Glacial-Interglacial Change in California Current System Dynamics: A New Alkenone Perspective

加利福尼亚海流系统(CCS)是最近几项研究的背景，这些研究侧重于北美和北太平洋冰川/间冰期气候变化的机制和影响，使用烯酮生物标志物的不饱和模式作为年平均海表面温度(SST)的替代。然而，CCS也是一个已知上升流发生戏剧性变化的环境，以响应这些SST替代记录被用来重建的气候变化。知道浮游植物的季节和深度分布，包括烯酮生产者，可能在很大程度上取决于营养状况，这一事实可能会对解释加州边缘向下的基于烯酮的SST记录产生什么影响？俄勒冈州立大学的研究人员假设，在冰川时期，沿东北太平洋边缘的上升流行为和养分输入的变化形成了SST替代记录，从而形成了研究界目前对北太平洋气候如何响应外部强迫的理解。研究人员将测量现代东北太平洋边缘沉积物中的烯酮不饱和模式和氢同位素组成，以追踪营养胁迫对输出到海底的烯酮信号的影响。然后将对同一地区最后一次冰盛期的沉积物进行测量，并在上一次完整的冰川周期中以大约4000年的分辨率在三个代表性地点进行测量。通过比较结果中的纬度趋势，研究人员将检验他们的假设，即通过CCS的冰川历史，烯酮的生产模式发生了重大变化。如果证明了这一点，该地区的古温度记录可以从这一改善的生态背景中受益于重新评估。从这些化石特征中得出的关于北太平洋气候和CCS强度之间关系的现有概念可能会得到改进。该项目的最佳概括是，努力解决围绕北美/北太平洋气候变化机制和时间的重要悬而未决的问题，同时评估一种强大的新古生态示踪剂的效用。在科学界试图确定最近异常的CCS上升季的重要性及其与北太平洋目前不断变化的大气状况的联系时，对这些关系的基本了解具有直接的重要性。资助将支持一名高级研究生，他一直在集中参与开发本研究项目所基于的想法。

The California Current System (CCS) is a setting where several recent studies, focusing on the mechanisms and effects of glacial/interglacial climate change in North America and the North Pacific Ocean, employ the unsaturation patterns of alkenone biomarkers as a proxy for mean annual sea surface temperature (SST). However, the CCS is also a setting where dramatic changes in upwelling are known to occur in response to the very climate variation that these SST proxy records are employed to reconstruct. Knowing that the seasonal and depth distribution of phytoplankton, including alkenone producers, can depend heavily on the nutrient regime, what ramifications might this fact hold for interpretation of down core alkenone based SST records along the California margin? The investigators at Oregon State University hypothesize that changes in upwelling behavior and nutrient input along the northeast Pacific margin during glacial periods have shaped the SST proxy record and, thus, the research community's current understanding of how North Pacific climate responds to external forcing. The investigators will measure alkenone unsaturation patterns and hydrogen isotopic composition in sediments from the modern northeast Pacific margin to track the effects of nutrient stress on the alkenone signal exported to the sea floor. Measurements will then be made on sediments from the same region at the last glacial maximum, as well as with roughly 4,000-year resolution at three representative sites through the last full glacial cycle. Through comparison of latitudinal trends in the results, the investigators will test their hypothesis that significant shifts occurred in the pattern of alkenone production through the glacial history of the CCS. If demonstrated, paleotemperature records from this region can be re-evaluated with the benefit of this improved ecological context. Current conceptions of the relationship between North Pacific climate and CCS strength, drawn from these fossil signatures, may be refined. This project is best summarized as an effort to resolve important open questions surrounding the mechanisms and timing of North American/North Pacific climate change while simultaneously evaluating the utility of a powerful new tracer of paleo ecology. Fundamental understanding of these relationships is of direct importance as the scientific community attempts to determine the significance of recent anomalous CCS upwelling seasons and their ties to the currently changing atmospheric conditions in the North Pacific. Funding will support an advanced graduate student who has been centrally involved in developing the ideas upon which this research project is based.