Browsing by Author "Wallace, Elizabeth J."

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    4500-year paleohurricane record from the Western Gulf of Mexico, Coastal Central TX, USA
    (Elsevier, 2024) Monica, Sarah B.; Wallace, Davin J.; Wallace, Elizabeth J.; Du, Xiaojing; Dee, Sylvia G.; Anderson, John B.
    Texas receives the second-highest number of tropical cyclone (TC) landfalls per year in the United States. At present, long-term TC projections from climate models remain uncertain due to the short and biased nature of Atlantic TC observations. Sediment archives of past storms can help extend the observational record of TC strikes over the past few millennia. When a TC makes landfall along the central Texas coast, coastal downwelling channels and storm currents transport and deposit coarse sediment to a zone of rapid accumulation along the shelf, known as the Texas Mud Blanket (TMB). This “backwash” process results in expansive storm deposits along the shelf, making this region ideal for paleotempestological reconstructions. Here, we present two sediment cores, located approximately 6 km southeast of Matagorda Island (TX), that collectively yield a ∼4500-year paleohurricane record. 210Pb and 137Cs are utilized in conjunction with radiocarbon ages to produce high-resolution Bayesian age models. One-centimeter interval grain size analyses are used to identify TC deposits. Two-centimeter interval X-Ray Fluorescence (XRF) is used as an additional measure to verify depositional mechanisms in this shelf environment. We define an intense paleohurricane event threshold through statistical analysis of mean grain size data. The sediment-derived TC record is correlated to Palmer Drought Severity Index (PDSI) data from Paleo Hydrodynamics Data Assimilation (PHYDA) to bolster our interpretation of the TC record, revealing a coupled relationship between PDSI and TCs since ∼300 yr BP. Over the ∼4500-year period, 24 intense TCs were recorded in the sediment record, yielding a long-term annual landfall probability of ∼0.53%. Additionally, comparisons between other TC records within the Atlantic establish a relationship between enhanced TC activity in the Western Gulf of Mexico (GOM) and TCs formed in the Caribbean Sea.
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    A Proxy System Modeling Approach to Combining Tree-Ring and Sediment-Based Paleotempestological Records
    (Wiley, 2024) Wallace, Elizabeth J.; Dee, Sylvia; Bregy, Joshua; Emanuel, Kerry A.
    The short and biased observational record of tropical cyclones (TCs) limits scientific understanding of how these destructive storms respond to climate forcing. Paleohurricane records use natural archives (tree rings, coarse-grained sediment) to reconstruct TC properties (frequency and intensity of rainfall, wind) over the past few hundreds to thousands of years. However, different sensitivities and sampling biases in the various paleohurricane proxies restrict our ability to compile these records into regional or basin-scale TC estimates. Here we test how well pseudo tree-ring records of paleohurricanes capture TC rainfall and occurrence. Using a large set of statistically downscaled storms forced with the Max Planck Institute (MPI-ESM-P) model as boundary conditions for the past millennium, we generate a 1000-member ensemble of pseudo tree-ring records of latewood width from southern Mississippi using a Poisson process-based random draw. Pseudo records convert synthetic TC rainfall into latewood width using a previously published statistical calibration and seasonal sensitivity. We show that fourth quantile thresholds applied to pseudo latewood data successfully identify years with TC strikes. Comparing pseudo tree-ring records with pseudo sediment records from the Gulf Coast indicates promise in combining proxies sensitive to TC rainfall with proxies sensitive to storm overwash. Sediment records that are sensitive to lower intensity storms (≥Saffir Simpson Category 1) are more compatible with tree-ring records, suggesting a need for more of these low intensity threshold records in the Gulf to facilitate future multi-proxy efforts to reconstruct past TC properties.