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Vol. LXXI, No. 1

Towards a Real-Time Tidal Analysis and Prediction

July 30, 2015
May 20, 2015


In the practice of tidal analysis and prediction, the number and kind of astronomical tidal components that are to be included in a tidal model depend on the length of available tidal record and the desired accuracy of prediction. Since tidal frequencies, including shallow water constituents, are distributed unequally in a few narrow frequency bands, an inappropriate selection of tidal constituents to be included in the analysis and prediction may cause the normal equations to become ill-conditioned, or even singular, and the prediction to become poor. This investigation shows how to construct lumped tidal frequencies which better characterize ocean tides with diminishing length of observational series. Further, a sequential tidal analysis model is proposed and an algorithm for its implementation is presented, which can rigorously update a tidal solution when the number of observations increases. The algorithm also brings in automatically additional tidal constituents without a large amount of computation work; the CPU time for this analysis is only about 4 percent of that for the conventional harmonic technique. The sequential algorithm for ocean tidal analysis and prediction has a potential to be used in tide gauge stations for providing continuous up-to-date tidal prediction.