Background information on the Rothamsted Weather Station

Background

Rothamsted has one of the longest continuous sets of meteorological recordings in the world. Total rainfall and wind direction have been measured since 1853, temperature since 1878, sunshine from 1890, wind force from 1917, radiation from 1931, wind run since 1946 and wind speed since 1960. Annual rainfall averages 704mm (1971-2000), but ranges widely from 380mm in 1921 to 973mm in 2000. Mean annual temperature 1878-1990 at Rothamsted was 9ºC; average annual temperature is now more than 1ºC higher than the 1878-1990 average (for more details refer to Guide to Classical Experiments 2006, p 44-45). Since January 1st 2004, meteorological records have been measured by a range of sensors attached to an automatic data logger; some manual observations continued to be made until May 2007.

Rothamsted took over the management of the farm at Woburn in the 1920's and the first meteorological records date back to 1928. Annual rainfall averages 649mm (1971-2000). Temperature, rainfall, sunshine, wind force and wind direction have been measured since 1928. Wind speed and wind run have been measured since 1968 and radiation measurements started in 1981. Manual observations ceased on 1st July 1999, and meteorological records are now measured by a range of sensors attached to an automatic data logger. The mean annual temperature (1971-2000) was 9.6 ºC.

Meteorological data was first collected in Brooms Barn in 1963. Fewer variables are measured than at Rothamsted and Woburn. Rainfall averages 612mm (1963-2008). Mean annual temperature 1964-2008 was 9.9°C. Dew point, wind run, sunshine hours, vapour pressure and relative humidity have also been measured and/or calculated. Data from 1982 is available in e-RA.

The Brooms Barn meteorological station is approx. 30m from the main buildings, which are approx. 10m high. This may cause some interference with the measurement of wind speed and wind direction, as ideally a mast with wind sensors should be a minimum of 10 times the height of the nearest building away from the nearest building (ie at least 100m apart). This gives enough fetch for the wind to settle down. The met station and main building have always been in these positions.