The Meteorological Diaries of Johann Rudolf von Salis-Marschlins, 1781-1800

Weather and climate of the eighteenth and the first half of the nineteenth century, i.e. before the start of national weather services, is not very well understood. However, this was a climatically relevant phase, in particular the time around 1800 being part of the so-called Dalton Minimum. During the last years, the SNF-funded project «Swiss Early Instrumental Series (CHIMES)», located at the Institute of Geography and the Institute of History, aimed at digitizing and evaluating the Swiss early instrumental series, in the context of which also this master thesis has been written. The meteorological diaries of Johann Rudolf von Salis-Marschlins contain a rich collection of climatological data. Within the here studied years of 1781 – 1800, well over 10,000 pressure and temperature measurements, more than 4,000 observations of phenological phases, and close to 2,000 descriptions of precipitation events can be found. Despite their extraordinary wealth in data, however, the Marschlinian diaries played a minor role in historical climatology so far, which is mainly due to reported inaccuracies of the used instruments. With the construction and homogenisation of a monthly temperature and pressure series, this study was able to refute large parts of these reservations. However, the pressure data are only reliable from 1794 onwards. Additionally, the precipitation observations have been quantified to obtain monthly precipitation depth totals. Furthermore, monthly snow cover duration and some selected phenological phases have been studied and their potential evaluated. Although the accuracy of descriptions more than 900 different plants varies, they are very rich and have been remarkably underestimated so far (e.g. compared to Johann Jakob Sprüngli’s observations of the same time). In general, measurements and observations generally are of high quality and, once homogenised, of high value to historical climatology, although not all systematic errors could be resolved for all series. A continuation study of the entire Marschlinian record (1781 – 1823) is thus recommended. In addition to this analysis of the diaries’ contents, this thesis also contains a complete transcription of the first twenty years of diary entries, i. e. of 31 booklets with approximately 5,200 handwritten pages.

Online publiziert unter https://occrdata.unibe.ch/students/theses/msc/283.pdf