Though computer software that performs harmonic tidal analysis of one- and two-dimensional time series has been are available for more than 40 yr (links to software packages are available online at ), many of these codes are restrictive in both the form of the input time series (e.g., regularly sampled, albeit with gaps) and the manner in which nodal correction, astronomical argument, and inference calculations are made (e.g., as adjustments to results from a least squares fit). One of the most successful and widely used approaches has been, and continues to be, harmonic analysis wherein the energy at specific tidal frequencies is determined by a mathematical fitting procedure, usually least squares. Parker (2007) has recently published a guide on the various considerations that are needed, and contemporary approaches that can be used, to carry out accurate tidal analyses and predictions. There have been many advances in tidal analysis and prediction since the earliest documented predictions for the bore on the Chhien-Thang River in China and flood tide at London Bridge in the eleventh and thirteenth centuries, respectively ( Cartwright 1999).
This new software is free as part of the Institute of Ocean Sciences (IOS) Tidal Package and can be downloaded, along with sample input data and an explanatory readme file. They are (i) the analysis of ocean station temperature time series spanning 25 yr, and (ii) the analysis of satellite altimetry from a ground track whose proximity to land has led to significant data dropout. This new methodology is evaluated through comparisons with results from old techniques and then applied to two problems that could not have been accurately solved with older software. Specific improvements to traditional methods include the analysis of randomly sampled and/or multiyear data more accurate nodal correction, inference, and astronomical argument adjustments through direct incorporation in the least squares matrix multiconstituent inferences from a single reference constituent correlation matrices and error estimates that facilitate decisions on the selection of constituents for the analysis and a single program that analyzes one- or two-dimensional time series. New computer software that permits more versatility in the harmonic analysis of tidal time series is described and tested.