Changing wind properties in south Sweden since the days of Tycho Brahe / Ändrade vindförhållande i södra Sverige sedan Tycho Brahes dagar

The famous Danish astronomer Tycho Brahe initiated meteorological observations on the Island of Ven that were recorded in a diary, starting in October 1582 and lasting almost uninterruptedly until April 1597. Although the observations were mainly qualitative due to the lack of proper instruments and procedures in those days, a lot of useful information can be extracted from the diary regarding cloud cover, precipitation characteristics, wind speed and direction, heat conditions, and the occurrence of thunder, halos, and northern lights. After the diary was found in the mid-19th century, La Cour (1876) transcribed the observations to quantitative measures, obtaining four values per day for a number of meteorological parameters. The transcribed observations from the diary may be used to investigate whether changes in the climate have occurred since the 16th century. In the present paper, the wind properties (direction and speed) from the diary, were compared to measurements from the 19th and 20th/21st century to determine if such changes have taken place. In accordance with results from previous studies, the data analysis showed shifts in the wind direction from the sector northeast – southeast to the sector south – west. These changes are more pronounced for the winter months compared to the summer months. No conclusions could be made regarding the wind speed, probably due to problems in transcribing the observations in the diary to quantifiable values. The observed changes in the wind direction are of significance for the wave and water level conditions around the south coast of Sweden, which in turn affect sediment transport and shoreline evolution.