An Evaluation of Meteorological Observations by Samuel Studer (1807-1818)
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An Evaluation of Meteorological Observations by Samuel Studer (1807-1818) Master’s Thesis Faculty of Science Oeschger Centre for Climate Change Research University of Bern By: Chantal Hari 2021 Supervisor: Prof. Dr. Christian Rohr Institute of History, Oeschger Centre for Climate Change Research, University of Bern Co-Supervisor: Prof. Dr. Stefan Brönnimann Institute of Geography, Oeschger Centre for Climate Change Research, University of Bern 1 2 Abstract Early instrumental measurement series contain a vast amount of climatological data. Within this study, the meteorological observations by Samuel Studer from 1807 to 1818 are evaluated. By summarizing information on the life of Studer and his social environment, this study works out the motivation behind the lengthy endeavor of noting sub-daily measurements and observations for 48 years. The aim of this study was to report on the limitations and potential of the series and to make the series more accessible for future research. The temperature and air pressure measurements from Studer underwent a homogeneity assessment. In addition, the precipitation observations were transformed into quantitative data. A case study further investigated the climatic consequences of the Unknown Eruption and the eruption of Mount Tambora. The research question, whether the climatic consequences of these eruptions can be found in the Studer series, is answered by applying hypothesis testing to the monthly data. This study has presented the Studer series and has made it more accessible to future research. The main limitations concern the availability of the metadata for the entire Studer series and the vast amount of missing values during Studer’s travels (especially in the summer months). The length and high resolution of this series, however, provide a great opportunity for it to be embedded in studies that also include other early instrumental measurements series of Switzerland; thus, it is a valuable source of information for climate research. 3 Acknowledgments This thesis has evolved over more than two years. Without the support and help of many people, this endeavor would not have been possible. Therefore, I would like to express my gratitude to those who have played a major part in the development of this thesis, even though not everyone can be named. I would like to thank first and foremost my supervisor, Prof. Dr. Christian Rohr. He has guided me through all my studies and has given me guidance through this path, from my seminar thesis, my bachelor’s thesis, and finally this master’s thesis. He has even played a major role in helping me find my academic way. By introducing me to the Master’s in Climate Sciences, he has helped to shape my academic path and has encouraged me to pursue it. I would like to thank him for his support, and especially for never doubting me. I am also very thankful to my co- supervisor, Prof. Dr. Stefan Brönnimann, who has given me advice on many of my various questions concerning the evaluation of the early instrumental measurement series. I am grateful to have benefitted from his broad range of knowledge and expertise. I would also like to thank Yuri Brugnara for his help and perseverance with my many questions. Additionally, my thanks go to the Oeschger Centre for Climate Change Research for the financial support for this thesis. In addition to the academic support, my personal environment has also been decisive for the successful implementation of this thesis. I would like to thank Luc Hächler, Melina Hodel, and Andrea Schaub for taking the time to proofread and critically question my thesis. My thanks go also to PD Dr. Christoph Frei. Thanks to his R packages, many analyses have been made easier and faster to compute. In his lecture “Analysis of Climate and Weather Data,” taught at ETH Zurich, he delivered information that has been essential for this thesis. 4 Table of Contents 1. Introduction .......................................................................................................................... 8 1.1. Research Questions/Aim and Limitations of the Thesis ................................................. 9 1.2. State of Source Materials ............................................................................................... 10 1.3. State of Research ........................................................................................................... 11 1.3.1. Historical Climatology ........................................................................................... 11 1.3.2. Early Instrumental Measurement Series and Volcanic Eruptions .......................... 13 1.4. Structure of the Thesis ................................................................................................... 14 2. Methods ............................................................................................................................... 16 3. Source Review ..................................................................................................................... 21 3.1. Samuel Studer ................................................................................................................ 22 3.2. Source Criticism ............................................................................................................ 28 3.2.1. Classification of the Source .................................................................................... 28 3.2.2. Condition and Location of the Source .................................................................... 29 3.2.3. Language, Linguistic Peculiarities, and Dating ...................................................... 30 3.2.4. Gaps and Changes of Location ............................................................................... 31 3.3. Content of the Source .................................................................................................... 32 3.3.1. Three Daily Measurements ..................................................................................... 32 3.3.2. Phenological Observations, Earthquakes, and Others ............................................ 35 4. Temperature, Air Pressure and Precipitation Records .................................................. 38 4.1. Metadata on Measurement Instruments and Schedule .................................................. 38 4.1.1. Thermometer .......................................................................................................... 39 4.1.2. Barometer ............................................................................................................... 44 4.1.3. Measurement Schedule ........................................................................................... 45 4.2. The Temperature Measurements ................................................................................... 50 4.2.1. Data Processing, First Impressions, and Quality Control ....................................... 50 4.2.2. Breakpoint Detection and Homogeneity Adjustment ............................................. 59 4.2.3. Trend Analysis ........................................................................................................ 66 4.2.4. The Corrected Temperature Series ......................................................................... 68 4.3. The Air Pressure Measurements .................................................................................... 70 4.3.1. Data Processing ...................................................................................................... 70 5 4.3.2. First Impressions and Quality Control .................................................................... 76 4.3.3. Breakpoint Detection, Homogeneity Adjustment, and Trend Analysis ................. 78 4.3.4. The Corrected Pressure Series ................................................................................ 86 4.4. The Precipitation Observations ..................................................................................... 87 5. Case Study: Impacts of the Unknown Eruption and the Mount Tambora Eruption .. 93 5.1. Climatic and Historical Background ............................................................................. 93 5.1.1. The Effects of Solar and Volcanic Forcing ............................................................ 93 5.1.2. The Unknown Eruption .......................................................................................... 95 5.1.3. The Mount Tambora Eruption ................................................................................ 97 5.2. Results ........................................................................................................................... 99 5.2.1. Temperature ............................................................................................................ 99 5.2.2. Air Pressure .......................................................................................................... 101 5.2.3. Precipitation .......................................................................................................... 104 5.3. Case Study Conclusion ................................................................................................ 105 6. Conclusion and Outlook ................................................................................................... 107 7. Registers ............................................................................................................................ 111 7.1. List of Abbreviations ..................................................................................................