The transient effects reduction of the mean sea level trend estimation (from global tide gauge data) based on cumulative sum (CUSUM) and the continuous wavelet transform (CWT)

The mean sea level (MSL) trends measured by tide gauges are contaminated by transient effects (caused by atmospheric pressure variations, interannual and decadal changes). In this paper, the assessment and reduction of these effects are performed by the utilization of two different cumulative sum (associated with bootstrap resampling scheme to get access reliable confidence intervals for the estimated results) and using time-frequency analysis with the continuous wavelet transform (CWT). The numerical results are illustrated using the tide gauge data, Bridgeport in the USA (over a time period of 47 years) and another nearby station series, New York City (over a time period of 106 years) to demonstrate the ability of the methods in detection of transient effects in the MSL. Due to the ability of the CWT to construct a time-frequency representation of a signal in different detail or resolution, this approach could be used as a powerful tool for detection of the transient effects in tide gauge time series. The numerical results show that the significant reduction of the residuals when using of CWT with respect to the using of cumulative sum method.