An estimate of the sea level trend along the Tunisia coasts

Abstract

This study evaluates the sea level trend along the Tunisia coasts based on available historical and recent tide gauge observations for the period 1880-2018. The stations used are located in the Tunisia coasts and in the western side of the Strait of Gibraltar. Sea level series based on reanalyses and Mediterranean Sea model simulations are also used. First, a single series representing the western Strait of Gibraltar sea level evolution is constructed. Then, the sea level series along the Tunisia coasts is constructed based on the hypothesis that the observed sea level drop relative to that in the western side of the Strait of Gibraltar remains nearly unchanged when long term periods are considered. The constructed series for the Tunisia coasts shows an evident sea level rise superimposed on a decadal variability in connection with the North Atlantic Oscillation (NAO). For the whole period, the estimated sea level trend is +1.5 mm/year, whereas it is +3mm/y for the recent period 1980- 2015. In addition to the widely accepted of the sea level rise acceleration during the recent decades, this higher trend may also be attributed to the effect of the decadal variability. Projections for the future state of the sea level along the Tunisia coasts are given based on the trend estimates found in this study.