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2 Atmospheric Essential Climate Variables 
2.1 General information 
Meteorological observations have a long tradition in Europe. State-owned weather services 
in Germany started collecting climate data at the end of the 19th century, but only after the 
reunification of Germany in 1990 the data have been recorded and processed according to 
unified standards. With the use of automated stations, the frequency of measurements con 
siderably increased with the result that today these stations record and store the data in in 
tervals of one to 10 minutes. In addition, about 300 automated secondary weather stations 
with voluntary observations also measure and store climate relevant data in intervals of 1 to 
10 minutes. About 500 automated precipitation stations have the same measured intervals. 
Further more, there is still a large number (>1000) of conventional precipitation stations, 
which record meteorological parameters once a day by voluntary observers. 
Relevant climatological requirements - for example, relative to the networks operated by the 
German Meteorological Service (DWD) - have always been given careful attention, since 
both real-time and climate applications benefit from the precision required for climatological 
purposes. For this reason, DWD recognizes and respects the GCOS Climate Monitoring 
Principles (GCMP see decision UNFCCC 11/CP.13) for its primary weather stations and with 
some restrictions also for its secondary weather stations. 
Twelve National Reference Stations (Aachen, Brocken, Fichtelberg, Frankfurt/Main, Görlitz, 
Helgoland, Hamburg-Fuhlsbüttel, Hohenpeissenberg, Konstanz, Lindenberg, Potsdam and 
Schleswig) are being established in the national network. At these sites, conventional and 
new automatic measuring devices are operated in parallel. All measured data have been and 
are subjected to thorough quality checks and are stored in digital form. 
2.2 Contributions to the GCOS Networks from international rele 
vant stations 
2.2.1 Contributions to the GCOS Surface Network (GSN) 
In Germany five stations have been selected for the GCOS Surface Network i.e. four DWD 
stations and one station (Neumayer) is operated by the Alfred Wegener Institute (AWI) in the 
Antarctic. 
• Hamburg-Fuhlsbüttel (WMO-Nr. 10147) 
• Lindenberg (WMO-Nr. 10393) 
• Frankfurt/Main (WMO-Nr. 10637) 
• Hohenpeissenberg (WMO-Nr. 10962) 
• Neumayer (WMO-Nr. 89002) 
The four DWD stations all belong to the network of National Reference Stations. 
Hamburg-Fuhlsbüttel: 
The Hamburg-Fuhlsbüttel station is an aeronautical meteorological office that was estab 
lished in 1891 as an observatory. In 1955, it was moved about 270 m to the west, and it is 
now located on the grounds of Hamburg Airport. In 1995, the station was moved again - this 
time, about 700 m to the south-west. In that same year, a transition was made to semiauto 
matic operation, and since then the station has automatically recorded air temperature (at 
heights of 2 m and 5 cm), ground temperature, humidity, air pressure, wind direction and 
wind speed, as well as precipitation and sunshine duration. This year the instrumentation and