Scaling Analysis of Tide Gauge Data from the East Coast of the United States

Tide gauge data is a composite of many periodic and non-periodic nonlinear inputs including: diurnal tides, storms, tsunamis, rogue waves, and global sea level change. This study uses a power-spectral-density analysis of tidal gauge data to look for and quantify internal persistence (internal correlation) and the locations of temporal changes in persistence. The analysis identifies power scaling functions and the scaling exponent(s), Beta. The stations were selected at locations with different proximity to the open ocean, including bays, harbors, and channels, from Maine to Key West, FL. The data is the NOAA CO-OPS Verified Hourly Station Datum. The length of the data sets ranges from 3 years to 101 years. The hourly data sets were decimated to one record every four hours. All data sets analyzed show three distinct regions of persistence with two inflection points at approximately one day and five days. For times less than one day, the scaling exponent ranges between 0 < Beta < 2.6. For times ranging from 1 to 5 days, the scaling exponent ranges between 1.1 < Beta < 2.1. For times greater than 5 days, the scaling exponent ranges between 0.4 < Beta < 0.9. The analysis indicates that persistence generally decreases as period increases but is stable between the inflection points. At Duck, NC, long term persistence in the tide gauge signal is 0.6 as compared to 0.9 for the biweekly shoreline position signal over twenty years, suggesting a strong correlation between the two and the possibility of using tide gauge data to quantify shoreline mobility over the same time interval.