| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | July 24, 2012 |
| Latest Amendment Date: | June 12, 2013 |
| Award Number: | 1144869 |
| Award Instrument: | Fellowship Award |
| Program Manager: |
Lina Patino
lpatino@nsf.gov (703)292-5047 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | August 1, 2012 |
| End Date: | August 31, 2015 (Estimated) |
| Total Intended Award Amount: | $85,000.00 |
| Total Awarded Amount to Date: | $127,500.00 |
| Funds Obligated to Date: |
FY 2013 = $42,500.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
Houston TX US 77005-1892 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
TX US 77005-1892 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Postdoctoral Fellowships |
| Primary Program Source: |
01001314DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Dr. Davin Wallace has been granted an NSF EAR Postdoctoral Fellowship to conduct research and develop an integrated educational plan at the University of Massachusetts at Amherst and Woods Hole Oceanographic Institution/MIT. He will investigate hurricane impacts over the past 10,000 years in the western Atlantic basin by conducting a paleotempestological study on the island of Bermuda. During modern times, the historic record tells us that a significant amount of Atlantic hurricanes recurve basin ward and never make landfall on coastlines, with the exception of Bermuda. Previous paleohurricane studies have been located along the Gulf of Mexico, Caribbean Sea, and Atlantic Oceans, and the addition of this site would therefore shed light on the total paleohurricane frequency in the western Atlantic Basin over the Holocene. Dr. Wallace will collect sediment cores in several coastal ponds and analyze them for grain size variations, as coarse sediment represents storm-induced transport from nearby beaches. To establish an accurate chronology of these events, he will analyze these cores using radiocarbon and short-lived isotope analyses. Finally, he will model both the paleointensities of each event and the response of hurricanes to past climate variations.
Each year, hurricanes annually impact Gulf of Mexico, Caribbean, and Atlantic coastlines. However, we have only a short reliable historical record of hurricane impacts. By understanding the interaction between paleohurricanes and past known climate changes over the western Atlantic Basin, we can use this information to predict hurricane formations and impacts in the future. Also, establishing a long-term hurricane record for the western Atlantic will help bridge the gap between field and modeling based paleoclimate studies, as models become better calibrated with additional data. Further, this work can be used to interpret changes over historic time in the context of a longer geologic record. Dr. Wallace will participate in the Woods Hole Oceanographic Institution Sea Grant program, in addition to leading several workshops for K-12 educators for this group. This outreach effort will focus on activities and learning approaches associated with the results of this project. He will also participate in videoconferences with a group of science teachers in a cohort of teachers from Texas to discuss this work.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Due to short historical records, our understanding of hurricanes is currently incomplete. While some trends have been analyzed and determined from the instrumental data available, questions remain concerning potential biases in this record due to increasing observational capacity. Lengthening the reliable hurricane record therefore remains of the utmost importance.
Paleohurricane records can be a useful tool for extending these instrumental observations and accurately connecting storm response to climatic and oceanographic variations. Many such sites exist around the world, and carefully selected new sites can provide a more comprehensive understanding of global hurricane trends. This project funded a critical new paleotempestological site from Mangrove Lake, Bermuda. This site is perhaps the only subaerial location consistently impacted by Atlantic northeastward recurving storms, so its inclusion towards estimates of total Atlantic basin activity through time is critical.
Mangrove Lake is currently separated from the ocean by stable Pleistocene-age eolianites reaching 7 meters in height, so a storm inundating the area would need to exceed this threshold. Storms capable of marine deposition in the lake therefore represent large inundation events, preserved in the sedimentary record as coarse-grained deposits. These coarse-grained deposits contain the offshore foraminifera Homotrema rubrum, which is diagnostic of storm-induced transport in our setting.
In order to provide adequate chronological constraints for identified paleohurricane deposits, we obtained nearly 30 rapid turn-around gas ion source AMS radiocarbon dates, 4 conventional AMS ages, and short-lived isotopic data. The results of these analyses were input to construct a Bayesian statistical age-depth model. Two historic storms (category 4 events in C.E. 1939 and C.E. 1926) were the only modern events to leave a deposit, confirming the intense flooding threshold necessary for deposition. Similar flooding magnitude paleohurricanes were identified using these modern analogues from the sedimentary record on the basis of X-radiographs, X-ray fluorescence, micropaleontology, and grain size measurements to produce a ~2,000 year record of intense storms impacting Bermuda. Periods of frequent intense storms likely occurred between C.E. 1939 to 1,000 yr B.P., while inactive intense storm periods occurred between ~1,000 to 1,800 yr B.P. in addition to C.E. 1939 to present.
Intellectual Merit
Efforts are made annually to accurately forecast hurricane frequency and intensity. However, meteorological models yield little success in their ability to predict these trends, in part due to a reliance on a very short historical record of known storms. This work has provided an additional dataset to better understand long-term hurricane tracks, frequency, and intensity for the western Atlantic basin. From this information, hurricane variability can shed light on the response to climatic shifts. Ultimately, our knowledge is advanced through the ability to better predict and understand modern storm variability.
Broader Impacts
United States coastlines are especially vulnerable to hurricanes and are impacted annually. These coastal areas also represent some of the most populated, consistently growing areas. Atlantic hurricane impacts have resulted in significant life and economic loss. Hurricanes Katrina (2005), Wilma (2005), Andrew (1992), and Sandy (2012)...
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