Assessing the Impact of Wave–Current Interactions on Storm Surges and Waves during Cold Air Outbreaks in the Northern East China Sea

Abstract

Storm surges and disastrous waves induced by cold air outbreaks, a type of severe weather system, often impact the coastal economic development. Using the Climate Forecast System Reanalysis wind product and the Coupled Ocean–Atmosphere–Wave–Sediment Transport model, we developed a coupled numerical model and applied it to examine the interaction between surface gravity waves and ocean currents during cold air outbreaks in two case studies in the northern East China Sea. The results revealed that wave–current interactions improved the simulation accuracy, especially the water level, as verified by tidal station measurements. We conducted sensitivity experiments to explore the spatiotemporal variation of the impact of wave–current interactions on storm surges and waves in the northern East China Sea, away from the coastline. The wave-induced surge (up to 0.4 m) and the wave-induced current (up to 0.5 m/s) were found to be related to the difference between wave direction and current direction. The significant wave height difference (up to 0.5 m) was sensitive to the storm surge nearshore and sensitive to the current field offshore, while the mean wave direction change (up to 40°) was more sensitive to the current field than to the storm surge. Additionally, the wave–current interaction regulated the momentum balance and wave action balance, respectively. By comparison, the momentum residuals of pressure gradient, Coriolis force, Coriolis–Stokes force, and bottom stress, which were pronounced in different areas, were modulated more significantly by the wave effect than other terms. The dominant mechanisms of wave–current interactions on waves included the current-induced modification of energy generation caused by wind input, the current-induced modification of energy dissipation caused by whitecapping, and the current-induced wave advection.

Modeling the Sea Level Response of the Northern East China Sea to Different Types of Extratropical Cyclones

“…In general, the magnitude of each momentum term in the NECS during ETCs was similar to Xu et al (2019) terms. We found that the largest contributions of 𝐴𝐴 𝐴𝐴𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 were from the pressure gradient and the surface stress, which agrees with a previous study in the NECS during a cold wave (Mo et al, 2021). During an ETC or cold wave, the pressure gradient is balanced by the wind stress in nearshore and offshore zones.…”

“…Significant modulation of storm surge by waves occurs mainly in shallow water areas and is strongly dependent on the difference between wave direction and current direction (Mo et al., 2021). To assess the relative importance of the three components (wave‐induced surface stress, wave‐induced bottom stress, and 3‐D wave force), we executed three more diagnostic experiments, Cases 10–12 (Table 2), to separate these components.…”

“…Storm surge induced by cold waves in the NECS has been studied by Mo et al. (2016, 2021). However, research on sea level response to ETCs is limited.…”

“…The extratropical storm surge occupied more than 96% of all storm surges occurring in Laizhou Bay, Bohai Bay, and Liaodong Bay, and occupied over 91% in the Bohai Strait. Storm surge induced by cold waves in the NECS has been studied by Mo et al (2016Mo et al ( , 2021. However, research on sea level response to ETCs is limited.…”

Typhoon Karding (Noru) Storm Surge Analysis Using the Coawst Modeling System

“…Figure 2. Data fields exchanged between each component.In Asia,Mo et al (2021) used COAWST to develop a numerical model and use it to examine the interaction between surface gravity waves and ocean currents during cold air outbreaks in the northern East China Sea in 2014 and 2015, revealing that revealed that wave-current interactions improved the simulation accuracy. Lim Kam Sian et al (2020) provides an examination on the effects of model coupling using COAWST in the simulation of 2014 Typhoon Kalmaegi which passed across the Philippines on its track.…”