Please join us for the next CILER-GLERL Great Lakes seminar!
Title: Potential forcing variables that drive coastal dune evolution along the eastern shore of Lake Michigan: Does hemispheric ENSO Cycling also play a role?
Time: 10:30-11:30 EST
Location: NOAA Great Lakes Environmental Research Lab, Lake Superior Hall, 4840 S. State Rd. Ann Arbor, MI 48108
**Registration is not required, however please note important visitor information**
Abstract: The chronology of coastal dune evolution along Lake Michigan has been the focus of intensive research for the past 20 years. Although early studies associated episodes of dune growth to high lake stages, this relationship remains unclear, as do the potential roles of storminess and atmospheric circulatory processes. We refined the record and association with potential forcing variables through a statistical synthesis of the > 250 14C and optical dates reported thus far. A probability density distribution (PDD) demonstrates that seven major cycles of dune growth occurred in the past 5,500 years. Five periods of dune growth transpired during lake transgressions, whereas two occurred during lake regressions. Intervals of dune growth may also be related to hemispheric atmospheric circulatory patterns associated with the reconstructed history of ENSO (El Niño/LaNiña) cycling in the eastern Pacific. Episodic growth of dunes between about 4,500 and 2,000 years ago correlates well with the highly variable frequency and amplitude of El Niño and La Niña events, respectively. Extended coastal dune stability between 2,000 and 1,000 years ago is closely associated with a significant decrease in ENSO activity. These associations suggest a linkage between lake-level fluctuations, sand supply, and storminess. Our model is supported by 1) the dominant temporal correlation of dune activation with transgressive lake phases associated with higher basin input and 2) the dominant southwesterly orientation of > 1,200 parabolic dunes, suggesting they mobilized in the late autumn and early winter when the strongest modern winds occur in association with deep cyclones lifting out of the south-central Great Plains. These findings suggest that intense intervals of coastal dune building in the Great Lakes region are not related to any single factor, but rather the cyclic convergence of several forcing variables, some of which are hemispheric in nature.
**Important Visitor Information**
All in person seminar attendees are required to receive a visitor badge from the front desk at the NOAA Great Lakes Environmental Research Laboratory facility. Seminar attendees need to present a valid U.S. photo ID or green card. If you are a Foreign National advance notification of at least 48 hours is needed so that security guidelines are followed. You will need to present your passport (a copy will NOT work). For questions regarding building access, or assistance in obtaining Foreign National clearance, please call 734-741-2235. Email contact: Tim.Powell@noaa.gov
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