Tidal analysis on a spreadsheet

摘要

A harmonic analysis of the tides combines astronomical data, Fourier transformation, and nonlinear least-squares analysis. Fourier transformation is used to display the power spectrum of the initial data and, during the subsequent refinement stages of the analysis, of the remaining residuals. Because only a relatively small sample is used, the frequency resolution of the Fourier transformation is insufficient to determine the precise frequencies involved, which are instead taken from astronomical data. The actual fitting of successive terms, in order of decreasing importance, is accomplished with nonlinear least squares. Because both Fourier transformation and nonlinear least-squares fitting are readily automated on a spreadsheet, the amount of computational effort required for this analysis is minimal. (C) 2004 American Association of Physics Teachers.