http://bolin.su.se/data/stockholm-historical-daily-slp-1 Anders Moberg Bolin Centre Database 2019 Datafile Atmosphere Weather observations Air pressure Barometer Daily data Early instrumental data Homogenized data Sweden Stockholm Earth science > Atmosphere > Atmospheric pressure > Sea level pressure Anders Moberg 2019-08-02T16:54:18+00:00 English 1 None The data are included in two files having 6 columns, available in two file formats:<p> 1. plain text files (.txt)<p> 2. tab-separated value files (.tsv)</p> <p> File content:</p> <p> Column 1: Year<p> Column 2: Month<p> Column 3: Date<p> Column 4: Morning SLP value<p> Column 5: Noon SLP value<p> Column 6: Evening SLP value</p> <p> SLP unit: hPa. Code for missing value: NaN.</p> <p> More detailed information about the data file content is found in a README text file. The observation site is included in the national station network managed by the Swedish Meteorological and Hydrological Institute (SMHI), with station number 98210 (manual station) and 98230 (automatic station), but data in the current dataset can differ from those in the SMHI database. Barometer observations have been made daily since 1756. 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 records from Northern Europe. Details of how this was achieved are provided in Moberg et al. (2002). The sub-daily SLP series from Moberg et al. (2002) covers the period 1756⁠ – 1998. Updating to the end of 2012 has been made here by merging with data obtained from the SMHI. No more recent values are included. However, sub-daily SLP values for 2013⁠ – 2018 are available in the associated dataset with <a href="https://bolin.su.se/data/stockholm-historical-barometer"> barometer observations in original units</a>. Those data are in turn obtained from the <a href="http://opendata-download-metobs.smhi.se/explore/#">SMHI resource Öppna Data</a>. If required, those data files can be used to extend the long sub-daily SLP records in time to the most present. The number of observations each day has changed through time, as follows: 1756-01-01⁠ – 1784-05-31: 2 observations (morning and evening) 1785-06-01⁠ – 2012-12-31: 3 observations (morning, noon, evening) Information about instruments and original data sources is available in the comments to the associated dataset with <a href="https://bolin.su.se/data/stockholm-historical-barometer">barometer observations in original units</a>.