Data accompanying the research on Secular Trends in Global Tides

Bij de Vaate, I.; Slobbe, D. C.; Verlaan, M.


The dataset constists of two files with data obtained in a study on secular trends in global tides derived from satellite altimetry.


- SecularTrends_M2S2O1_GlobalCO.nc
This file contains linear coefficients describing the trend in amplitude and phases of three major tides, based on tidal harmonics computed from global altimetry-derived water levels. 
Water level data was obtained from the TOPEX/Poseidon and Jason satellites (1993 - 2020). Obtained water levels were stacked at the locations of crossovers (only data within 30 km of the crossover was considered),
before tidal harmonic analysis was performed with the software UTide.

Variables in the file:
lat, lon		crossover coordinates
trend[X]a		linear trend in tidal amplitude [mm/year]
flag[X]m		if 1, the trend estimate exceeds its 95% confidence interval based on error propagation of model-derived amplitude uncertainties.
flag[X]d		if 1, the trend estimate exceeds its 95% confidence interval based on error propagation of data-derived amplitude uncertainties (computed by UTide).

where [X] represents the tidal constituent: M2, S2 or O1.


- SecularTrends_M2S2_EuroShelfAT.nc
This file contains linear coefficients describing the trend in amplitude and phases of three major tides, based on tidal harmonics computed from altimetry-derived water levels on the European Shelf. 
Water level data was obtained from the TOPEX/Poseidon and Jason satellites (1993 - 2020). Along-track tidal harmonic analysis was performed with the software UTide.

Variables in the file:
lat, lon		along-track coordinates
trend[X][c]		linear trend in tidal amplitude [mm/year] or phase [deg/year]
flag[X][c]M		if 1, the trend estimate exceeds its 95% confidence interval based on error propagation of model-derived amplitude/phase uncertainties.
flag[X][c]D 		if 1, the trend estimate exceeds its 95% confidence interval based on error propagation of data-derived amplitude/phase uncertainties (computed by UTide).

where [X] represents the tidal constituent: M2, S2 or O1 and [c] the harmonic constant: a (amplitude) or g (phase).