 19 minutes. The oscillation events reflect resonant long-wave forcing from the open sea. The maximum changes in currents and sea level – 0.8 m s⁻¹ and 0.8 m – are harmful to ship navigation, harbor operations, and coastal management. Approaches for detecting and forecasting strong sub-hourly oscillations are discussed.

Three novel Hydromast stations revealed occasional high-amplitude current and water-level...

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