Abstract
Abstract. We present a study on expected wind wave severity changes in the Adriatic Sea for the period 2070–2099 and their impact on extremes. To do so, the phase-averaged spectral wave model SWAN is forced using wind fields computed by the high-resolution regional climate model COSMO-CLM, the climate version of the COSMO meteorological model downscaled from a global climate model running under the IPCC-A1B emission scenario. Namely, the adopted wind fields are given with a horizontal resolution of 14 km and 40 vertical levels, and they are prepared by the Italian Aerospace Research Centre (CIRA). Firstly, in order to infer the wave model accuracy in predicting seasonal variability and extreme events, SWAN results are validated against a control simulation, which covers the period 1965–1994. In particular, numerical predictions of the significant wave height Hs are compared against available in-situ data. Further, a statistical analysis is carried out to estimate changes on wave storms and extremes during the simulated periods (control and future scenario simulations). In particular, the generalized Pareto distribution is used to predict changes of storm peak Hs for frequent and rare storms in the Adriatic Sea. Finally, Borgman's theory is applied to estimate the spatial pattern of the expected maximum wave height Hmax during a storm, both for the present climate and that of the future scenario. Results show a future wave climate in the Adriatic Sea milder than the present climate, even though increases of wave severity can occur locally.
Highlights
The distributions and intensity of wind fields over the Mediterranean Sea (Fig. 1) are expected to change during the 21st century planning horizon, as a result of the anthropogenic climate change due to the enhanced greenhouse effect (IPCC, 2007)
WAM was set at a lat-long resolution of 0.25◦ (≈25 km) and forced by wind fields computed by RegCM (Pal et al, 2000) at 0.60◦ (≈60 km) resolution, under A2 medium-high emission and B2 medium-low emission scenarios. Along this line of thought, and in accordance with the model resolutions suggested by Lionello et al (2012), the present paper aims at quantifying the changes of waves and their extremes in the Adriatic Sea, comparing the present conditions with those expected in the period 2070–2099 under the A1B medium emissions scenario hypothesis
Contrary to Bora, Sirocco is not fetch limited and characterized by a progressive growth; Bora winds can attain very high speed suddenly, Sirocco can grow slowly, reaching the highest speeds in the eastern Adriatic regions, and generally it decreases while proceeding to the western coasts, as pointed out by Signell et al (2005). They have shown how the resolution adopted by numerical weather prediction (NWP) systems is crucial for reproducing accurately dominant and transient winds in the Adriatic region, implicitly suggesting, among other characteristics, that numerical tools with horizontal grid size smaller than 20 km can significantly improve the accuracy of meteorological forcing for wave numerical models
Summary
The distributions and intensity of wind fields over the Mediterranean Sea (Fig. 1) are expected to change during the 21st century planning horizon, as a result of the anthropogenic climate change due to the enhanced greenhouse effect (IPCC, 2007). Contrary to Bora, Sirocco is not fetch limited and characterized by a progressive growth; Bora winds can attain very high speed suddenly, Sirocco can grow slowly, reaching the highest speeds in the eastern Adriatic regions, and generally it decreases while proceeding to the western coasts, as pointed out by Signell et al (2005) They have shown how the resolution adopted by numerical weather prediction (NWP) systems is crucial for reproducing accurately dominant and transient winds in the Adriatic region, implicitly suggesting, among other characteristics, that numerical tools with horizontal grid size smaller than 20 km can significantly improve the accuracy of meteorological forcing for wave numerical models. Some conclusions are drawn and suggestions for future studies are discussed
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