Air pressure

Barometer observations have been daily since 1754 but are more demanding to analyze than the temperature observations. The oldest barometer measured the height of the mercury column in Swedish inches (=29.69 mm). No thermometer was attached and the temperature near the barometer was not observed before 1785. The lack of temperature observations, an unknown exact height of the barometer position and other unkown properties of old barometers used make it difficult to convert the oldest barometer recordings to the modern unit of hPa reduced to 0°C, normal gravity and sea level. Despite these difficulties, efforts have been made to convert all individual observations to hPa back to 1756. Homogenization of the record has been done by adjustments such that the long term trend agrees with other long air pressure measurements in Northern Europe. The homogenized record is judged to not reliably show long-term trends in air pressure, but the short term day-to day changes are likely rather accurate.

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Publications

A detailed discussion of how the air pressure observations have been made and how the homogenized series was developed is provided in the following publication.

  • Moberg A, Bergström H, Ruiz Krigsman J, Svanered O. 2002: Daily air temperature and pressure series for Stockholm (1756-1998). Climatic Change 53: 171-212

Detail on a barometer constructed by Daniel Ekström around 1750. This barometer was probably used for the daily meteorological observations at the old astronomical observatory in Stockholm most of the time from 1754-1858. (Photo: A. Moberg).