Residual circulation in the English Channel as a dynamically consistent synthesis of shore-based observations of sea level and currents

High frequency (HF) radar surface velocities and coastal tidal gauge data are assimilated into a two-dimensional (2D) finite element spectral in time model to describe the Stokes drift of the major tidal constituents in the English Channel. The numerical model was fit to observations by optimizing the unknown sea surface height at the open boundaries of the domain. Six major tidal constituents, M2, S2, N2, K2, K1, and M4 were subject to the inversion. The assimilated sea surface height and depth averaged velocities are used for mapping of the residual transport through the Channel, tidal dissipation, and for estimation of the energy flux. The respective values obtained are 53±6×103 m3 s−1 for the net combined transport of the residual flow, and 0.75±0.16 W m−2, for the basin-averaged tidal energy dissipation rate. The net horizontal energy flux through the Dover Strait is estimated as 1.40±0.16×1010 W. Analysis of the stream function distribution of the residual flow reveals a number of permanent eddies associated with peculiarities of the coastline shape and inhomogeneities of the bottom topography. form an extensive error analysis of the results via an explicit inversion of the Hessian matrix, associated with the assimilation scheme. Error charts for the sea surface elevation demonstrate the modelʹs ability to fit the data within the error bars in the major part of the model domain and expose coastal areas within the western Channel requiring better coverage by observations.