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

Select desired plot:
Icon for amplitude < 20 mm Icon for amplitude 20 to 40 mm Icon for amplitude 40 to 60 mm Icon for amplitude 60 to 80 mm Icon for amplitude 80 to 100 mm Icon for amplitude 100 to 120 mm Icon for amplitude > 120 mm
< 20 20 to 40 40 to 60 60 to 80 80 to 100 100 to 120 > 120
Amplitude of seasonal cycle, mm
Icon for peak value in January Icon for peak value in February Icon for peak value in March Icon for peak value in April Icon for peak value in May Icon for peak value in June Icon for peak value in July Icon for peak value in August Icon for peak value in September Icon for peak value in October Icon for peak value in November Icon for peak value in December
January February March April May June July August September October November December
Peak month of annual cycle
Icon for peak value in January Icon for peak value in March Icon for peak value in May Icon for peak value in July Icon for peak value in September Icon for peak value in November
January & July February & August March & September April & October May & November June & December
Peak months of semi-annual cycle