Bispectral Analysis of Nonlinear Couplings Within the Geologic Record of Global Climate Change

全球气候变化地质记录中非线性耦合的双谱分析

• 批准号: 9012270
• 负责人: Nicklas Pisias
• 金额: $ 7.75万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-02-01 至 1993-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9012270&HistoricalAwards=false
• 关键词: Bispectral; Analysis; Nonlinear; Couplings; Within

A major finding 15 years ago was that various oceanographic parameters respond to orbital ("Milankovich") forcings in a linear manner. This means that 1) marine sediments faithfully record the frequencies of orbital patterns, shifted only in amplitude and phase; 2) interaction of the several known orbital frequencies results in marine patterns that are the sum of all these frequencies. The P.I. has recently discovered that Pliocene sediments from the eastern equatorial Pacific (DSDP) Site 572) show non-linear couplings to the Milankovich band. This means that the marinere cord shows evidence of: 1) harmonic distortion, i.e. orbital frequency fO is recorded at fO,2fO,3fO, etc,; 2) intermodulation distortion, i.e. various orbital frequencies both add and subtract to give a complex array of frequencies in the marine record. Funds have been awarded to expand this search for non- linear responses. Because commonly used techniques of time series analysis cannot detect anything other than linear response signals, bispectrum analysis and auto regressive moving average models will be explored as alternative techniques. Sensitivity studies will be conducted, and the final techniques will be applied to the analysis of any of several candidate ODP and DSDP records, using delta O18, delta C13, CaCO3, SST, eolian dust of magnetic susceptibility as the parameter to examine for orbital forcings.

15年前的一项主要发现是，各种海洋学参数对轨道(“米兰科维奇”)作用力的响应是线性的。这意味着1)海洋沉积物忠实地记录了轨道模式的频率，仅在幅度和相位上移动；2)几个已知轨道频率的相互作用导致海洋模式是所有这些频率的总和。P.I.最近发现，来自东赤道太平洋(DSDP)572站的上新世沉积物显示出与米兰科维奇带的非线性耦合。这意味着，海洋绳索显示出以下证据：1)谐波失真，即轨道频率fo记录在fo、2fo、3fo等处；2)互调失真，即各种轨道频率相加和相减，得到海洋记录中的复杂频率阵列。已拨出资金，以扩大对非线性响应的这一研究。由于常用的时间序列分析技术只能检测线性响应信号，因此将探索双谱分析和自回归移动平均模型作为替代技术。将进行敏感性研究，最后的技术将用于分析若干个候选的ODP值和DSDP记录中的任何一个，使用Delta O18、Delta C13、CaCO3、SST、磁化率的风尘作为检查轨道作用力的参数。