Daily air temperature and pressure series for Uppsala (1722-1998)

Abstract

Daily meteorological observations have been made in Uppsala, Sweden, since 1722, and complete series of air temperature and sea level air pressure have been reconstructed and homogenised for the period 1722-1998. The reconstruction work was based on the hand written registers and printed monthly bulletins before 1985, after which data was directly stored on computers. Methods to determine daily average temperatures from the typically available 2-3 observations per day were developed. These methods take into account observation times and cloud amount. Pressure reductions back to 1840 involved only routine calculations, while earlier pressure data needed major homogenisations. All data were searched for errors by comparisons with previously determined monthly averages and by different plotting techniques, mainly comparing with independently reconstructed data from Stockholm, 65 km south of Uppsala. This comparison also shows that the quality of the data is generally good, although the reliability is lower before the mid-19th century. Results are given illustrating changes in the daily average temperature and pressure climate on a 200-250 year time scale.