Quantile Analysis of Relative Sea-Level at the Hornbæk and Gedser Tide Gauges
The quantification of the long-term variability of relative sea-level is a fundamental problem in geodesy. In the present study, quantile regression is applied for characterising the long-term variability in relative sea-level at the Gedser and Hornbæk tide gauges, in the North Sea–Baltic Sea transition zone. Quantile regression allows to quantify not only the rate of change in mean sea-level but also in extreme heights, providing a more complete description of long-term variability. At Gedser the lowest relative heights are increasing at a rate approximately 40% higher than the mean rate, while at Hornbæk the relative sea-level slopes are stable across most of the quantiles. A 30-year running window analysis shows that the linear trends display considerable decadal variability over the twentieth century for both stations.
KeywordsOrdinary Little Square Quantile Regression Tide Gauge Glacial Isostatic Adjustment Tide Gauge Record
Thanks are due to R. Koenker for providing the R-package quantreg, to the R development core team for the R software, and to P. Wessel and W.H.F. Smith for the GMT software. This work is supported by FCT (contract under Programme Ciencia 2008).
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