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Estimated seasonal cycles

This map below shows the annual and semi-annual cycles fitted to the longest available window of data at each PSMSL station with 70% of annual data present. These cycles were estimated as part of our trend fitting procedure.

The results for each cycle are presented here as coefficients of the sine wave \[h = A \sin (\omega t + \phi)\] where \(t\) is the time in years, such that the fractional part of \(t\) is zero on midnight at the start of 1st January,
\(\omega\) is \(2\pi\) for the annual cycle, and \(4\pi\) for the semi-annual cycle,
\(A\) is the amplitude of the sine wave, given in metres
\(\phi\) is the phase shift, given here in degrees

< 20	20 to 40	40 to 60	60 to 80	80 to 100	100 to 120	> 120
Amplitude of seasonal cycle, mm

January	February	March	April	May	June	July	August	September	October	November	December
Peak month of annual cycle

January & July	February & August	March & September	April & October	May & November	June & December
Peak months of semi-annual cycle