Comparison of Mediterranean Sea levels fields for the period 1961 - 2000 as given 1 by a data reconstruction and a 3 D model

Comparison of Mediterranean Sea levels fields for the period 1961-2000 as given 1 by a data reconstruction and a 3D model. 2 3 F. M. Calafat , D. Gomis , M. Marcos a 4 5 a IMEDEA (UIB-CSIC), Miquel Marques, 21, Esporles 07190, Mallorca, Baleares, Spain 6 7 Corresponding author. 8 E-mail address: [email protected] 9 Telephone number: +34 971610983 10 Fax number: +34 971611761 11 12 13 14 Abstract. Two Mediterranean Sea level distributions spanning the last decades are 15 examined. The first one is a reconstruction of sea level obtained by a reduced-space 16 optimal interpolation applied to tide gauge and altimetry data. The second distribution is 17 obtained from a 3D (baroclinic) regional circulation model. None of the two 18 representations includes the mechanical atmospheric forcing. Results are presented for 19 two different periods: 1993-2000 (for which altimetry data are available) and 1961-2000 20 (the longest period common to both distributions). 21 The first period is examined as a test period for the model, since the reconstruction is 22 very similar to altimetry observations. The modelled sea level is in fair agreement with 23 the reconstruction in the Western Mediterranean and in the Aegean Sea (except in the 24 early nineties), but in the Ionian Sea the model departs from observations. For the whole 25 period 1961-2000 the main feature is a marked positive trend in the Ionian Sea (up to 26 1.8 mm yr), observed both in the reconstruction and in the model. Also the 27 distribution of positive trends in the Western Mediterranean (mean value of 1.1 mm 28 yr) and the smaller trends in the Aegean Sea (0.5 mm yr) are similar in the 29 reconstruction and in the model, despite the first implicitly accounts for sea level 30 variations due to remote sources such as ice melting and the second does not. The 31 interannual sea level variability associated with key regional events such as the Eastern 32 Mediterranean Transient is apparently captured by the reconstruction but not by the 33 model (at least in its present configuration). Hence, the reconstruction can be envisaged 34 as a useful tool to validate further long-term numerical simulations in the region. 35 36 37 38 39 40 41 42 43 44 45 46