RUI: High-resolution sediment records of late Holocene paleohydrology from the summer and winter rainfall regions of South Africa.

RUI：南非夏季和冬季降雨地区全新世晚期古水文学的高分辨率沉积物记录。

• 批准号: 0822922
• 负责人: Jay Stager
• 金额: $ 33.42万
• 依托单位: Paul Smith's College of Arts and Sciences
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0822922&HistoricalAwards=false
• 关键词: RUI; resolution; sediment; records; late

Paleoclimatic research in Africa has relied heavily upon analysis of lake sediment cores and has provided abundant evidence of dramatic climate fluctuations during the late Quaternary. However, much of that work has suffered from several important limitations, including (1) coarse temporal resolution of time series, (2) gaps due to discontinuous sedimentation or loss of soft upper sediments during coring, (3) complications in sediment dating, (4) a scarcity of continuous lake records from the southern hemisphere, and (5) difficulty in teasing out the relative contributions of rainfall and temperature to inferred environmental changes. These limitations have reduced the clarity of climate reconstructions and hindered the development of robust regional and global-scale models of rainfall dynamics, especially for the late Holocene.Under this RUI grant, the PI and undergraduate students analyze diatoms (algae with glassy shells) and geochemical records in lake sediment cores representing the last 2000 years that were recently collected in South Africa in collaboration with American and African students and colleagues. These cores represent key sites in the southern summer and winter rainfall regions of the continent and they contain clear evidence of paleohydrological fluctuations. The central goal is to clarify the nature and causes of African rainfall variability during the late Holocene.Intellectual merit: The fine temporal resolution of these analyses, conducted at annual to decadal increments and dated with 14C, 210Pb, 137Cs, and pollen indicators is unusually high for African cores. These detailed time series help to refine the nature and timing of key paleoclimate events in southern Africa in relation to records from equatorial and polar latitudes. They also provide continuous paleohydrological records leading into modern times, and help to clarify the interpretations of pollen- and isotope-based studies in the region. These findings are used to evaluate models of rainy season responses to past global warmings and coolings, of African-Antarctic teleconnections, and of solar influences on African rainfall during the last two millennia. Transfer functions are used to convert diatom data into the longest and most detailed reconstructions of Holocene water chemistry parameters that have ever been obtained in South Africa. Results are compared to other records ranging from equatorial to polar latitudes, putting the climatic history of South Africa into a global context.Broader impacts: Rainfall has much greater ecological and societal impacts in Africa than temperature alone does. By clarifying the recent hydrological history of South Africa, this study supports efforts to model and predict rainfall dynamics, as well as the roles of Antarctic and solar influences (and, indirectly, greenhouse warming) in relation to past and future African climate changes. Two undergraduate students are helping to collect and analyze cores for their senior capstone projects at Paul Smith's, a small college in an under-served rural region of upstate New York. Collaborations with paleoecologists in South Africa and Britain enhances PI and student access to research facilities, professional networks, and expertise, and the data is archived at the NOAA World Data Center. The internationally syndicated "Natural Selections" radio program broadcasts the results of this work widely and also makes podcasts available from the North Country Public Radio website.

非洲的古气候研究在很大程度上依赖对湖泊沉积物岩心的分析，并提供了大量在第四纪晚期的气候波动的证据。但是，这项工作的大部分遭受了几个重要的局限性，包括（1）由于不连续的沉积物或加油过程中柔软的上沉积物的不连续沉积物或柔软的上沉积物的损失，（3）沉积物日期的并发症，（4）偏离南半球的连续湖泊记录的稀缺以及（5）在偏离环境中的偏离环境中的差异和（5）相对温度的变化。这些局限性降低了气候重建的清晰度，并阻碍了降雨动态的强大区域和全球尺度模型的发展，尤其是对于晚期全新世。 同事。这些核心代表了大陆南部夏季和冬季降雨区域的关键地点，它们包含清晰的古水学波动证据。核心目标是阐明晚期全新世期间非洲降雨变异性的性质和原因。智能优点：这些分析的良好时间分辨率，每年以每年至十年的增量进行进行，并以14C，210pb，137cs，137cs和花粉指标的日期为非洲岩心的高度高。这些详细的时间序列有助于完善南部非洲关键古气候事件的性质和时机，与赤道和极地纬度的记录有关。他们还提供了通向现代的连续古水记录，并有助于阐明该地区基于花粉和同位素研究的解释。这些发现用于评估过去两千年来，对过去的全球变暖和冷却，非洲 - 北极遥相关的反应，非洲 - 北极遥相关以及太阳影响非洲降雨的影响。转移功能用于将硅藻数据转换为南非有史以来全新世水化学参数的最长，最详细的重建。将结果与从赤道到极地纬度的其他记录进行了比较，这使南非的气候历史成为全球环境。BROADER的影响：降雨在非洲的生态和社会影响要比单独温度更大。通过阐明南非最近的水文历史，这项研究支持努力建模和预测降雨动态，以及与过去和未来的非洲气候变化有关的南极和太阳影响（以及间接的温室变暖）的作用。两名本科生正在帮助收集和分析核心在纽约州北部地区一所农村地区的一所小型大学保罗·史密斯（Paul Smith's）的高级顶峰项目。与南非和英国的古生物学家的合作可增强PI和学生对研究设施，专业网络和专业知识的访问，并且数据在NOAA世界数据中心进行了存档。国际联合的“自然选择”广播节目广播了这项工作的结果，还可以从北国公共广播网站上提供播客。