D6.1 Climate Model Data for Europe
This report documents the datasets published as Deliverable D6.1 “Climate model data forEurope, bias-corrected when necessary, for CCII-T1 calculation. Documented dataset”, where“CCII-T1” stands for “Tier 1 Climate ChangeClimate Change
Climate change refers to a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use. Note that the United Nations Framework Convention on Climate Change (UNFCCC), in its Article 1, defines climate change as: 'a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods'. The UNFCCC thus makes a distinction between climate change attributable to human activities altering the atmospheric composition, and climate variability attributa Impact Indicators”. The focus is on bias corrected data at three different spatial resolutions:
i) global climate model (GCM) data interpolated to a common 2° × 2° grid,
ii) regional climate model data (RCM) at the Euro-Cordex 0.44° × 0.44° (~ 50 km × 50km) grid, and
iii) RCM data at the Euro-Cordex 0.11° × 0.11° (~ 12 km × 12 km) grid.
Alternative bias correction methods have been used by the groups contributing to this deliverable. The methods are described in detail and sample results are presented. They are substantially dependent on long high-quality daily reference datasets, spanning at least 20 years. For Europe well established datasets are available for temperature (daily mean, minimum and maximum) and precipitation. Hence, the report focusses on these variables. All methods produce a substantial reduction of the bias during the reference period. The bias reduction is one order of magnitude, and typically more successful for temperature than for precipitation fields. As expected, different methods do not result in exactly the same corrected data.
The bias corrected climate model datasets are currently available through the CLIPC webportal and will eventually become available through the Earth System Grid Federation (ESGF) web portals. The latter host the corresponding archive of the non-bias-corrected (“raw”) climate model data. The datasets published as CLIPC Deliverable D6.1 are the first based on multi-method bias correction of published Euro-Cordex RCM data at two spatial resolutions, and complemented by bias corrected GCM data.
These datasets are publicly available and can be further explored for many and diverse purposes. A straightforward application within CLIPC consists of deriving the Tier 1 Climate Change Impact Indicators (CCII-T1) based on daily precipitation and 2m air temperature provided by the RCMs.
The use of multiple bias correction methods enables a deeper analysis of the robustness and uncertainties associated with bias correction. As a consequence, the bias correction task within CLIPC WP6 provides a catalytic contribution to the Bias Correction IntercomparisonProject (BCIP) across a number of EU funded research projects.
Finally, CLIPC WP6 aims to explore the possibility of using the remotely sensed data as reference datasets to allow bias correction of a larger selection of model output variables where relevant reference datasets currently are lacking.