Climate Projection of Maximum Water Level accounting for the Effect of Waves, Storm Surges and Mean Sea Level Changes: an Application to Climate Projections along the Coastline of the Mediterranean Sea

Abstract:

The maximum level that water reaches during a storm depends on changes of mean sea level and storminess. Increase of mean sea level can be caused by mass addition, steric effects and land subsidence. Changes of storminess will change the height of ocean waves and storm surges. This study proposes a methodology for estimating the change of maximum water level at the coast as it results from the superposition of these different factors, and applies it to climate change scenario simulations in the Mediterranean Sea. The analysis is based on a 7-member ensemble of regional climate model simulations covering the period 1951-2050 under the A1B emission scenario. Models that include a high resolution Mediterranean Sea circulation component have been used for diagnosing the steric sea level change. Model sea level pressure and wind fields are used for forcing a hydro-dynamical shallow water model (HYPSE), wind fields are used for forcing a wave model (WAM), obtaining estimates of storm surges and ocean waves, respectively. The climate change signal is computed as the difference between water level maxima in the 1971-2000 and 2021-2050 period. Results show that in the next decades storm surge level and wave height will decrease and partially compensate for the increase of maximum water level produced by the positive steric effect.