A Paleoclimatic Examination of Tropical Cyclone-Related Precipitation Variability and Atmospheric-Oceanic Controls Inferred from Longleaf Pine in the Coastal Carolinas

该项目将分析过去300年来影响北卡罗来纳州和南卡罗来纳州沿海地区的热带风暴和飓风等热带气旋造成的降雨量的变异性。由于对东南大西洋沿岸热带气旋降水的准确仪器记录仅从1950年左右到现在才存在，通过开展该项目改进的新方法将扩大对热带气旋降水和热带气旋频率长期变化的理解。初步研究表明，较长的热带气旋最小降雨期超过了以前确定的重复间隔，从而表明热带气旋降雨量的变化比最近经历的更大。虽然该项目侧重于卡罗莱纳州沿海的几个地点，但从得克萨斯州到北卡罗来纳州，在从得克萨斯州到北卡罗来纳州的登陆热带气旋范围内出现的长叶松树年轮中所载的替代记录，为扩大对热带气旋及其沿遥远东南大西洋和墨西哥湾海岸降水的长期变异性的基本了解提供了一个可行的手段。项目结果和方法对于将古气候与当前条件与观测到的洪涝和干旱事件的增加联系起来将具有价值。项目结果将与政府机构和其他团体分享。加强对热带气旋总降雨量变化的了解，将有助于规划人员和从事抗洪抗旱项目的管理人员。除了为研究生和本科生提供教育和培训机会外，参加北卡罗来纳州夏季科学和数学冒险项目的高三学生还将有机会了解该项目。热带气旋降水对地下水补给至关重要。它可以突然结束干旱，并发挥重要的生态作用。热带气旋降水还导致内陆洪灾，造成多人死亡、大范围停电和数十亿美元的损失。参与该项目的研究人员将开发一种方法来确定几个世纪以来热带气旋降水的变化。长叶松树的生长模式将用一种称为交叉测年的方法确定，热带气旋季节形成的年度晚材年轮宽度将被测量并与热带气旋降水的仪器气候记录进行统计匹配。研究人员将把热带气旋降水的记录延长200多年，而不是使用仪器记录。他们将记录热带气旋降水的长期时空变异性，并将审查热带气旋降水对气候变异性模式的双变量敏感性，例如北大西洋涛动和大西洋年代际振荡。他们还将确定这些大尺度大气模式对热带气旋降水的潜在相互作用和多变量影响。树木年轮数据将非破坏性地从活树和残存的树桩中收集。利用统计回归，数学模型将重建热带气旋降水量的历史总量。将使用基于回归和小波分析的技术来研究热带气旋降水的几个世纪的模式的趋势、周期性和体制变化。

This project will analyze the variability of rainfall resulting from tropical cyclones, such as tropical storms and hurricanes, that impacted the coastal regions of North Carolina and South Carolina during the last 300 years. Because an accurate instrumental record of precipitation from tropical cyclones along the southeastern Atlantic Coast exists only from about 1950 to the present, the new approach refined through the conduct of this project will expand the understanding of the long-term variability of tropical cyclone precipitation and tropical cyclone frequency. Preliminary research has indicated that longer periods of minimal tropical cyclone precipitation exceeded previously identified recurrence intervals, thereby indicating that the variability in tropical cyclone precipitation is greater than has been experienced recently. Although this project focuses on several sites in the coastal Carolinas, the proxy record contained in tree-rings of longleaf pine trees that occur throughout the range of land-falling tropical cyclones from Texas to North Carolina offers a viable means to expand basic understanding of the long-term variability of tropical cyclones and their precipitation along the far southeast Atlantic and Gulf coasts. Project findings and methods will have value for linking paleoclimates with current conditions with observed increases in both flooding and drought events. Project findings will be shared with governmental agencies and other groups. An enhanced understanding of variability in total precipitation volume from tropical cyclones will assist planners and management personnel engaged in flood- and drought-mitigation projects. In addition to providing education and training opportunities for graduate and undergraduate students, high school seniors engaged in North Carolina's Summer Ventures in Science and Mathematics program will have opportunities to learn about the project.Tropical cyclone precipitation is critical to groundwater recharge. It can abruptly end droughts, and it serves an important ecological role. Tropical cyclone precipitation also causes inland flooding resulting in multiple fatalities, widespread power outages, and billions of dollars in damages. The investigators engaged in this project will develop a method to determine variations in tropical cyclone precipitation for multiple centuries. The pattern of longleaf pine tree growth will be determined using a method called cross-dating, and the annual latewood ring width, which develops during tropical cyclone season, will be measured and statistically matched with the instrumental climate record of tropical cyclone precipitation. The investigators will extend the record of tropical cyclone precipitation more than 200 years beyond that available using the instrumental record. They will document long-term spatio-temporal variability of tropical cyclone precipitation, and they will examine the bivariate sensitivity of tropical cyclone precipitation to modes of climate variability, such as the North Atlantic Oscillation and Atlantic Multidecadal Oscillation. They also will determine the potential suite of interactive and multivariate influences of these large-scale atmospheric modes on tropical cyclone precipitation. Tree-ring data will be collected non-destructively from live trees and from remnant stumps. Using statistical regression, mathematical models will reconstruct the historical volume of tropical cyclone precipitation. Multi-century patterns of tropical cyclone precipitation will be examined for trends, periodicities, and regime shifts using regression-based and wavelet analysis techniques.