Study of the uncertainties of Mediterranean Sea Climate Monitoring and Projections

Zusammenfassung

Introduction: The main goal of the present thesis is the characterization of the uncertainties of the Mediterranean Sea observational and simulation products in order to capture climate variability. Contents: Firstly, the capabilities of five marine observational networks to capture temperature and salinity evolution for the last decades of the 20th Century and for the whole 21st Century, as well as the characterization of other local processes such as the deep water formation rate in the western basin, have been tested. Results point out that temperature and salinity annual basin averages and long term trends are properly captured by all networks. Conversely, deep water formation rate in the western basin and other regional processes are largely over or underestimated by all networks. Secondly, the uncertainties of an ensemble of regional climate simulation hindcasts, spanning for the last decades of the 20th century, have been studied. Specifically, we quantified and analyzed the uncertainties linked to the model reproduction of a climatic key process such as the redistribution of heat and salt within the basin. From the characterization of those uncertainties, it has been pointed out that the spread between models is much larger than the ensemble average for the vertical salt transfer and for the heat transfer between 0-150 m and 150-600 m. At lower layers there is a set of models showing a good agreement between them, while others are not correlated with any other model. The mechanisms behind the ensemble spread are not straightforward. Finally, we explored the reliability of uncertainty estimations in climate simulations when the number of available