Nikinmaa assessment of land - cover data for land - surface modelling in regional climate studies

We studied the land-cover data used by the regional climate model REMO and the land surface model JSBACH, for Finland and surrounding areas. To date, the land-cover data determining REMO’s surface parameterisations have originated from the Global Ecosystem classification of the Global Land Cover Characteristics (GLCC-GEC) database. The same database has also been used as basis for prescribed plant functional type distribution with JSBACH. We showed that the GLCC-GEC does not represent the Finnish landscape particularly well, and there are large errors in the land cover type distributions. Furthermore, we have inspected the values of the land surface parameters forest ratio and leaf area index, which were assigned to land-cover types, and found them to typically be too large for Finland. Different revised land-cover data sets were created using GlobCover and different versions of Corine Land Cover (CLC) classifications. The benefits of the new land-cover data sets were much more spatial detail and thematic content which corresponded better to the Finnish environment, unlike in the GLCC-GEC. For example, there are wetlands and they are correctly located. Although no definite reference exists to assess the qualification of the land-cover data in the light of the model results, modelling benefits from the use of land-cover data that is more spatially accurate and recent. Even though regionally the differences are not great, at a more local level they become substantial.