Relative Contributions of Open-Ocean Forcing and Local Wind to Sea Level Variability Along the West Coasts of Ocean Basins

This study aims to reconstruct sea level at the coast by quantifying relative contributions of local wind forcing and the penetrated open-ocean signals, and thus to build a dynamical connection that seamlessly links the ocean basin to the coast. A linear, modified arrested topographic wave (ATW) model is used to examine the transmission of interior sea level across the continental shelf and the role of alongshore wind in determining the coastal sea level. The local wind stress substantially influences the coastal sea level but does not affect the transmission of open-ocean signals in the linear framework. Increased bottom friction or gentler slope of shelf favors the penetration of open-ocean signals. This modified ATW model is then applied to the shelf seas of North Pacific and North Atlantic, with model parameters being set according to the realistic features of regional oceanography. The offshore boundary condition is determined by the integrated barotropic and baroclinic ocean responses in the ocean basin and the transmission processes across western boundary currents. Based on the proposed "basin-to-coast" dynamical linkage framework, one can estimate the relative contributions of open-ocean forcing and local wind to the total coastal sea level. According to these partitions, the reconstructed coastal sea levels along the west coasts of North Pacific and North Atlantic on seasonal time scale are in close agreement with tide-gauge observations. The idea and specific calculations of coastal sea level reconstruction could be readily applied to other coasts of the global ocean.