Regional Earth System Modeling
A number of regional climate model (RCM) systems have been developed during the last two decades in order to downscale the output from large scale global climate model simulations and produce fine scale regional climate change information useful for impact assessment and adaptation studies (e.g. Giorgi 2006a).
To date most RCMs have been essentially composed by an atmospheric component coupled to a land surface scheme and driven over ocean areas by prescribed sea surface temperature (SST). Although such a RCM can be sufficient for many applications, there are cases in which the fine scale feedbacks associated with air-sea interactions can substantially influence the spatial and temporal structure of regional climates.
The development of a Regional Earth System Model has been one of the main objective of the Regional climate variability research area of ENEA. Our main focus is the Mediterranean climate variability, together with the simulations of the African climate.
- Modelling the Mediterranean coupled system
- Mediterranean ocean variability
- Land-surface atmosphere interaction
- River modeling
- Impact modeling
- African climate
Modelling the Mediterranean coupled system
We developed an atmosphere-ocean regional climate model (AORCM) for the Mediterranean basin, called the PROTHEUS system, composed by the regional climate model RegCM3 as the atmospheric component and by a regional configuration of the MITgcm model as the oceanic component. The model is applied to an area encompassing the Mediterranean Sea and compared to a stand-alone version of its atmospheric component. An assessment of the model performances is done by using available observational datasets.
Despite a persistent bias, the PROTHEUS system is able to capture the inter-annual variability of seasonal SST and also the fine scale spatio-temporal evolution of observed SST anomalies, with spatial correlation as high as 0.7 during summer. The close inspection of a 10-day strong wind event during the summer of 2000 proves the capability of the PROTHEUS system to correctly describe the daily evolution of SST under strong air-sea interaction conditions. As a consequence of the model's skill in reproducing observed SST and wind fields, we expect a reliable estimation of air-sea fluxes. The model skill in reproducing climatological land surface fields is in line with that of state of the art regional climate models.
This activity is carried out in collaboration with ICTP
Within the CIRCE-EU project, we performed regional climate scenarios for the Mediterranean region.
Figure. SST anomalies (degrees C) for 09/07/2000 in CPL scale observations.
Figure. SST anomalies (degrees C) for 09/07/2000 in fine scale observations.
Mediterranean ocean variability
The oceanic component of the PROTHEUS system is firstly validated comparing the sea level variability reproduced by the model with altimeter data and then used to study the interannual variability of the Mediterranean Sea and to extrapolate future behavior using the A1B scenario of IPCC.
Please note that this work is in progress.
The validation with data shows that the fully coupled model (C4, panell upper right on the figure below) bette represents the 'strange' sea level behavio observed between 1993 and 1998 in the Eastern Mediterranean. Probably due to the cooncomitant Eastern Mediterranean Transient, the sea level in the 90's in the EM shown a complicate behavior with apparent oscillation of the sea level height both in space and time.
Figure. Sea level trend observed between 1993 and 1998 in the EM from AVISO data (upper left panel) fully copled experiment (upper right panel), oceanic stand-alone experiment (lower left panel) and partly coupled experiment (lower right panel, this experiment is equal to C4 except the interactive river run off scheme)
Land-surface atmosphere interaction
We investigate the impact of land cover changes on regional climate over the Euro Mediterranean area. Land use and Land Cover Changes (LCC) affect the local, regional and global climate system thro