Relative Contributions of Open‐Ocean Forcing and Local Wind to Sea Level Variability Along the West Coasts of Ocean Basins. Issue 11 (25th November 2022)

• Record Type: Journal Article
• Authors: Lin, Wenqiang; Lin, Hongyang; Hu, Jianyu; Huang, Lingfeng
• Is Part Of: Journal of geophysical research. Volume 127:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-25
• Subjects: Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2022JC019218
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: 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. Plain Language Summary: This study aims to reconstruct sea level at the coast by quantifying relative contributions of local wind forcing and the penetrated open‐ocean signals. The contribution of local wind to coastal sea level is estimated by a linear model, while the contribution of the remote open‐ocean forcing is grounded on a "basin‐to‐coast" dynamical linkage framework. Applying the above model to the East China Sea, we find that the penetration ratio of open‐ocean signals is 0.63, which contributes 34% of the total coastal sea level; the remaining contribution (66%) is induced by the local alongshore wind. The coastal sea level is then reconstructed based on these partitions, and shows a good agreement with the observed monthly sea level from tide gauges. We also apply the framework to reconstruct sea level at the west coast of North Atlantic, and the reconstruction also agrees well with observations. The success in the two applications proves reliability of the proposed dynamical linkage framework, and also provides a promising guide to monitor/forecast sea level at the coast given simply the local and remote wind fields. Key Points: A modified arrested topographic wave model is used to quantify relative contributions of local wind and open‐ocean forcing The penetration of open‐ocean signals to the coast can be estimated based on the proposed "basin‐to‐coast" dynamical linkage framework Reconstructed sea levels agree well with tide‐gauge measurements at the west coasts of North Pacific and North Atlantic