In the context of climate change, there is an
increasing demand for homogeneous long-term observation time series to better
understand the role of trends compared to natural climate variability.
Particularly data on a daily or even hourly basis from periods prior the
installation of meteorological networks by regional or national weather
agencies (e.g., 1868/69 in Baden) are very helpful to better address questions
related to extremes or the temporal variability of climate parameters.
Such a time series is presented by the Karlsruhe
climate series, which is provided online by the German Weather Service (DWD) including
3 observations per day for the period from 1876 to 30 Oct. 2008 (after 2008 the
station was relocated to Rheinstetten, approx. 10 km southwest of Karlsruhe).
In fact, the whole climate series dates back to the 18th century with the
operational meteorological observations by Johann Lorenz Böckmann, which was a
Professor at the gymnasium in Karlsruhe. Copies of the handwritten records are
almost completely available at the manuscript departments of the University Libraries
in Karlsruhe and Heidelberg, at the State Archive Mannheim, at the paper
archive of DWD in Offenbach, partially with parallel observation records, and
as extracts at the archive of the Karlsruhe newspaper.
Within the project Karlsruhe Climate Series, the
records were digitalized until 1876 and partly complemented and corrected with
parallel observation series at the stations of Karlsruhe-Hochschule and
Karlsruhe-airport 1937-1944/45. Thus, one of the longest climate series from
1778 to 2008 is now available for several parameters such as temperature,
precipitation, pressure, wind, and other meteorological information.
Preliminary analyses of the climate series provide some interesting results and
suggest new insights in the climate of the region of Karlsruhe.
Currently, the climate series are processed and
statistically analyzed. For example, maxima and minima were reconstructed from
the 3 daily observations using a 13-year sub-series on an hourly basis (see
Fig. 1). From that, temporal variability and changes in the number of frost and
hot days (Tmax ≤ 0°C; Tmax ≥
30°C) can be investigated (Fig. 2). This helps to better interpret and assess the
decrease and decrease, respectively, observed since the mid 20the century. It
is also possible to study the whole variability of the weather prior to climate
change, for example, concerning the magnitudes and duration of heat and cold
waves. The climate series with its various meteorological parameters also
enables the study of other phenomena, for example extreme precipitatiation
events (Fig. 3) or the conditions around the “year without summer”, 1816.
Fig. 1: Absolute records of minimum and maximum temperatures
within the decades indicated between 1778 and 1875 (extract).
Fig. 2: Number of hot days (Tmax
≥ 30,0 °C) in Karlsruhe with moving average (11-yrs) and
linear trend between 1800 and 2011.
Fig. 3: Annual precipitation sums in Karlsruhe between
1801 and 1822.