1. Mediterranean Sea Level Variability Changes and Projections at High Frequencies (1-100 Days) Ivica Vilibic, Jadranka Sepic Institut of Oceanography and Fisheries, Split, Croatia Gabriel Jordà, Marta Marcos IMEDEA (CSIC-UIB), Palma de Mallorca, Spain

2. Motivation 1.More attention has been paid to the MSL projections than to sea level extremes. 2.Regional sea level extreme climate projections are just now ‘being born’ for the Mediterranean. 3.What about short timescales (less than few months) contributors to the sea level variability (SLV) and extremes, about their present climate patterns and future projections? 4.Does SLV climate projections differ over frequencies?

3. To ‘slightly’ bridge that problem we 1.Applied 2D ocean climate model to the Mediterranean, forced by reanalysis atmospheric fields (hindcast run) and GHG+aerosol from RegCM (control run + B1, A1B, A2 projections) 2.Extracted SLV patterns over different frequency bands (1-3, 3-10, 10-100 days) by applying digital band-pass filtering to the sea level series 3.Estimated the importance (variance) of SLV over different frequency bands and associated atmospheric processes 4.Computed present and future SLV climatology and linear trends. 5.Assessed a difference between frequency bands, present climate and scenarios, and sub-basins

4. The model Type: barotropic Domain: Mediterranean + a bite of Atlantic Resolution: 1/4 o 1/6 o, 8660 grid nodes Resolution: 1/4 o x 1/6 o, 8660 grid nodes Forcing: wind and air pressure Hindcast run: ARPEGE dynamical downscalling of ERA40, 1958-2001 Climate runs: Control (1950-2000) + SRES B1, A1B, A2, ARPEGE-v3 RegCM (2000-2100)

5. Hindcast model run has been validated over long-term tide gauge records, separately for each frequency band. Verification and reliability of the model results Good :) hm :(

6. Verification and reliability of the model results Control model run has been validated over hindcast model run, separately for each frequency band. Also done by Jorda et al. (GPC, in press) on reproduction of overall seasonal cycle, intra- and inter-annual variability. Relative difference in energy between control and hindcast model runs

7. Present climate SLV values (hindcast)

8. Present climate SLV trends (hindcast) Trends are mostly insignificant, although negative in average.

9. Present climate SLV trends (hindcast) Sporadically one may find significant negative trends over small areas within the domain.

10. Future climate SLV trends (75p) 1-3 d Trends are significantly negative!!!

11. Future climate SLV trends (99p) Less negative extreme SLV trends.

12. Future climate SLV trends (spatial, seasonal)

13. Conclusions and perspectives Mediterranean ocean climate model reproduced well the 3- 100-day SLV, and not so good the 1-3-day SLV – further downscalling of atmospheric CM to capture properly local temporal and spatial changes in forcing should be carried out. The largest SLV variance is occurring over the planetary frequency band (10-100 days), from 60 to 85% over the Mediterranean, emphasizing the importance of the associated processes in overall sea level extremes. Present Mediterranean SLV at periods between 1 and 100 days has mostly insignificant trends. Projected SLV trends are largely negative for A1B and A2 scenarios, and remained insignificant for B1 scenario. Negative trends are larger for the 1-3-day frequency band and during OND – implication to overall sea level extremes. A broadening in methodology (ensembles, fine analyses in frequency domain) is advised for future SLV studies.