The influence of interannual variability of mean sea level in the Adriatic Sea on extreme values

The analysis of sea level data, in the low and middle Adriatic (south of Italy),collected by 6 stations belonging to the National Tide Gauge Network and to Apulia Region Meteomarine Network, shows a generalized increase in the mean sea level from 2008. The change between 2007 and 2009 is in the order of about 10 cm. A GPD distribution has been fitted to extreme series (5 extremes per year from 1999 to 2012) of sea level observed values, observed levels corrected with current annual mean sea level and tidal residuals. The analysis shows a significant increase in extremes of sea level values, while the extremes of corrected observed values and tidal residuals are quite similar respect to those found using observed data updated to 2006. Due to the sea level increase, the extremes, in observed sea level, rise drastically when updating time series to 2012, but, removing the effect of Mean Sea Level (MSL), these differences significantly decrease in the return levels.