The temperature in Bremen since 1803 - embedding data fragments into homogeneous time series
Over several decades the physician and astronomer Wilhelm Olbers (*1758, †1840) has written many manuscripts to meteorological topics. Few of his works were published, most fell into oblivion, so also Olbers' measurements of temperature and pressure from the years 1803-1822, although these meteorological observations are the first continuous and reliable measurements of this kind in Bremen. This article deals with the monthly and annually averaged temperatures from 1803 to 1822, which are taken from the literary legacy of Olbers and are partially reconstructed from his manuscripts. The linkage of this series of measurements to the well-known Bremen temperature series is discussed, which begins in 1829 and is today continued by the German Weather Service (DWD). The method we propose for the adjustment of the combined data (with a gap of 6 years 1823 to 1828) is based on the extremely high correlation which the annually averaged data of the Bremen time series has with corresponding data from other monitoring sites. Data from De Bilt, Berlin, Prague, Hohenpeissenberg and Stockholm are used. The result is a temperature time series for Bremen from 1803 to today, which may be regarded as homogeneous at least to some extent.