The long-term daily Central Belgium Temperature (CBT) series (1767-1998) and early instrumental meteorological observations in Belgium

This article presents the problems and results of constructing the Central Belgium Temperature series, a homogeneous multi-site instrumental daily maximum and minimum temperature series which has been made for the time period 1767 to the present. First, an outline of the history of early meteorological observations in Belgium is presented. The long-term daily observations which were subsequently used in the construction of the Central Belgium Temperature series received special attention. The series consists for a larger part of high quality and well documented daily temperature readings by Adolphe Quetelet, started in 1833 at the Royal Observatory of Brussels, Belgium and continued in 1913 under the auspices of the autonomous Royal Meteorological Institute of Belgium. For the period before 1833, several long-term climatological series carried out by natural scientists, physicians, etc., have been retroactively incorporated into the existing series using linear regression techniques based upon observations at the two sites for overlapping periods. Several series have been discovered during the search for meteorological manuscripts and publications by the two Belgian IMPROVE teams.