EC-EARTH EC-EARTH is an Earth System Model (ESM) that is developed by a consortium of European Weather Services and university groups. It is based on the seasonal prediction system of ECMWF and currently consists of a model for the atmosphere and a model for the ocean that communicate with each other through the Oasis coupler. Additional modules (chemistry, vegetation) are under development. The atmospheric component of the coupled model is the ECMWF IFS (Integrated Forecast System) model version 31r1. There are 62 levels in the vertical, with a model top at ~5hPa. The dynamical part of the model uses a spectral transform approach, with a present horizontal resolution of TL159 (~0.75 degrees).
All of the model physical parameterization schemes (including clouds, rain, turbulence and land surface processes) are calculated on a reduced N80 gaussian grid, which corresponds to a 1.125 degrees spacing. The atmospheric model uses a two time-level semi-Lagrangian scheme for its dynamics with a 1-hour time step.
The IFS has a comprehensive treatment of physical processes within the atmosphere. The radiative transfer uses RRTM in the long wave, discrete spectral intervals in the shortwave, and has an advanced treatment of the interaction with clouds. Convection is based on a mass flux scheme, and treats shallow, mid-level and deep convection. Cloud plumes are represented within the convection scheme by a bulk model and include updraft and downdraft mass fluxes.
Momentum transport by convective circulations is also included. There are parameterizations of the boundary layer and of gravity wave drag. The land surface includes 4 sub-surface soil levels with prognostic moisture and temperature, as well as the vegetation canopy.
The ocean component is NEMO (Nucleus for European Modelling of the Ocean), a primitive equation model adapted to regional and global ocean circulation problems. Prognostic variables are the three-dimensional velocity field, a linear or non-linear sea surface height, temperature and salinity.
In the horizontal direction, the model uses a curvilinear orthogonal grid with the North Pole shifted to Greenland. The nominal horizontal resolution is 2 degrees with refinement at the equator. The horizontal resolution will increase to 1 degree in future versions of EC-EARTH. In the vertical direction, a full or partial step z-coordinate, or s-coordinate, or a mixture of the two can be used. There are 31 levels in the vertical. The distribution of variables is a three-dimensional Arakawa C-type grid. Various physical choices are available to describe ocean physics, including TKE and KPP vertical physics. NEMO also includes the sea-ice model LIM. At present EC-EARTH uses version 2.3 of NEMO but an upgrade to version 3 is planned. The newer version will feature LIM3, a vastly improved version of the LIM sea-ice model that is better suited for climate modelling (including the treatment of salinity in brine pockets and multi-category ice).
RCA
RCA is the Rossby Centre Regional Atmospheric Climate Model (RCM). Over the past 5-10 years RCA has been applied extensively over Europe at a resolution of 50 km. In recent years, this resolution has been increased to 25 km, with plans to move this standard to ~12km in the coming few years. As a consequence of employing a limited-area domain, RCA requires the application of lateral boundary conditions (LBCs), whereby the inner RCM solution is forced by, and matched towards, the evolving climate as simulated by a GCM. LBCs are generally applied every six hours, with a linear time interpolation between these time points. In this manner, RCA is able to generate a high-resolution realization of the climate system, over a given region of interest, consistent with the evolution of the climate on larger scales as simulated by a forcing GCM which supplies the RCA lateral boundary conditions.
RCA employs a 2-time level semi-lagrangian, semi-implicit dynamical scheme, with typically 24 or 40 levels in the vertical. A full suite of physical parameterizations are employed that describe the main physical processes in the atmopshere (e.g land-surface processes, convection, turbulence, radiation transfer, cloud formation and condensation/precipitation). These parameterizations have been developed and evaluated for application in the resolution range 10-50 km. RCA can be integrated efficiently on a large number of parallel processors, enabling a large number of RCA simulations at a relatively low computational cost. RCA has been applied in numerous international comparison projects over both Europe and other regions of the globe (e.g. the Arctic, Africa,South America), consistently performing well in comparison to other international RCMs.
RCA has been coupled to the Rossby Centre Ocean Model (RCO), forming a coupled Regional Atmosphere-Ocean-Sea Ice model applicable either to the Baltic Sea or Arctic Ocean. In both cases a fully coupled regional climate, at high-resolution, can be simulated. RCA has also been coupled to an interactive, dynamic vegetation model, based on the LPJ (Lund-Potsdam-Jena) model, resulting in the model RCA-GUESS, which is able to interactively simulate the two-way coupling between climate and vegetation. This system has been successfully applied to simulating coupled climate-vegetation processes over Scandianvia and will be used in the future over the Arctic and South America.
A more detailed description of the RCA, RCO and RCAO coupled models, including a list of references for the model and associated parameterizations can be found at Rossby Centres website, under the respective model headings.
EMICs
EMICs (Earth-System Models of Intermediate Complexity) describe most of the processes implicit in comprehensive climate models, albeit in a simpler form. They explicitly simulate the interactions among several components of the climate system, including biogeochemical cycles, and at the same time they are simple enough to allow for long-term climate simulations. Similarly as comprehensive models, but in contrast to simple energy-balance models, the number of degrees of freedom of an EMIC exceeds the number of adjustable parameters by several orders of magnitude.
The EMIC used in Mistra-SWECIA is the Planet simulator, which has been developed at the University of Hamburg. It has a three-dimensional atmospheric model of similar kind as comprehensive models, but with lower resolution. The oceanic part is a mixed-layer model which describes the oceanic heat storage, but not the ocean circulation. It also has a thermodynamic ice model, and a biosphere model with dynamic vegetation. In Mistra-SWECIA the Planet simulator will be used together with economic models that simulate the economic development and the CO2 emissions.
