The climate station of the University of Hohenheim: analyses of air temperature and precipitation time series since 1878

At the University of Hohenheim (UHOH), one of the longest records in Germany concerning meteorological surface data exists. Since the late nineteenth century, time series of several surface variables such as temperature, precipitation, wind and relative humidity have been measured. Particularly, since 1878, almost continuous time series of temperature and precipitation are available. We are focusing our analysis on temperature as well as on precipitation. We demonstrate that the UHOH data provide another homogeneous, and from other sources, independent time record. Its errors are also well specified. Long time series are essential for investigating climate trends as well as statistics of extreme events. We are investigating trends in temperature and compare these to climatologies. We observe an increase in temperature of about 0.6 °C between 1971 and 2000 in comparison to the average between 1878 and 2002. Not only this amount but also the shape of the temperature curve are in striking agreement with trends assessed by the Intergovernmental Panel on Climate Change in the Northern Hemisphere. It shows also the same behavior of the Climate Research Unit (CRU) climatology using the grid point surrounding our measurement site. This demonstrates a low influence of local effects on the temperature trend at our measurement site. It also indicates that temperature fields have a large spatial correlation length. We found a reduction of 2.2 frost days and a reduction of 1.2 ice days per decade. In the summer of 2003, the mean temperature was 21.8 °C, which was 5 standard deviations larger than the mean value of 16.9 °C between 1878 and 2002. The precipitation patterns at our site show a significant increase of precipitation in winter, whereas in summer a trend is not significant. Particularly in winter, we find an increase of 12%. We also detected indications of a shift of precipitation to more extreme values. Copyright © 2006 Royal Meteorological Society.