NSF Award
2216182
Tropical cyclones, also called typhoons or hurricanes, are intense storms that form over warm tropical oceans. They can cause damage to buildings and even loss of life. The western North Pacific is the location of the most tropical cyclones with an average of 40 storms per year. However, instruments that record tropical cyclones have only existed for about 75 years. This project will acquire sedimentary records across multiple sites that will be used to document tropical cyclone activity for the last several thousand years in the western North Pacific. Results will be important for understanding climate factors that control tropical cyclone frequency and intensity. Broader impacts include support for undergraduate and graduate students and educational outreach activities in the U.S. and Philippines.<br/><br/>Coarse-grained storm-induced deposits, preserved in coastal sedimentary basins, are particularly effective proxies for intense tropical cyclone impacts at a site. Previously published work and preliminary data show that deep coastal depressions with rapidly accumulating sediments contain high-resolution records of the passage of intense tropical cyclones. However, few such long-term sedimentary records have been developed thus far in the western North Pacific. This project will collect seismic, multibeam, and sediment core data for sites across the Philippines, Palau, Guam, Chuuk, Pohnpei, and Kosrae in the western North Pacific. Collected sediment cores will be analyzed using a multi-proxy approach consisting of coarse fraction and grain-size distribution measurements, loss on ignition analysis, radiography and elemental analysis via X-ray fluorescence scanning, sediment petrography, microfossil and macrofossil analysis, and computed tomography. Modern sedimentary analogs will also be analyzed. Cores will be dated using a multi-proxy approach based on short-lived isotopes and radiocarbon ages using a Bayesian statistical framework. These millennial-scale reconstructions will provide a means of extending documentary records of tropical cyclone strikes back millennia and allow for i) the examination of climate/tropical cyclone interactions that lack modern analogs, ii) the generation of more accurate reoccurrence rate estimates, and iii) assessment of variations in storm activity on sub-millennial time scales. The results of this work will provide essential data on past patterns of tropical cyclone activity in the western North Pacific and offer broader insight into climate factors that modulate tropical cyclone frequency, intensity, track, and area of development.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
