A Coupled modelling attempt of hydrodynamics and ecosystem of northern levantine basin

Aydoğdu, Ali
A three-dimensional ocean model, ROMS, has been utilized to simulate the hydrodynamics and the ecosystem dynamics of the Northern Levantine Basin circulation. The model is one-way nested inside a coarser resolution Mediterranean Sea eco-hydrodynamics model, forced with realistically updated surface and lateral fluxes of momentum, mass, heat and nutrients. Scenario runs representing present and future time-slices of 5 years each have been used to investigate sensitivity to climate in the near future. Other sensitivity tests depending on model parameters and options have been performed. It is revealed that the Asia Minor Current, dominating the basin circulation, divides the basin into the two basic regions of coastal and open sea characteristics. Although satisfactory results are reached for the general behaviour of the ecosystem, the model tends to overestimate the surface chlorophyll concentration. Sea surface patterns of variables predicted by the model are compared with satellite data indicate general agreement in the seasonal patterns. Based on the selected climate change scenario for 30-40 year difference of the time slices, rises of 0.33◦ C and 0.035 respectively in surface temperature and salinity are estimated in daily average properties. As a result, surface chlorophyll concentrations are increased by 8%. Moreover, significant changes in the periodicity of seasonal phytoplankton blooms are found. Results of the parameter and option sensitivity tests have revealed the need for better representation of surface fluxes and a careful tuning of the mixing achieved by the model, especially at the surface levels. Sensitivity runs also showed that the temperature and salinity at the surface were overestimated because of the need for better representation of the penetration of radiation in the surface waters. The results are promising, whereas there is need for further investigation of basic processes such as the Levantine Intermediate Water (LIW) formation.


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Citation Formats
A. Aydoğdu, “A Coupled modelling attempt of hydrodynamics and ecosystem of northern levantine basin,” M.S. - Master of Science, Middle East Technical University, 2012.