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
Sponsor: Rhawn Denniston