# Harmonic analysis

From Glossary of Meteorology

## harmonic analysis

- A statistical method for determining the amplitude and period of certain harmonic or wave components in a set of data with the aid of Fourier series.

Harmonic analysis has been used in meteorology, for example, to determine periodicities in climatic data (Conrad 1950); to determine the wavelengths most strongly represented in general circulation flow patterns; and to determine the spectrum of turbulent eddies (Sutton 1953).

- The representation of tidal variations as the sum of several harmonics, each of different period, amplitude, and phase.

The periods fall into three tidal species: long period, diurnal, and semidiurnal. Each tidal species contains groups of harmonics that can be separated by analysis of a month of observations. In turn, each group contains constituents that can be separated by analysis of a year of observations. In shallow water, harmonics are also generated in the third-diurnal, fourth-diurnal, and higher species. These constituents can be used for harmonic prediction of tides.

Conrad, V. 1950. Methods in Climatology. 119–154.

Sutton, O. G. 1953. Micrometeorology. 96–103.