Analysis of wind direction measurements made by the Rospini family in Graz (Austria), 1822-1850 CE

The Austrian National Library has digitized several volumes of the newspaper "Grätzer Zeitung", which contains daily measurements (morning, noon and evening) of temperature, pressure, short simple weather descriptions, wind direction, and wind strength, recorded in the historic center of Graz by Mr. Rospini (and later by his son and grandsons). Other volumes of the newspaper are available on microfilm or have been found in archives. The measurement series of the Rospini family started as early as 1781, and have been continuously published in the "Grätzer Zeitung" from 1795 onwards. However, in the first years only temperature and pressure data were published and the first publications of wind directions began in March 1822. Thus, we analyze an almost uninterrupted record of wind directions from 1822 to 1850. The measurement times for this period are given as 7 a.m., 3 p.m. and 10 p.m. To assert the validity of the data, we compare it with modern data as well as with the other measurements of the Rospinis. Initial analysis reveal an improvement in measurement accuracy during the measurement period. I.e. the year-round seasonal distributions of the main wind directions differ significantly in the 1820s with respect to modern data, whereas those of the 1840s are comparable.