ESS210B
Prof. Jin-Yi Yu
Harmonic
Analysis
qHarmonic analysis is used to identify the periodic (regular) variations
in geophysical time series.
qIf we have N observations of (xi, yi), the time series y(t) can be approximated by cosine and sine
functions :
qHow many
harmonics (cosine/sine functions) do we need?
In
general, if the number of observations is N, the number of harmonic equal to N/2 (pairs of cosine and sine
functions).
t:
Time
T:
Period of observation = NDt
Ak,
Bk:
Coefficients of kth harmonic