Holocene Tropical Cyclone Activity in Northwestern Australia Recorded as Mud Layers in Stalagmites

April 14th, 2012

Tropical cyclones (a.k.a. hurricanes and typhoons) are among the most devastating forms of extreme weather events in terms of loss of life and destruction of property.  Identifying long-term trends in tropical cyclone activity is crucial to understanding the mechanisms that drive variability in frequency and intensity.  Historical records of cyclone activity are high-resolution, but short-reaching, making them ineffective as tools to identify trends that may only appear over multi-decadal to centennial timescales.  In the Kimberley Region of Western Australia, mud coatings of aragonite stalagmites deposited during flooding events of cave KNI-51 correspond, in the majority of cases, to rainfall associated with the passing of tropical cyclones close to the cave.  The fast-growing aragonite can be dated using radioisotopic U-series analysis to provide an extremely high-resolution (±1 year) growth model for the stalagmite KNI-51-F, which grew continuously from 924±3 BP until 387±1 BP.  Applying the growth model to the mud layers creates a multi-centennial record of cyclone activity in the area. This detailed record can be compared with trends in sea-surface temperature, insolation, the El Niño Southern Oscillation and mobility of the Inter-Tropical Convergence Zone to identify forcing mechanisms behind tropical cyclone activity.

Michael Barthelmes, ’13
Dodgeville, WI
Major: Geology                                                                                      

Sponsor: Rhawn Denniston

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