Högfrekventa tryckvariationer under de senaste århundradena

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Long time-series of pressure measurements often have high quality because the early instruments are more or less the same as the modern ones. A time-series from Lund consisting of three daily measurements from 1780-1997 has been homogenised and is therefore suitable for analysing possible influences of the enhanced greenhouse effect. According to a two-layer model of the atmosphere one finds a shift in the frequency of baroclinic instability due to an increased temperature gradient caused by the increasing CO2. Baroclinic instability over the Atlantic Ocean is the main cause for frontal zone production, causing cyclonic activity over the southern part of Scandinavia. Changes to the baroclinic instability would therefore be traceable in the time series from Lund. The period 1859-1997 was analysed by spectral analysis. The measurements are unevenly sampled so prior to applying various techniques of spectral analysis it was necessary to interpolate the tim...