Abstract
This study evaluates the Mediterranean Sea heat budget components from a set of forced and coupled simulations performed in the frame of the Med-CORDEX project. The simulations use regional climate system models (RCSMs) dedicated to the Mediterranean area and driven by the ERA40/ERA-Interim reanalyses. The study focuses on the period 1980–2010. Interannual variations of the average net heat flux at the sea surface are consistent among models but the spread in the mean values is large (from −4.8 to +2.2 Wm−2) with the coupled models showing the lowest heat loss from the sea. For the heat flux at the Strait of Gibraltar both interannual variations and mean values show a large intermodel spread. The basin average temperature shows positive trends with highest values in the coupled models; it also shows interannual variations that are in good agreement with observations. The heat content rate is calculated based on the derivative of the average temperature and is found to be significantly correlated for most models with the net heat flux at the sea surface (average correlation ~0.5) but not with the net heat flux through the Strait of Gibraltar (average correlation ~0.2), suggesting that in the considered RCSMs the interannual variability of the heat content rate is mainly driven by the surface heat fluxes. The resemblance between the simulated and observed heat content rates is stronger in the forced models than in the coupled ones. This is explained by the stronger constraint applied to the forced models by the use of the surface temperature relaxation to observations. The temperature of the outflowing water through the Strait of Gibraltar shows positive and significant trends, also higher in the coupled models. It is suggested that the Mediterranean Sea warming found in most models and in particular in the coupled ones, induces a change of the hydrographic conditions that affects the Strait of Gibraltar.
Highlights
The Mediterranean Sea is a semi-enclosed basin connected to the Atlantic Ocean at the Strait of Gibraltar
The heat budget components of the Mediterranean Sea are studied based on a set of numerical simulations performed using the regional climate system models (RCSMs) which include both forced and coupled models
The first ones are Mediterranean Sea models forced by downscaled versions of the ERA40/ERA-Interim reanalyses
Summary
The increase is deduced from an unbalance between the net heat flux at the Strait of Gibraltar (based on a combination of climatological data sets and in situ measurements), and a long-term average of the net heat flux at the sea surface. SanchezGomez et al (2011) compared the simulated net heat fluxes at the sea surface and obtained an ensemble average value of −9 Wm−2 but the spread was large (from −40 to +21 Wm−2). In this paper we use the results from this new data set to characterize the mean values and long term changes of the heat budget components of the Mediterranean Sea. The results are compared to available observations and to previous simulations.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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
