Hohenpeißenberg Meteorological Observatory

A network node on a hill

In 1780 the Elector Karl Theodor founded the Societas Meteorologica Palatina in Mannheim, which supplied standard instruments to observers at some 30 stations across Europe and North America, who recorded at fixed hours and sent their readings to Mannheim for publication. Hohenpeißenberg, a hill of about 990 metres in the Bavarian foothills of the Alps, joined it, and observations began on 1 January 1781, carried out by Augustinian canons from the monastery of Rottenbuch.

The Palatina society dissolved in 1793, after the political upheavals of the French revolutionary wars, but the canons kept observing on their own. The record that began in 1781 never stopped.

From monastery to weather service

In 1878 the station joined the network of the new central meteorological institute in Munich, and in 1934 the Reich weather service took it over. The Deutscher Wetterdienst (DWD), Germany's national meteorological service, runs it today, and in 1981 published 200 years of observations covering 1781 to 1980.

Because the site is on a hill outside a city, its record is little affected by the urban heat island, which makes it a reference for how the climate of central Europe has changed. It is a station of the Global Atmosphere Watch programme of the World Meteorological Organization, with ozone soundings and trace-gas measurements added in the twentieth century.

What the record shows

Two and a half centuries of daily temperature, pressure and precipitation show clear warming in the last decades, and the long series provides a check on reconstructions made from tree rings and documents. The earliest part of the record, which relied on instruments of the 1780s, has been carefully compared with later instruments to correct for changes in thermometers and exposure.

Reading a record of two centuries

A series that begins in 1781 crosses many changes: the thermometers, the screens, the observers, the time of the readings, even the units. Hohenpeißenberg's record is useful because those changes have been studied, and the DWD publishes the adjustments. A mountain site also has a micro-climate: temperature inversions in winter mean that the hill is sometimes warmer than the valley. The record has shown that the greatest warming in central Europe took place after about 1980, and its ozone record, begun in 1967, is among the longest in the world. The key is a stable organisation that keeps the instruments and the metadata, which here is the weather service.

Instruments and technologies

• Standard Palatina instruments A Mannheim-made set of a thermometer, barometer, hygrometer and magnetic needle, calibrated alike and issued to every station; observations at 07:00, 14:00 and 21:00 local time.
• Modern automatic station Sensors for temperature, humidity, wind, pressure and radiation with parallel manual observation for continuity.
• Ozone sounding Balloon-borne ozone sondes released regularly give a profile of ozone through the stratosphere.

Timeline

• 1781 Observations begin on 1 January within the Palatina network.
• 1793 The Palatina society dissolves; the canons continue observing on their own.
• 1878 Joins the network of the new meteorological central institute in Munich.
• 1934 Taken over by the Reich weather service.
• 1981 Deutscher Wetterdienst publishes 200 years of observations (1781–1980).

Key lessons for observation today

• Standard hours outlive the instruments The three daily observation times set in 1781 shaped climatological practice for two centuries. Early protocol choices are the hardest to change and the most valuable to get right.
• The record continued when the network ended The Palatina society dissolved and the station carried on. A node that is run by a stable local institution outlives the network around it.
• Site choice is a climate decision A site outside a city gives a series that city growth does not distort. Siting rules belong in the design of any climate station.

Sources

• Wikipedia, Hohenpeißenberg Meteorological Observatory
• Schneefernerhaus, Deutscher Wetterdienst (GAW Global Station Zugspitze/Hohenpeißenberg)
• Meteorologisches Observatorium Hohenpeißenberg (German encyclopedia entry)