Principal Investigators: Rüdiger Glaser (University of Freiburg), Manfred Küppers (University of Hohenheim), Michael Friedrich (University of Hohenheim), Alexander Land (University of Hohenheim), Eberhard Kienzle (University of Esslingen), Johannes Schönbein (University of Freiburg)
'Flood Marker' in a subfossil oak tree from the River Rhine in the year 4893 BP, which verifies precipitation anomalies during the Holocene.
The project ‘HoloFlood’ will estimate precipitation dynamics on major periods of the Holocene. This will be done combining two unique, annually resolved climate archives: Documentary data back to 1.000 AD and tree-ring data back to 10.000 BP. We will derive information about past precipitation anomalies, resulting in river flow changes and extreme floods directly from tree rings. As proxies we use wood anatomical variables from exact dated subfossil oak tree rings, measured by a new semi-automatic image analysis technique to get information about the water status of the tree, and combine with direct information about long term flooding derived from wood anatomical anomalies of the same oak tree rings. That allow to reconstruct precipitation anomalies, river flow and extreme floods for the river systems Rhine, Main and Danube in Central Europe, from were we got continuous tree-ring chronologies of the Holocene. Time series for key climatic parameters will be modelled by applying transfer functions. The time series of air temperature, air pressure and precipitation from 1880 until 2007 will be analysed and Climate anomalies will be filtered out using fast Fourier transformation and stepwise regression and will be compared with data from recent tree-rings to figure out the signal of the anomalies. The climate-signal relation then will be validated during the last millennium (1000-1880 AD) by comparing to historical climate data. After this validation the signal of the ancient tree ring data will be transformed with the modelled data from the calibration and validation period into climate parameters with the main focus on precipitation anomalies. In the first stage we focus on two periods: The 8,2 ha BP period and 4650 BP, were a major hydrological change in the river valleys must be assumed from tree-ring data. The estimation of past precipitation variability during the Holocene will help to differentiate between anthropogenic and natural driving forces of observed climate variability and therefore will help to predict future climate changes.
Dendrochronology, quantitative wood anatomy, image analysis, dendroclimatology, historical climatology
Tree rings from subfossil and living oak trees, documentary data
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