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.
Highlights
Storm surges and huge waves induced by cold air outbreaks (CAOs, known as cold waves) adversely affect the economic development of coastal cities [1,2,3]
maxima relative error (MRE) represents the relative error of the extreme values in the time series of simulation; RMSE represents the root-mean-square error between the time series of observation and the time series of simulation; CC represents the correlation coefficient between the time series of observation and the time series of simulation
During the CAO-induced generalized northwest (GNW) wind, the variation of surge difference, which ranged from −0.40 to 0.20 m, was consistent with the storm surge in the NECS
Summary
Storm surges and huge waves induced by cold air outbreaks (CAOs, known as cold waves) adversely affect the economic development of coastal cities [1,2,3]. Researchers have simulated the marine dynamic environment during CAOs using numerical models and hindcasted the water level, currents, and waves separately [4,5,6]. The relative wind effect is an important wave–current interaction mechanism and is able to generate 20–40% current modulation for wave height [15]. The Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system was developed by Warner et al [44] from the U.S Geological Survey, Coastal and Marine Science Center, Woods Hole, United States This coupling system has been widely used to study near-shore physical processes on a regional scale [13,45,46]. The added term on the left side of Equations (11) and (12) is the Stokes–Coriolis force (StCOR), and the added terms on the right side are the horizontal vortex force (HVF) and the vertical vortex force (VVF)
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