Three prominent Swiss series that reach further back than 1864 (Geneva, Basel, Gr. St. Bernard) have recently been digitised based on the original readings. However, there are several additional series, including two long series from Schaffhausen and Bern reaching back to the 18th century and several shorter series from the 18th and 19th centuries. Together, they could substantially extend the available information. In the proposed project we will:
(1) produce a systematic survey of pre-1864 Swiss meteorological data,
(2) digitise a large fraction of these data,
(3) perform quality assurance and breakpoint detection,
(4) deliver the metadata and data to various Swiss and global data centres and
(5) analyse decadal climate variability in Switzerland during the 19th century.
The data sets will be sent to several data centres, including the International Surface Pressure Database from which future global reanalysis data sets will be produced. Together with those data sets already digitised and some series in neighbouring countries, the new data series (if their quality permits) will be used to produce daily 2 km gridded weather reconstructions for Switzerland spanning the past ca. 200 years. Two approaches (an Ensemble Kalman Filter approach based on analogs and Reduced Space Optimal Interpolation) will be tested and applied.