Typhoon-induced destruction and reconstruction of the coastal current system on the inner shelf of East China Sea

Typhoons frequently occur in the East China Sea, which significantly affect the material transport, marine hydrodynamics, and sedimentary environment of coastal currents in a relatively short time scale. Based on the in-situ observation and satellite remote sensing data, this paper analyzes the influence of five typhoons on the coastal currents of East China Sea in 2019 during different seasons. The typhoons Lekima and Mitag, which passed directly, greatly influenced the coastal current, resulting in the disappearance of the tide signal, and stimulated the current to generate new periodic signals of 3–6 days and 1–3 days, respectively. Typically, the wind of Lekima changed the flow field of the East China Sea Coastal Current (ECSCC) from northeastward to southwestward in summer in a short period, and the southwestward volume transport of the ocean current was 4 times that during periods without typhoon occurrence. The remaining water levels of the Haimen, Jiantao, and Damutu tidal level stations showed maximum water level increases during the observation period, whose values were 1.89, 1.26, and 0.90 m, respectively. Mitag only caused a northeastward current transport during autumn, and the water levels of tidal level stations along the coast increased by more than 0.5 m. However, weak and distant typhoons (Danas, Lingling, and Tapah) caused relatively small changes in ocean currents, along with the corresponding change in water transport and deposition. The results show that local wind accompanying typhoons is the main factor affecting the evolution (destruction and reconstruction) of the coastal current system. Therefore, the evolution of the ECSCC under different typhoons can provide a more comprehensive understanding of the impact of typhoons with different paths and intensities on the coastal current.