Doctoral Dissertation Research: Tree-Rings, Climate, and History in Central Mexico

这项研究将使用来自墨西哥的新的树木年轮年表，结合历史记录来重建极端干旱/潮湿事件的历史，并检查它们对墨西哥中部过去300至500年的环境和社会的影响。对墨西哥中部最近发展起来的树木年轮年表的初步分析表明，那里的树木生长受到干旱等极端气候事件的强烈影响。在树木年轮记录中，有几个异常生长不良的时期与干旱导致的作物歉收、饥荒以及随之而来的墨西哥中部社会混乱相吻合。该项目的主要目标将是开发墨西哥中部降水的第一个可靠的树木年轮重建，并使用这些数据来验证和量化极端气候和相关社会环境影响的历史记录。将查阅各种主要和次要历史记录，包括来自墨西哥城国家档案馆的记录。该项目的另一个目标是重建墨西哥中南部季风开始的时间，并检查季风季节异常早或晚的后果。降雨的时间和季节分布是影响墨西哥中部作物生产的一个重要因素，我们的一些新的树木年轮年表与北美季风系统的开始日期有很好的相关性。降水重建将利用墨西哥中部的单个和区域平均树木年轮年表与当地和区域尺度的降水数据之间的传递函数进行。季风开始日期的重建将利用墨西哥完整的树木年轮年表网络，得出树木年轮记录与开始日期之间的最佳关系。季风开始日期将使用日降水数据的阈值分析来确定。墨西哥中部是地球上人口最多的地区之一。利用树木年轮和其他环境数据重建的过去气候表明，墨西哥北部和美国西南部在过去500至1000年间经历了极端的气候波动。关于气候对墨西哥中部农业和社会的影响，有大量的历史文献。但是，长期的、对气候敏感的树木年轮记录在此之前是无法获得的。降水和季风发生的树木年轮重建将为研究墨西哥过去的气候及其对生态系统和社会的影响提供新的环境记录。这项研究的结果将通过会议报告和期刊以及向国家地球物理数据中心的国际树木年轮数据库提供资料来传播。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

This research will use new tree-ring chronologies from Mexico in conjunction with historical records to reconstruct the history of extreme drought/wetness events and examine their impact on the environment and society in central Mexico for the last 300 to 500 years. Initial analyses of recently developed tree-ring chronologies from central Mexico indicate that tree growth there is strongly influenced by extreme climatic events such as drought. Several periods of abnormally poor growth apparent in the tree-ring record are coincident with drought-induced crop failures, famine, and attendant social disruption in central Mexico. The primary objective of this project will be to develop the first robust tree-ring reconstructions of precipitation in central Mexico, and use this data to validate and quantify historical records of extreme climate and related socio-environmental impacts. A variety of primary and secondary historical records will be consulted, including records from the Archivo General de la Nacion in Mexico City. Another objective of this project will be to reconstruct the timing of monsoon onset in central-southern Mexico and examine the consequences of abnormally early or late monsoon seasons. The timing and seasonal distribution of rainfall is an important factor in crop production in central Mexico, and several of our new tree-ring chronologies are well correlated with the onset date of the North American Monsoon System. The precipitation reconstructions will be developed using transfer functions between individual and regionally averaged tree-ring chronologies from central Mexico and precipitation data at both local and regional scales. The reconstruction of monsoon onset date will utilize the complete network of tree-ring chronologies in Mexico to derive the best relationship between the tree-ring record and onset date. Monsoon onset date will be determined using threshold analysis of daily precipitation data.Central Mexico is one of the most populous regions on earth. Reconstructions of past climate using tree-rings and other environmental data indicate that northern Mexico and the southwestern United States have experienced extreme climate fluctuations over the past 500 to 1000 years. There is an extensive body of historical documentation regarding the impact of climate on agriculture and society in central Mexico. But long, climate-sensitive tree-ring records have previously not been available for this region. The tree-ring reconstructions of precipitation and monsoon onset will represent new environmental records for the study of past climate and its impact on ecosystems and society in Mexico. The results of this research will be disseminated through conference presentations and journals, and by contribution to the International Tree-Ring Data Bank at the National Geophysical Data Center. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.