Ocean Science www.ocean-sci.net 1812-0784 1812-0792 3 1 2007 10.5194/os-3-149-2007 http://www.ocean-sci.net/3/149/2007/ http://www.ocean-sci.net/3/149/2007/os-3-149-2007.html http://www.ocean-sci.net/3/149/2007/os-3-149-2007.pdf 149 157 2007-03-08 Daily oceanographic analyses by Mediterranean Forecasting System at the basin scale S. Dobricic dobricic@bo.ingv.it N. Pinardi M. Adani M. Tonani C. Fratianni A. Bonazzi V. Fernandez Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy Centro Interdipartimentale di Ricerche per le Scienze Ambientali, Ravenna, Italy This study presents the upgrade of the Optimal Interpolation scheme used in the basin scale assimilation scheme of the Mediterranean Forecasting System. The modifications include a daily analysis cycle, the assimilation of ARGO float profiles, the implementation of the geostrophic balance in the background error covariance matrix and the initialisation of the analyses. A series of numerical experiments showed that each modification had a positive impact on the accuracy of the analyses: The daily cycle improved the representation of the processes with the temporal variability shorter than a week, the assimilation of ARGO floats profiles significantly improved the salinity analyses quality, the geostrophically balanced background error covariances improved the accuracy of the surface elevation analyses, and the initialisation removed the barotropic adjustment in the forecast first time steps starting from the analysis. Buongiorno Nardelli, B., Larnicol, G., D'Acunzo, E., Santoleri, R., Marullo, S., and Le Traon, P. Y.: Near Real Time SLA and SST products during 2-years of MFS pilot project: processing, analysis of the variability and of the coupled patterns, Ann. Geophys., 21, 103–121, 2003. Castellari, S., Pinardi, N., and Leaman, K. D.: A model study of air-sea interactions in the Mediterranean Sea, J. Mar. Syst., 18, 89–114, 1998. Daley, R.: Atmospheric data analysis. Cambridge atmospheric and space science series,Cambridge University Press, ISBN 0-521-38215-7, 1991. De Mey, P. and Benkiran, M.: A multivariate reduced-order optimal interpolation method and its application to the Mediterranean basin-scale circulation, Ocean Forecasting, edited by: Pinardi, N. and Woods, J., Springer Verlag, 281–306, 2002. Demirov, E. and Pinardi, N.,: Simulation of the Mediterranean Sea circulation from 1979 to 1993. Part I: The interannual variability, J. Mar. Syst., 33–34, 23–50, 2002. Demirov, E., Pinardi, N., Fratianni, C., Tonani, M., Giacomelli, L., and De Mey, P.: Assimilation scheme in the Mediterranean forecasting system: operational implementation, Ann. Geophys., 21, 189–204, 2003. Dobricic, S., Pinardi, N., Adani, M., Bonazzi, A., Fratianni, C., and Tonani, M.: Mediterranean Forecasting System: An improved assimilation scheme for sea-level anomaly and its validation, Q. J. R.. Meteorol. Soc., 131, 3627–3642, 2005. Le Traon, P. Y., Nadal, F., and Ducet, N: An improved mapping method of multisatellite altimeter data, J. Atmos. Oceanic Technol., 15, 522–533, 2003. Manzella, G., Cardin, V., Cruzado, A., Fusco, G., Gacic, M., Galli, C., Gasparini, G., Gervais, T., Kovacevic, V., Millot, C., Petit DeLa Villeon, L., Spaggiari, G., Tonani, M., Tziavos, C., Velasquez, Z., Walne, A., Zervakis, V., and Zodiatis, G.: EU-sponsored effort improves monitoring of circulation variability in the Mediterranean, EOS Transactions, American Geophysical Union, 82, 497–504, 2001. The MEDAR Group: MEDAR/MEDATLAS 1998-2001 Mediterranean and Black Sea database of temperature, salinity and bio-chemical parameters and climatological atlas (4 CDRoms), Internet server http://www.ifremer.fr/sismer/program/medarIFREMER/TMSI/IDM/SISMER Ed., Centre de Brest, 2002. Pinardi, N., Rosati, A., and Pacanowski, R. C.: The sea surface pressure formulation of rigid lid models. Implications for altimetric data assimilation studies, J. Mar. Syst., 6, 109–119, 1995. Pinardi, N., Allen, I., Demirov, E., De Mey, P., Korres, G., Lascaratos, A., Le Traon, P.-Y., Maillard, C., Manzella, G., and Tziavos, C.: The Mediterranean ocean forecasting system: first phase of implementation (1998–2001), Ann. Geophys., 21, 3–20, 2003. Rio, M. E., Poulain, P.-M., Pasqual, A., Mauri, E., Larnicol, G., and Santoleri, L.,: A mean dynamic topography of the Mediterranean Sea computer from the altimetric data and in situ measurements, J. Mar. Sys., 65, 484–508, 2007. Roullet, G. and Madec, G.: Salt conservation, free surface, and varying levels: a new formulation for ocean general circulation models, J. Geophys. Res., 105, 23 927–23 942, 2000. Talagrand, O.: On the damping of high-frequency motions in four-dimensional assimilation of meteorological data, J. Atmos. Sci., 29, 1571–1574, 1972.