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Study of the impact of a new Drag Coefficient parameterization on the forecasting skill of an Ocean Model in the Aegean and Levantine Seas

Vassilis Kostopoulos, Eurydice Chrisagi, Sarantis Sofianos, Konstantinos Helmis


The aim of this work is to study the response of an ocean circulation model in the Eastern Mediterranean Sea, using a new drag coefficient formula based on observations at this area. Thirty twin simulation experiments of 5-days, using two different drag coefficient parameterizations were carried out by the Aegean-Levantine Eddy Resolving Model in a forecasting mode, covering all seasons and different wind field patterns for the year 2013. The new formula’s forcing is based on measurements over the Aegean Sea while the second one is currently used by the model. The results show that the sea surface circulation was enhanced using the new parameterization giving wind stress values greater about 30%. The forecasting skill of the model was tested by comparing the daily sea surface temperature averaged estimations using the two formulas, with satellite observation records. Significant differences were found between the two formula’s forecasts, both in space and in time, over the Aegean Sea and over the areas of the Levantine basin. Improved SST forecasts were found during spring over the Aegean Sea, while during autumn and winter, the differences were almost negligible. At summer, the bias was increased with undesired effects regarding SST forecasts, close to the coastal regions of the Eastern Mediterranean Sea that favor coastal upwelling. 

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Burillo IA, Caniaux G, Gavart M, De Mey P, Baraille R. Assessing ocean-model sensitivity to wind forcing uncertainties. Geophys Res Lett. 2002 Sep; 29(18):51-4.

Rosati A, Miyakoda K. A general circulation model for upper ocean simulation. J Phys Oceanogr. 1988 May; 18:1601-26.

Fairall CW, Bradley EF, Hare JE, Grachev AA, Edson JB. Bulk Parameterization of Air-Sea Fluxes. Updates and verification for the COARE Algorithm. J Climate. 2003 May; 16:571-91.

Korres G, Lascaratos A. A one-way nested eddy resolving model of the Aegean and Levantine basins: implementation and climatological runs. Ann Geophys. 2002 Jan; 21(1):205-20.

Smith SD. Wind Stress and Heat Flux over the Ocean in Gale Force Winds. J Phys Oceanogr. 1980 May; 10:709-26.

Paulson CA. The Mathematical Representation of Wind Speed and Temperature Profiles in the Unstable Atmospheric Surface Layer. J Appl Meteor. 1970 Dec; 9:857-61.

Drennan WM, Graber HC, Hauser D, Quentin C. On the wave age dependence of wind stress over pure wind seas. J Geophys Res. 2003 Mar; 108(C3):8062.

Kostopoulos VE, Helmis CG. Flux measurements in the surface marine Atmospheric Boundary Layer over the Aegean Sea. Sci Total Environ. 2014 Jul; 494-495: 166-76.

Sofianos S, Skliris N, Vervatis V, Olson D, Kourafalou V, Lascaratos A, et al. On the Forcing Mechanisms of the Aegean Sea Surface Circulation. European Geosciences Union General Assembly; 2015 Apr 12-17; Vienna (AT). 2015.Geophys Res Abstr 17

Hellerman S, Rosenstein M. Normal monthly wind stress over the World Ocean with error estimates. J Phys Oceanogr. 1983 Mar; 13:1093-104.

Skliris N, Sofianos S, Gkanasos A, Axaopoulos P, Mantziafou A, Vervatis V. Long-term sea surface temperature variability in the Aegean Sea. Adv Limnog Oceanogr 2011 Nov; 2(2):125-39.

Tzali M, Sofianos S, Mantziafou A, Skliris N. Modelling the impact of Black Sea water inflow on the North Aegean Sea hydrodynamics. Ocean Dynam. 2010 Jun; 60(3):585-96.

Rizou D, Flocas H, Bartzokas A, Helmis CG. in: Lekkas TD, editor. On the link between Indian summer monsoon and the Etesian pattern over the Aegean Sea. CEST 2013: Proceedings of the 13th International Conference on Environmental Science and Technology; 2013 Sep 5-7; Athens (GR). Univesity of the Aegean. 2013. Available from:

Sofianos S, Johns W, Lascaratos A, Murray S, Olson D, Theocharis A. Draft Report of the Aegean Sea Workshop. Proceedings of the Aegean Sea Workshop; 2002 Oct 8-10; Rhodes (GR). 2002. Available from:

Karlsson S. The Applicability of Wind Profile Formulas to an Urban-Rural Interface Site. Bound-Lay Meteorol. 1986 Mar; 34:333-55.

Korres G, Lascaratos A, Sofianos S, Kallos G.. The ALERMO ocean circulation forecast system, 3rd EuroGOOS Conference; 2002 Dec; Athens (GR).

Tonani M, Teruzzi A, Korres G, Pinardi N, Crise A, Adani M et al. 2014. The Mediterranean Monitoring and Forecasting Centre, a component of the MyOcean system. Proceedings of the Sixth International Conference on EuroGOOS; 2011 Oct 4-6. Sopot (PL). Eurogoos Publication. 2011.

Dombrowsky E, Bertino L, Brassington GB, Chassignet EP, Davidson F, Hurlburt et al. GODAE Systems in operation. Oceanography. 2009;22(3):83-95.

Kallos G. The Regional weather forecasting system SKIRON. Proceedings, Symposium on Regional Weather Prediction on Parallel Computer Environments; 1997 Oct 15-17; Athens (GR). 1997.

Madec G. NEMO reference manual, ocean dynamics component: NEMO-OPA. Preliminary version. Institut Pierre-Simon Laplace (FR). 2008. 399p. Report No.: 27. ISSN No.: 1288-1619. Available from:

Nardelli B, Tronconi C, Pisano A, Santoleri R. High and Ultra-High resolution processing of satellite Sea Surface Temperature data over Southern European Seas in the framework of MyOcean project. Rem Sens Env. 2013 Oct; 129:1-16.

Kara BA, Helber RW, Boyer TP, Elsner JB. Mixed layer depth in the Aegean, Marmara, Black and Azov Seas: Part I: General features. J Marine Syst. 2009 Nov; 78:169-80.

Chen D, Busalacchi AJ, Rothstein LM. The roles of vertical mixing, solarradiation, and wind stress in a model simulation of the sea-surface temperature seasonal cycle in the tropical Pacific Ocean. J Geophys Res. 1994 Oct; 99(20):345-59.

Small RJ, deSzoeke SP, Xie SP, O’Neill L, Seo H, Song Q et al. Air-sea interaction over ocean fronts and eddies. Dyn Atmos Oceans. 2008 Jul; 45(3-4):274-319.


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