Updated climate model opens new doors

After several years’ work, SMHI’s high-resolution regional climate model has been updated to a new version. The new solutions now make it possible to project detailed climate scenarios around the world.

For almost 15 years, SMHI’s climate scientists have been working to produce high-resolution models for projecting climate development. The fourth generation, RCA4, has now been produced, and the new version has been updated with modern programming and better land property descriptions.

“The advanced computer projections for climate scenarios will require modern coding in the programs, and we have worked concertedly to achieve this,” says Marco Kupiainen, a mathematician at SMHI’s climate research unit, Rossby Centre.

“It is also now far easier for our Swedish and international science partners to use the climate model.”

Scenarios for selected parts of the world

One crucial reason for a new model version has been the need to produce detailed climate scenarios for selected parts of the world, perhaps primarily developing countries. The previous version only dealt with scenarios in Europe. The solution lies in collecting descriptions of land characteristics in different geographical areas, information which can now be updated via global databases. These are factors that considerably affect the climate, and they include topography and vegetation.

“Our climate research is contributing to several international projects, where RCA4 will be an important tool. We have already used a development version to make projections for Africa and South America, with good results,” says climate scientist Patrick Samuelsson.

RCA4 will be an important cornerstone of the CORDEX project, in which various countries are co-operating to develop high-resolution climate projections for large parts of the world. The new projections will be useable within these countries, but will also provide foundation data for the next assessment from the UN Intergovernmental Panel on Climate Change.

RCA4 will also increase opportunities for linking land and atmospheric projections with projections for freshwater catchments, oceans and ice.

International co-operation

RCA4 is, as well as earlier versions, built upon the development of the international HIRLAM-programme. HIRLAM (HIgh Resolution Limited Area Model) is a research cooperation of European meteorological institutes. The aim of the HIRLAM programme is to develop and maintain a numerical short-range weather forecasting system for operational use by the participating meteorological institutes.