Thermometer screen intercomparison in De Bilt (the Netherlands)—Part II: description and modeling of mean temperature differences and extremes

Abstract

ABSTRACT:Temperatures of nine thermometer screens during a 6-year field experiment in De Bilt (the Netherlands) have been compared. The screens are currently in use throughout the world and comprise the following types: an aspirated Young screen, four naturally ventilated round-shaped multi-plate screens (KNMI, Vaisala, Young, Socrima), a slightly aspirated version of the KNMI screen, a synthetic Stevenson screen (both aspirated and naturally ventilated) and a naturally ventilated wooden Stevenson screen. The multi-plate KNMI screen served as a reference. For the daily minimum, maximum, and mean air temperatures (T n , T x , T mean ), the absolute seasonal mean differences with the reference were almost all ≤ 0.1°C. An exception is the aspirated Young screen for which differences in mean T x in summer (JJA) are most notable and amount to −0.43°C. The differences of the individual T n , T x , T mean values may be much larger than their seasonal averages. For the aspirated Young and the naturally ventilated Stevenson screens they are most notable, where the Young is generally cooler (T x and T mean ) and the Stevensons warmer than the reference. The absolute temperature differences between the screens and the reference are shown to increase with decreasing cloud cover and windspeed. Furthermore, using the original 15-s samples it is shown that random variations cause fast-responding screens to have more extreme T n , T x values than slow-responding screens. For a supposed transition of the natural ventilated synthetic Stevenson screen to the reference screen, transfer functions are successfully developed for the 10-min temperature data and the daily T n and T x data. It is argued that the explained variance of the models could have further improved when high-accuracy (especially in the range 0-3 m/s) windspeed measurements were available (at screen level and position).

The construction of a Central Netherlands temperature

“…From around 1990 onwards, a new automated observing system was gradually introduced using small multi-plate thermometer screens. This transition has had a negligible effect on monthly mean temperatures (Brandsma and van der Meulen, 2008).…”

Impact of two different sized Stevenson screens on air temperature measurements

“…E-mail: sbuisans@aemet.es which have appeared in the scientific literature since the 19th century (e.g. Wild, 1879;Marriott, 1879;Gill, 1882;Whipple, 1883;Mawley, 1897;Hazen, 1885;Margary, 1924;Drummond, 1943;Chandler, 1964;Sparks, 1972;Laing, 1977;Andersson and Mattisson, 1991;Richards et al, 1992;Parker, 1994;Nicholls et al, 1996;Nordli et al, 1997;Böhm et al, 2001; Van der Meulen, 2003;Brunetti et al, 2006;Perry et al, 2007; Van der Brandsma and Van der Meulen, 2008;Azorín-Molina and Azorín-Molina, 2008;Martínez-Ibarra et al, 2010;Clark et al, 2014;Burton, 2014). In Spain, a pioneering project on intercomparison of thermometer screens corresponded to the Spanish-funded SCREEN project coordinated by the Centre of Climate Change (C3; http://www.c3.urv.cat/; last accessed 1 November 2014) which assessed the screen bias incorporated into the longest Spanish air temperature records by time-changing thermometric exposures; paired air temperature observations were taken using the old Montsouris stand and modern Stevenson screens (for details see Brunet et al, 2006).…”

Thermometer screen intercomparison in De Bilt (The Netherlands), Part I: Understanding the weather-dependent temperature differences)

“…sonic anemometers) especially in the range 0-3 m/s. Together with Part II (Brandsma and Van der Meulen, 2007), this paper should give an adequate basis for assessing the impacts of screen changes in countries with climates comparable to those of the Netherlands.…”

“…This type of analysis should always precede a statistical analysis of the data. In Part II (Brandsma and Van der Meulen, 2007) we concentrate on the description and modelling of the mean temperature differences and extremes. The interest of the climatologist is to prevent artificial breaks due to screen changes or to have the ability to correct these breaks.…”