|TITLE||SEA LEVEL AND MASS CHANGE IN MEDITERRANEAN AND BLACK SEA AND EXCHANGES AT THE STRAITS FROM SATELLITE-BASED OBSERVATIONS AND FROM MODELS|
|AUTHORS||Luciana Fenoglio (1)|Annarita Mariotti (2)|Gianmaria Sannino (3)|Benoit Meyssignac (4)|Adriana Carillo (3)|Maria Vittoria Struglia (3)|Michel Rixen (5)|
- Technische Universität Institute of Geodesy, Darmstadt, Germany
- National Oceanic and Atmospheric Administration, Office of Oceanic and Atmospheric Research, Silver Spring,, USA
- Italian Agency for Energy and Environment (ENEA), Roma , Italy
- LEGOS/CNES, Toulouse, France
- World Meteorological Organisation, Geneva, Switzerland
|ABSTRACT||The sea level and the mass-induced sea level variability in the Mediterranean and Black Sea are derived over 1993-2013 from altimetric and gravimetric (GRACE) satellite-based observations and from model data.
In the Mediterranen Sea the increase in sea level has a trend of 3.0 +/- 0.5 mm/yr and is dominated by the increase in the oceanic mass. The increase in sea level does not take place linearly but over short periods, each contributing 2-3 cm of sea level.
In the Black Seat the sea level and the mass-induced sea level variability is stronger than in the Mediterranean Sea, with strong increase from 2003 to 2005 followed by a decrease from 2006 to 2008.
The strait flows between the Mediterranean and Black Sea basins and with the Atlantic Ocean have been derived based on mass conservation using the mass-induced sea level variations, river runoff and precipitation minus evaporation. We find that at the Gibraltar strait the net inflow varies annually with amplitude of 52 +/- 10 x 10-3 Sv peaking end of September, while the inflow through the Bosporus strait displays annual amplitude of 13+/-3 x 10-3 Sv peaking in March. Most important, an increase of the Gibraltar net flow in 2002-2009 (3.4 +/- 0.8 x 10-3 Sv/yr) is detected, while the Bosporus net flow does not show significant trends over the analysed interval of time.
Also a similar analysis based on a sea level reconstruction over 1970-2009 points to an increase in net water flux at Gibraltar (0.8 +/- 0.2 mm/mo per year). We further consider results from a simulation using the PROTHEUS regional ocean-atmosphere coupled model, which extends over the longer interval 1960-2009. The simulated Gibraltar net water flow shows decadal variability during 1960-2009 including a net Gibraltar water flux decrease during 1960-1970 before the 1970-2009 increase.
The decadal variations in net evaporation at the sea-surface, such as the increase during 1970-2009, appear to drive the changes in net inflow at Gibraltar, while river runoff and net flow at the Bosporus Strait have a modulating effect. Mediterranean Sea mass changes are seen to be relatively small compared to water mass fluxes at the sea surface and do not show a long-term trend over 1970-2009. The Atlantic Multi-decadal Oscillation (AMO) and the North Atlantic Oscillation (NAO) are relevant indirect influences on net water flux at Gibraltar via their influence on regional evaporation, precipitation and runoff.|