The Swiss National Basic Climate Network (Swiss NBCN)

The Swiss National Basic Climatological Network combines the most important climatological stations within the observation network of MeteoSwiss (Begert et al. 2007). Currently it consists of 29 climate stations recording different parameters and 46 precipitation stations. Time series of temperature, precipitation and sunshine duration of the Swiss NBCN stations date partially back to the middle of the 19th century and are completely digitized and homogenized.

The surface observation stations of the Swiss NBCN were selected, among other criteria according to the following criteria:

• Long-term data series of different climatological parameters
• Representative geographical distribution
• Embedding into international observation networks

Currently the following types of stations are members of the Swiss NBCN (fig. 2):

• Climate stations: 29 stations at which the five parameters temperature (mean, minimum, maximum), precipitation and sunshine duration are available (fig. 3). Long-term data series of all variables exist predominantly below 1000 m above sea level. The higher altitude stations provide in most cases only long-term time series of mean temperature and precipitation.
• Precipitation stations: 46 stations measuring precipitation only and completing the climate stations of the Swiss NBCN in response to its greater spatial variability. The selection of the additional precipitation stations was defined on objective basis using a cluster analysis (Begert, 2008).

Embedded in the Swiss NBCN are observation stations of the following international climatological networks:

• GSN: The GCOS Surface Network conduces for the global climate observation and consists of 980 stations worldwide. It was defined by the Global Climate Observing System (GCOS) programme of the WMO in 1997.
• RBCN: The Regional Basic Climatological Network comprises about 2600 surface monitoring stations in six WMO regions and conduces for the continental climate observation. 8 stations of the Swiss NBCN are members of the RBCN. By definition all GSN-stations are also RBCN-stations.

The 8 stations of the GSN/RBCN are not sufficient for regional climatological questions, in particular for the alpine region. The Swiss NBCN can be considered as a national expansion of the GSN/RBCN (fig. 1).

• Begert, M., Seiz, G., Foppa, N., Schlegel, T., Appenzeller, C., Müller, G. 2007: Die Überführung der klimatologischen Referenzstationen der Schweiz in das Swiss National Climatological Network (Swiss NBCN). Arbeitsberichte der MeteoSchweiz, 215, 43 pp.
• Begert, M. 2008: Repräsentivität der Stationen im Swiss National Basic Climatological Network. Arbeitsberichte der MeteoSchweiz, 217, 40 pp.
• Füllemann C*, Begert M*, Croci-Maspoli M*, Brönnimann S (UniBe), 2011: Digitalisieren und Homogenisieren von historischen Klimadaten des Swiss NBCN - Resultate aus DigiHom
   Arbeitsberichte der MeteoSchweiz, 236, 48 pp.