A new interpolation scheme for detiding vessel-mounted ADCP data in tidal reach of Yangtze Estuary

Spatiotemporal fitting by the least squares method is commonly applied to separate the mean flow (runoff) and tidal current from vessel-mounted ADCP data in tidal reach. To analyze this technique in an estuary region with interaction of the runoff and tide, three sets of 29-h periods vessel-mounted ADCP data in Yangtze Estuary is tested. A diverse set of basis functions is studied and a nodes determination method, named gradient algorithm, is proposed for comparison purposes. The Green function together with a nodal configuration determined by gradient algorithm is the best option. In general, the semi-major axis of the principal tidal ellipse (M2) is parallel to the riverbank and the phase of shoal waters is ahead of that of thalweg, in keeping with shallow-water tide wave dynamics. Because the tidal currents in Yangtze Estuary are explained by shallow-water tide wave dynamics, the use of the Green function and gradient algorithm in the spatiotemporal fitting by least squares technique is a promising scheme for detiding vessel-mounted ADCP data in shallow-water tide wave dynamics systems.