Homogenized monthly mean temperature
De Bilt, the Netherlands
version 1, December 2006
Theo Brandsma
Technical description
Corrections have been made for:
  • relocation combined with a transition of large open hut to a wooden Stevenson screen (September 1950).
  • relocation of the Stevenson screen (August 1951).
  • lowering of Stevenson screen from 2.2 m to 1.5 m (June 1961).
  • transition of artificial ventilated Stevenson screen to the current KNMI round-plated screen (June 1993).
  • warming trend of 0.11°C per century caused by urban warming.
Please note the following:
  • the transition of the wooden Stevenson to a PVC Stevenson screen (August 1980) did not have a noticeable effect on the daily mean temperatures; consequently no corrections had to be applied.
  • from 1951 onwards, KNMI shifted from so-called climatological temperature measurements to synoptical measurements. However, the climatological measurements continued to 1970. For the 1951-1970 period these measurements may be considered as more reliable than the synoptical measurements. Therefore, in the homogenized series the climatological measurements extend to 1970.
  • the present version of the series may change as soon as new results come available from the efforts of KNMI to homogenize the temperature series of De Bilt on a daily base, taking into account weather-dependent corrections.
Relevant publications
  • Brandsma, T. en J.P. van der Meulen, Thermometer Screen Intercomparison in De Bilt (the Netherlands), Part II: Description and modeling of mean temperature differences and extremes, Int. J. Climatology, 2006 (submitted), abstract and full text
  • Meulen, J.P. van der en T. Brandsma, Thermometer Screen Intercomparison in De Bilt (the Netherlands), Part I: Understanding temperature differences for particular days, Int. J. Climatology, 2006 (submitted), abstract and full text.
  • Brandsma, T. en G.P. Können, Application of nearest-neighbor resampling techniques for homogenizing temperature records on a daily to sub-daily level, Int. J. Climatology, 2006, 26, 1, 75-89
  • Brandsma, T., G.P. Können en H.R.A. Wessels, Empirical estimation of the effect of urban heat advection on the temperature series of De Bilt (The Netherlands), Int. J. Climatology, 2003, 23, 829-845, abstract.