Techniques for analyzing sea level records around New Zealand

For New Zealand, semidiurnal tides account for approximately 96% of the energy and the remaining 4% is attributed to barometric pressure and wind effects, storm surge, and the longer‐term seasonal and interannual fluctuations. Techniques have been developed for identifying each of these components of the sea level signal, involving analysis in both the time domain and the frequency domain. Analysis in the frequency domain is the favored method because the response to specific forcing functions can be identified, but the data should also be analyzed in the time domain to complement the results from the frequency‐domain analysis.