Sea level variability and trends in the Adriatic Sea in 1993-2008 from tide gauges and satellite altimetry

At a given location, the trend of the differences of sea level observations by tide gauges and co-located satellite altimetry gives the vertical land motion, if we assume that the sea level signals are truly common. We find trends statistically significant at the 90% confidence level at two locations, that indicate land uplift along the eastern coast in Rovinj (3.0 ± 1.2 mm/yr) and land subsidence in Marina di Ravenna (−1.5 ± 1.1 mm/yr), while at other locations, e.g. in Trieste (1.3 ± 1.1 mm/yr) the significance is lower. The results agree in general in sign with GPS derived rates, but not in magnitude, like in Marina di Ravenna, where the strong subsidence measured by GPS is related to the local anthropogenic subsidence. The differences are partly explained by the spatial distance between the tide gauge and the co-located altimeter locations.