Project 1: Climate modelling
The primary method to estimate future climate conditions on Earth is to employ a numerical model of the climate system and to integrate this model forwards in time, employing a specified concentration of radiatively active gases and solar forcing. In order to accurately simulate the evolution of the climate system, a model that describes all the main interacting components of the climate system is required. Traditionally, these have been coupled, global atmosphere-ocean-land-sea ice models (GCMs). Within the Mistra-SWECIA project we employ and will further develop the EC-Earth GCM, in order to provide future Global Climate Simulations for a range of greenhouse gas emission scenarios. Mistra-SWECIA scientists working on the development of EC-Earth, will do so within the international EC-Earth consortium, which is developing the EC-Earth system for application in both decadal climate prediction and as an Earth System Model (ESM). More details on the EC-Earth model can be found in the descriptions of models used in project 1.Due to their computational cost and need for global coverage, GCMs are typically of relatively low resolution (e.g. 150-300 km per grid-box). In order to simulate the climate of a given region with increased detail, a widely employed technique is to embed a high-resolution, Regional Climate Model (RCM) covering a limited-area domain, within a GCM. In this set-up the RCM receives time-evolving, lateral boundary conditions from a GCM and then simulates the evolution of the local climate at high-resolution, consistent with the large scale climate as defined by the GCM Lateral Boundary Conditions. RCMs enable low-resolution information from GCMs to be consistently downscaled to an order of magnitude higher spatial resolution (typically 25 km per grid square today) enabling more efficient use of simulated climate information within climate impact and adaptation studies.
In Mistra-SWECIA we employ a number of configurations of the Rossby Centre Regional Climate Model:
- RCA; Atmosphere-Land RCM
- RCAO; a coupled Regional Ocean-Atmosphere-Sea ice-Land model for the Nordic Baltic Sea region and
- RCA-GUESS; a coupled Regional Ocean-Atmosphere-Sea ice-land-dynamic vegetation model. These models are all used to simulate high-resolution climate conditions over the Nordic region, in order to support impact and adaptation projects within other Mistra-SWECIA projects.
The resolution of the RCA model is limited to around 5 km per grid square, due to the model employing only hydrostatic dynamics. On the longer term, Mistra-SWECIA aims to provide regional climate simulations at resolutions higher than 5km. To achieve this goal, Mistra-SWECIA scientists have begun developing the HARMONIE Regional Numerical Weather Prediction (NWP) Model, for application as a Regional Climate Model. HARMONIE is a new NWP model specifically developed for application at 1-4 km resolution and has recently started being used in quasi-operational mode at SMHI. Collaboration with the international HARMONIE group will ensue over the coming years to further develop this model for application on climate timescales.
EMICs (Earth-System Models of Intermediate Complexity) describe most of the processes present in GCMs, but in a simpler form and with lower resolution. This makes EMIC much cheaper and easier to run, and allows a larger number of simulations to be made. In Mistra-SWECIA we use the Planet simulator, and will investigate whether it suitable for coupling to the economy models developed in Project 2. This requires that the EMIC is able to model both the average and the variability of temperature and precipitation, since climate variability is essential for the economic impact.
>>Climate models used in project 1
