The control integration, in which the atmospheric forcing is kept constant, simulates a period over 1000 years in length. Control experiment (CTL): The IPCC Data Distribution Centre (DDC) distributes data of a 240-year period according to the length of the climate change experiments (the greenhouse gas and the greenhoue gas plus sulphate aerosol forcing runs) available from Hadley Centre. The climatology constructed from this 240-year CTL run serves as a reference for the time-dependent forcing experiments GG and GS scenarios. These data represent monthly averaged surface values of selected variables for the IPCC-Data Distribution Centre. (see also https://www.ipcc-data.org/ )