Studying Amplification of the Surge Fluctuations in the Level of the Sea of Azov Based on Mathematical Modeling

Amplification of the surge fluctuations in the level of the Sea of Azov caused by the passage of deep small-scale cyclones is studied using the ADCIRC nonlinear longwave hydrodynamic model. The influence of the speed and direction of cyclone movement on the magnitude of surges is investigated for the following coastal settlements: Taganrog, Dolzhanskaya, Primorsko-Akhtarsk, Temryuk, Mysovoe, Genichesk, Berdyansk, and Mariupol. Three types of cyclones whose speeds varied within 3–20 m/s are considered: western, southwestern, and northwestern ones. It has been found that when western and southwestern cyclones pass over the sea, the strongest surges occur mainly when the speed of the cyclone approaches the resonant speed of free long waves in a part of the sea where a coastal settlement is located. The impact of northwestern cyclones on the sea leads to the excitation of the most intense surge oscillations at low cyclone speeds ( $$V = 3$$ m/s) in most of the analyzed settlements. It is shown that consideration of the horizontal gradient of atmospheric pressure in the model can increase the magnitude of surges by 15%. Using atmospheric reanalysis data, the situations when real cyclones moved over the Sea of Azov were simulated. The simulations have shown that the approach of the cyclone speed to the resonant speed can lead to the amplification of surge fluctuations when cyclones move over the sea in the eastern and northeastern directions.