When digital climate data becomes handwriting again

The University of Graz climate data archive contains photographed monthly tables of meteorological observations from 1890 to 2004. According to the history of the meteorological station, observations from Graz have been documented since 1795.

It became especially exciting for me when I compared the sheets with the Graz University/Heinrichstrasse station in Climate Chronicle. I wanted to know whether digitally available values from more than 100 years ago really agree with the old handwritten records.

After looking through several climate sheets, I found exactly the values that also appear in the Climate Chronicle station data. This was not a new calculation or a spectacular data trick, but a direct connection to the original observation. A number in a dataset became a handwritten entry on old paper.

There is something genuinely impressive about seeing papers this old. They physically exist, and some of the values recorded on them can now be seen here on my website.

The maximum temperature is particularly easy to compare in the images: the value on the climate sheet matches the Climate Chronicle station view exactly. The precipitation values also agree almost completely. Precipitation amounts in the digital data from GeoSphere Austria are rounded to whole millimetres.

The University of Graz meteorological station has been located at the present campus since 1891, although it was moved slightly within the campus due to various construction projects.

Staff at the Institute of Physics catalogued the sheets and recorded usable metadata. This includes information about instruments, calibrations and repairs, the names of the observers, and documented changes of location. Graz University Library had the sheets photographed.

The archive website is organised by decade. It allows visitors to move from 1890 to the last classic monthly tables in November 2004. After that, station records and data entry were largely continued electronically. The published images are available under the Creative Commons Attribution 4.0 International licence.

The Atmospheric and Climate Physics group does not merely preserve old tables. It continues to operate the university meteorological station. Its long continuous series is recognised as a WMO Centennial Observing Station. Through this programme, the World Meteorological Organization highlights stations whose long, high-quality series are especially valuable for assessing climate variability and climate change.

Together with GeoSphere Austria, the research group operates two semi-automated weather stations. Their measurements feed into the GeoSphere Austria meteorological observing network, which meets international WMO quality standards and provides a basis for weather forecasts, climate products and climate research.

Its research priorities include high-quality climate station data, historical climate variability, and regional changes in climate and hydrology. Regional analyses examine, among other topics, heavy precipitation and droughts in the warming Alpine region. Another focus is satellite-based atmospheric observation with GNSS radio occultation, which uses navigation satellite signals for stable global climate observations.

Long observation series are particularly important for historical climate research. They help to better understand natural variations and place rare extreme events in context. The WMO also describes the rescue of historical weather data as essential for future research into climate variability and climate change. The old Graz sheets are therefore archive material, traceable measurement documentation and material for current research - and they help me prepare data for Climate Chronicle in the first place.