Heterogeneous tide-surge interaction during co-occurrence of tropical and extratropical cyclones in the radial sand ridges of the southern Yellow Sea

Abstract

The Radial Sand Ridges (RSRs) area in the southern Yellow Sea are subject to tropical and extratropical cyclone activities frequently, in which the special geometry feature and moving stationary tidal system result in complex storm-induced hydrodynamic processes, especially the tide-surge interactions. We studied a rare weather event influenced simultaneously by an extratropical cyclone EX1410 and Typhoon Vongfong as an example to investigate the characteristics of storm surges, wave-surge, and tide-surge interaction in the RSRs area, and applied a high-resolution integrally-coupled ADCIRC+SWAN model, in which the meteorological forcing inputs are simulated by the WRF-ARW model. The model is validated by records from 4 tide gauges and 2 wave buoys along the Yellow Sea coast. Results show that the tide-surge interactions are of considerable regional heterogeneousness. The surge curves at Lusi (in south RSRs) and Jianggang (in middle RSRs) have abrupt falls near the time of low tide, where the peak occurrence time of interaction residuals tend to shift towards the mid-ebb period. Significant increase of bed shear stress in shallow waters was proved the dominant factor to affect the tide-surge interaction in broad tidal flats of the RSRs area. Differently, the interaction pattern in the Xiyang Trough (in north RSRs), showed a unique rising in mid-flood period due to the phase advances of real surge waves in relatively deep waters. Therefore, we suggested to the local flood risk management that the tide-surge interaction tends to alleviate the flooding risk in the RSRs area around the time of high tide, but aggravate the risk on the rising tide in the Xiyang Trough and on the falling tide in large-scale tidal flats of the southern RSRs area.