# Amplitude spectrum

From Glossary of Meteorology

## amplitude spectrum

In the Fourier or spectral analysis of two time series, a measure of the correlation between the two series as a function of frequency or wavelength, but ignoring any phase differences between the two time series.

It is defined as where

*n*is wavenumber (number of waves per total period of the time series),*Co*(*n*) is the cospectrum, and*Q*(*n*) is the quadrature spectrum.Stull, R. B. 1988. An Introduction to Boundary Layer Meteorology. 666 pp.