Abstract
Abstract. The French research community in the Mediterranean Sea modeling and the French operational ocean forecasting center Mercator Océan have gathered their skill and expertise in physical oceanography, ocean modeling, atmospheric forcings and data assimilation to carry out a MEDiterranean sea ReanalYsiS (MEDRYS) at high resolution for the period 1992–2013. The ocean model used is NEMOMED12, a Mediterranean configuration of NEMO with a 1∕12° ( ∼ 7 km) horizontal resolution and 75 vertical z levels with partial steps. At the surface, it is forced by a new atmospheric-forcing data set (ALDERA), coming from a dynamical downscaling of the ERA-Interim atmospheric reanalysis by the regional climate model ALADIN-Climate with a 12 km horizontal and 3 h temporal resolutions. This configuration is used to carry a 34-year hindcast simulation over the period 1979–2013 (NM12-FREE), which is the initial state of the reanalysis in October 1992. MEDRYS uses the existing Mercator Océan data assimilation system SAM2 that is based on a reduced-order Kalman filter with a three-dimensional (3-D) multivariate modal decomposition of the forecast error. Altimeter data, satellite sea surface temperature (SST) and temperature and salinity vertical profiles are jointly assimilated. This paper describes the configuration we used to perform MEDRYS. We then validate the skills of the data assimilation system. It is shown that the data assimilation restores a good average temperature and salinity at intermediate layers compared to the hindcast. No particular biases are identified in the bottom layers. However, the reanalysis shows slight positive biases of 0.02 psu and 0.15 °C above 150 m depth. In the validation stage, it is also shown that the assimilation allows one to better reproduce water, heat and salt transports through the Strait of Gibraltar. Finally, the ability of the reanalysis to represent the sea surface high-frequency variability is shown.
Highlights
The Mediterranean Sea is a semi-enclosed sea located between 5.5◦ W and 36◦ E and between 30 and 46◦ N
In the same way of these previous studies and in order to enhance the diversity of the Mediterranean Sea reanalyses, we present in this study another reanalysis of the Mediterranean circulation, MEDiterranean sea ReanalYsiS (MEDRYS), performed with different tools and covering the altimetry 1992–2013 period
This study describes the configuration and the quality of the high-resolution reanalysis MEDRYS and its companion hindcast NM12-FREE, for the Mediterranean Sea over the period 1992–2013
Summary
The Mediterranean Sea is a semi-enclosed sea located between 5.5◦ W and 36◦ E and between 30 and 46◦ N. The first regional Mediterranean reanalyses have been recently produced over the 1985–2007 period by Adani et al (2011), using a reduced-order optimal interpolation and a 3-D variational scheme Their OPA ocean model (Océan PArallélisé, Madec et al 1997) on a 1/16◦ regular horizontal grid (Tonani et al, 2008) is forced by daily atmospheric fields from the European Center Medium-Range Weather Forecast (ECMWF) with bulk parameterizations and a monthly precipitation climatology. Even if we cannot overcome other homogeneity issues resulting from the coverage of the observing network (applying in both MEDRYS and ALDERA), we pay a special attention to the consistency of the atmospheric forcing (same resolution, same model physics) in order to reduce as much as possible the sources of inhomogeneity in MEDRYS This reanalysis contributes to better describe the interannual to decadal variability of the Mediterranean circulation and trends.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
