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Extremes and marine storms in the Mediterranean Sea

Extremes and marine storms in the Mediterranean Sea. P.Lionello, Univ. of Lecce, Italy. 1 Intro: GEV and generalities examples from RON and sea level in Venice 2 some insight I): Storm surge trends for Venice 3 generalities on waves and wave modeling

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Extremes and marine storms in the Mediterranean Sea

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  1. Extremes and marine storms in the Mediterranean Sea P.Lionello, Univ. of Lecce, Italy 1 Intro: GEV and generalities examples from RON and sea level in Venice 2 some insight I): Storm surge trends for Venice 3 generalities on waves and wave modeling 4 some insight II): futures scenarios for storminess and implications for waves and surges...

  2. EXTREME VALUE ANALYSIS is well established common paradigm return values for relatively long periods But many of other aspects are in practice mostly specific to the problem, and only general guidelines are available Event definition: a set of independent event, the set should contain many items, but few of them are used Data gathering: long homogeneous series of data from observations or models

  3. Cyclones (winds) , waves and surges 4 NOV. 1966 event Surge and waves SLP and U10

  4. alghero crotone mazara monopoli =0.30±0.14 =0.43±0.15 =0.07±0.28 =-0.10±0.22 =7.420.21 =4.660.14 =4.760.16 =3.700.11 la spezia pescara ponza =0.02±0.17 =-0.10±0.19 =0.17±0.16 =4.820.18 =4.740.15 =4.290.14

  5. alghero crotone monopoli pescara mazara ponza la spezia

  6. Venice surge: Extreme values distribution 1940 to 1969 1970 to 2000 GEV distribution 1940 to 1969 1970 to 2000

  7. EXTREMES WAVES, SURGES IN THE ADRIATIC SEA IN A 2xCO2 SCENARIO P.Lionello, F.Dalan, E.Elvini, A.Nizzero

  8. The common element of wave and surges is WIND More intense cyclones Higher wind speeds Higher waves and storm surges Loss of lives, loss of properties, loss of economic resources, cultural and environmental heritages, increased costs of coastal defences

  9. CONSEQUENCES ON WAVE FIELDS AND STORM SURGE A DOWNSCALING PROCEDURE APPLIED TO THE ADRIATIC SEA

  10. The downscaling procedure consists of two steps. 1) A regional wind field is derived from the sea level pressure field (available every 6 hours) by CCA of the PCA prefiltered fields 2) The surge level and the wave field are computed from the wind field using a barotropic (single layer) circulation model and a spectral wave model (WAM) SIMULATED PREDICTOR PREDICTOR: SLP SIMULATED WAVES AND SURGES STATISTICAL MODEL DYNAMICAL MODELS OF OCEAN WAVES AND STORM SURGES PREDICTAND: U10 SIMULATED PREDICTAND: U10

  11. downscaling downscaling Observations Observations T106 T106 downscaling T106 The downscaling procedure has been tested applying it to the ERA-15 SLP data. The same period has also been simulated using directly the T106 winds. The downscaling produces a large improvement in the simulated Significant Wave Height and surge levels. However, levels during peak events remain underpredicted.

  12. RESULTS: SIGNIFICANT WAVE HEIGHT scenario max 100 years depth OBS 5.1 6.750.6 CTR 5.6 6.10.4 CO2 4.5 5.60.3

  13. CTR CTR CTR MAX FREQUENCY 100-YEAR RETURN VALUES CO2 CO2 CO2

  14. STORM SURGE

  15. Venice: Frequency of surges 800 2000 Are the surges in Venice a result of recent climate changes? Is their frequency related to global processes? East coast of England: Frequency of surges Figs from D.Camuffo, (1993)Theor.Appl.Climatol.47,1-14

  16. Source: Report by P.Canestrelli Surges above 110cm level (reference: fixed reference level) Trend in frequency/intensity of storm surges? Sea level rise 2000 1865 Surges above 110cm level (reference: annual mean sea level)

  17. Trend in frequency/intensity of storm surges? The observed trend is mostly produced by loss of ground level. This has no relation with more intense storms in a changed climate… however, a smaller trend could be present. Is this small trend an indication of what could be expected in a 2XCO2 CLIMATE?

  18. RESULTS: SURGE scenario max 100 years depth 1508 OBS 129 184 128 8 CTR 109 CO2 1258 119

  19. CTR CTR CTR MAX FREQUENCY 100-YEAR RETURN VALUES CO2 CO2 CO2

  20. The doubled CO2 simulation is characterized with more extreme weather events, but the (significant) difference between the two scenarios is small, and not fully significant for Mediterranean region The CO2 scenario presents a marginally diminished wave activity in the southern Adriatic. The two scenarios present substantially equivalent extreme surge levels. There is a minor increase in the CO2 scenario.

  21. THE END Clim. Res. (2002), 22, 147-159, Clim. Res. (2003)23,217-231

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