V.P. Butukhanov1, E.B. Atutov2, O.N. Ochirov3

1-3 Institute of Physical Materials Science SB RAS (Ulan-Ude, Russia)

1 vbut1951@gmail.com; 2 evgeniy_atutov@mail.ru; 3 1_2_z@mail.ru

This work is devoted to the analysis of the results of a radar experiment aimed at studying the dynamics of wind waves arising on the lake surface of Lake Baikal under various conditions of wave formation. The observation point was located in the village of Goryachinsk with coordinates 52°59' N and 108°18' E, and was located on the path of three main streams (Sarma, Barguzin, Kultuk), which affect the wind field in the coastal zone almost all year round, and has an open coastline; in clear weather, the opposite coast of Olkhon Island is clearly visible.  At the observation point, wind speed and direction were measured. Meteorological conditions at the observation point were very unstable, wind gusts reached 8 m/s, while the wind direction changed from southwest to west, northwest. To measure the characteristics of the wind, a domestic anemorumbometer M-63M-1 was used. To implement the direct method of measurement, a three-meter milestone with tools was developed and created for recording and measuring wave heights. The installation at a distance of 5 meters from the water's edge was submerged to a depth of 0.95 meters. The digitization of wind waves at the observation point from the video recorder showed good agreement with the preliminary calculation of wave characteristics in shallow water. For the remote method of measuring the wave height, we used a nanosecond radar manufactured at the Institute of High Current Electronics (ISE SB RAS), Tomsk. According to the radar characteristics, the resolution in range and azimuth corresponds to the area of the radar “spot” on the surface of the water, equal to 2.75 m2, and the range resolution is 1.5 m, which allows the “spot” to cover one period of the surface wave at sounding along the normal to the wave front, the angle of incidence of the antenna beam was 84°. Sounding was carried out from the shore at a height of about 3 m relative to the water level; the range to the target was 31 m. The spatiotemporal relationship between the reflected signal and wave height variations over a nine-second wave consecution cycle has been established. While following a linear periodic wave with an average period Tav ≈ 3 s and a wavelength equal to 5.63 m, the period of the reflected signal was determined over a 9-second time interval, which is equal to τav = 2Λ/c ≈ 2·5.63/3·108 ≈ 37.5 ns, where c is the speed of light, 3·108 m/s, Λ is the wavelength of the surface perturbation, m. The reasons for the pulsation of the reflected signal, which are the result of small-scale ripples on steep waves, have been established. The dependence of the backward reflection intensity on the wave height is established. The dependence of the backward reflection coefficient on the height of the waves in the short wave and long-wave parts of the centimeter range is characterized by "saturation", and the rate of "saturation" increases with increasing operating frequency. This is especially noticeable in shallow water near the coast of Lake Baikal at a depth of 0.95 m, saturation occurs at a wave height of 0.6 m.

Butukhanov V.P., Atutov E.B., Ochirov O.N. Radar scattering of wind waves near the coastal zone of Lake Baikal. Radiotekhnika. 2023. V. 87. № 12. P. 56−63. DOI: https://doi.org/10.18127/j00338486-202312-07 (In Russian)

1. Gutnik V.G., Kulemin G.P., Sharapov L.I., Goroshko E.A. Intensivnost' radiolokacionnyh otrazhenij ot vzvolnovannoj morskoj poverhnosti pri malyh uglah skol'zhenija. Radiofizika i radioastronomija. 2003. T. 8. № 2. S. 181-189 (in Russian).
2. Bulatov M.G., Kravcov Ju.A., Lavrova O.Ju., Litovchenko K.C., Mitjagina M.I. i dr. Fizicheskie mehanizmy formirovanija ajerokosmicheskih radiolokacionnyh izobrazhenij okeana. UFN. 2003. T. 173. №1. S. 69-87 (in Russian).
3. Lomukhin Yu.L., Atutov E.B., and Butukhanov V.P. Backward Reflection in the Fresnel Problem. IEEE Trans. Antennas Propag. 2018. Vol. 66. № 4. P. 1838-1845. https://doi.org/ 10.1109/TAP.2018.2800643.
4. Lomuhin Ju.L., Butuhanov V.P. Issledovanie obratnogo otrazhenija vodnyh sred pri ljubyh uglah skol'zhenija. Izvestie vuzov. Fizika. 2017. № 11. S. 61-66. https://doi.org/10.1007/s11182-018-1303z (in Russian).
5. Butukhanov V.P., Lomukhin Y.L., Atutov E.B. Verification of the Model of Backward Reflection Coefficient of Absorbing Media. 2020 7th All-Russian Microwave Conference (RMC). Moscow, Russia. 2020. P. 203-205. https://doi.org/ 10.1109/RMC50626.2020.9312337.
6. Galazij G.I. Bajkal v voprosah i otvetah. Irkutsk: Vostochno-Sibirskoe knizhnoe izdatel'stvo. 1984. 368 s. (in Russian).
7. Bernar Le Meote. Vvedenie v gidrodinamiku i teoriju voln na vode. Pod red. M.S. Grushevskogo. L.: Gidrometeoizdat. 1974. 368 s. (in Russian).
8. Bass F.G., Fuks I.M. Rassejanie voln na statisticheski nerovnoj poverhnosti. M.: Nauka. 1972 (in Russian).
9. Butukhanov V P, Lomukhin Ju L and Atutov E B. Wave structure at radar irradiation of homogeneous absorbing media. Journal of Physics: Conference Series. 2021. 2140 012020/ IOP Publishing. https://doi.org/ 10.1088/1742-6596/2140/1/012020.
10. Lomuhin Ju.L., Butuhanov V.P., Atutov E.B. Modelirovanie radiolokacionnogo otrazhenija i radioizluchenija granichashhih zemnyh sred metodom vynuzhdennyh vstrechnyh voln. Jelektromagnitnye volny i jelektronnye sistemy. 2014. № 12. S. 33-39 (in Russian).