The climate-archive dune: Sedimentary record of annual wind intensity (southern North Sea)
Abstract
The understanding of the long-term variability of local wind-fields is most relevant for calibrating climate models and for prediction of the socio-economic consequences of climate change. Continuous instrumental-based weather observations go back less than two centuries. The geological record, however, contains an archive of past wind-field fluctuations which is basically unread. The sediment accumulations of eolian dunes are formed by wind, and deposited grain-size spectrum and sedimentary geometries are directly linked to local wind conditions during formation of these bodies. We show that active dunes bear a high-resolution archive of past wind strength. Variations in the grain-size spectrum of an active dune through time are compared with an observational based time series of wind speed. Annually averaged, proxy-derived wind intensity and instrumental record of wind speed show a correlation of up to 0.75. Our results demonstrate that the mean grain size of sediments deposited at the slipface of active dunes reflects past wind intensity, but they also emphasize the importance of a robust age model and good stratigraphic control. In general, proxy formation is afflicted with a certain bias and prone to long-lasting wind conditions rather than (storm-) events. Applied to reconstruct 20th century variations of wind intensity in the southern North Sea, the study demonstrates the potential of eolian dunes to gain long-term proxy-based data series of wind intensity in areas and for time periods lacking instrumental observations. The approach can be applied to recent as well as fossil dunes. Potential applications include the validation of climate models, the reconstruction of past supra-regional wind systems and the monitoring of future shifts in the climate system.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMEP21A0857L
- Keywords:
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- 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSESDE: 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 1625 Geomorphology and weathering;
- GLOBAL CHANGEDE: 1809 Desertification;
- HYDROLOGY