The fields will be used for the analyses. We will also generate impact-relevant indices such as growing degree days, frost days, and dry spells.The third part of the project provides subdaily high-resolution fields using data assimilation and dy-namical donwscaling. We will use Version 3 of the „Twentieth Century Reanalysis“ (20CR), which provides global weather data back to 1804. We will dynamically downscale 20CRv3 for periods in the early 19th century (including the warm summers of the 1800s and the “Year Without a Summer” of 1816) and will test 4D-Var assimilation within WRF to assimilate additional observations. The daily data from the three project parts, combined with monthly reconstructions and climate model simulations, will be used to study European climate variability of the past 400 years. We will focus on decadal periods of warm and dry summers, which will be analysed with respect to links to the (sub-)tropical circulation (monsoons, tropical belt) using other reconstructions and models. We will focus on the sequence of warm summers around 1730, 1780, and 1800 and will compare them with the 1940s summers. A second focus are cold winters, such as 1683/4, 1708/9 and 1829/30, which will be analysed with respect to a meridionalisation of atmospheric circulation and relations to sea-surface temperatures or snow cover in Eurasia. Detailed studies will also be performed on the impcats of the volcanic eruptions of Serua (1693), Laki (1783/4), Tambora (1815) and others. Our data will yield new insights into the workings of the climate systems and bridge the gap from weather to climate.