The Lund instrumental record of meteorological observations: reconstruction of monthly sea‐level pressure 1780–1997

The reconstructed surface air pressure series from Lund, southern Sweden, covers the period 1780–1997 and comprises more than 234 000 valid observations (three observations per day), i.e. >98% of all possible observation occasions. For the Early Instrumental Period (EIP; 1780–1860) data were digitised from the original records. For most of the Modern Instrumental Period (MIP; 1861–) a series was compiled from various databases containing instrument corrected data. During EIP, the series of raw monthly means show several substantial inhomogeneities. With the aid of a detailed reconstruction of the station history, it was possible to remove almost all inhomogeneities during EIP by applying the correct instrument corrections (for barometer temperature, to standard gravity and to mean sea‐level pressure) to the series of original observations. In particular, corrections for the temperature and altitude of the barometer eliminated several inhomogeneities. A prerequisite for applying these corrections is the availability of high‐resolution data (actual raw observations or daily averages). Further homogenisation was attained by intercomparison of the monthly mean pressure with acknowledged homogeneous series (mainly the UKMO monthly grid, station records from Copenhagen and Edinburgh). Statistical tests of homogeneity showed that no substantial inhomogeneities remain in the final version. The modern part of the final monthly pressure series largely follows that of the southern Baltic Sea region. Furthermore, it shows relatively high pressure during spring (MAM) in the period 1780–1820, which was paralleled by severe wind erosion in southern Scandinavia during this time. Relatively high pressure throughout the year is also notable during a period of precipitation deficit in 1970s. Copyright © 1999 Royal Meteorological Society