Collaborative Research: Beyond the Instrumental Record---The Ocean Circulation at the Last Glacial Maximum and the Deglacial sequence

该项目旨在定量了解末次冰期最大期的海洋环流，在此期间，气候与今天的状况截然不同，海洋的表现也与今天大不相同。核心方法是将一个被认为在现代世界中有用的海洋环流模式与北大西洋末次盛冰期的古海洋学代用数据结合起来，联合收割机。结合两者的数值技术是基于最小二乘法的拉格朗日乘子实现使用伴随模型。代理数据将根据相对误差的最佳估计单独加权。海洋状态的计算涉及调整“第一次猜测”的初始和边界条件，然后修改这些条件以减少模型-代理-数据的不匹配。最丰富的有用的代用数据包括同位素氧和碳，推断孔隙水盐度和各种海面温度重建。估计数将是一个假定的永久年周期。支持工作是针对推论，主要是全球性的，在现代海洋的环流特性，可以最容易地比较到更不受约束的末次冰期最大时期。智力优点：在一个层面上，海洋环流的确定是一个基本的知识挑战，在地球科学-除了任何实际应用。在现代世界中，即使有相对较大的数据集，也很难确定。末次盛冰期的环流提出了一个更大的智力挑战，因为它依赖于间接数据集（称为“代理”），而且在空间和时间上都很稀疏。除了这一科学好奇心方面，海洋被广泛认为是决定过去和未来气候状态的主要贡献者，这些气候状态与现在截然不同。只要末次盛冰期期间的海洋状态仍然像现在这样模糊不清，就很难声称理解气候系统是如何运作的，而且随着人类强迫的增加，它将破坏对未来可能带来的影响的预测。这个项目是一个广泛的社区努力的一部分，旨在了解过去发生的非常不同的气候状态，包括完整的冰川期和基本上没有冰的时期。人们普遍认为，海洋在产生这些不同的状态和/或维持它们很长一段时间方面的影响非常重要，但人们对此知之甚少。这项工作是独一无二的，试图了解海洋的最后一次冰期最大的充分定量使用所有的代理数据加上一个一般的环流模型，认为可以很好地描述现代世界。这种方法可以用于冰消期以及过去的其他间隔，也许是间冰期，在那里有足够的数据。大多数拟议的研究将由一名研究生完成，作为她博士学位的一部分。论文

This project is directed at a quantitative understanding of the ocean circulation during the last glacial maximum, a period during which the climate was a radically different state from today with an ocean inferred to also have behaved quite differently. The central approach is to combine an ocean general circulation model found to be useful in the modern world, with the paleo-oceanographic proxy data for the North Atlantic during the last glacial maximum. The numerical technique for combining the two is based upon the least squared method of Lagrange multipliers as implemented using an adjoint model. Proxy data will be individually weighted according to best estimates of the relative errors. Calculation of the oceanic state involves adjusting "first-guess" initial and boundary conditions that are then modified to reduce the model-proxy-data misfits. The most abundant useful proxy data include isotopic oxygen and carbon, inferred pore water salinities and various sea surface temperature reconstructions. Estimates will be of an assumed perpetual yearly cycle. Supporting work is directed at inferences, mainly global ones, of circulation properties in the modern ocean that can most readily be compared to the much more poorly constrained last glacial maximum period.Intellectual Merit: At one level, determination of the ocean circulation is a fundamental intellectual challenge in the earth sciences - apart from any practical applications. Determination in the modern world is very difficult, even given the comparatively large data sets available. The circulation of the last glacial maximum presents a far greater intellectual challenge, dependent as it is on indirect data sets (called "proxies") and which are sparse in space and time. In addition to this scientific curiosity aspect, the ocean is widely regarded as a major contributor in determining past and future climate states differing radically from the present one. As long as the oceanic state during the last glacial maximum remains as obscure as it is, it will be extremely difficult to claim understanding how the climate system works, and it will undermine predictions of what the future might bring as anthropogenic forcing increases.Broader Impacts: This project is a part of a wide community effort aimed at understanding the very different climate state known to have occurred in the past, including periods of full glaciation and ones of essentially no ice. A consensus exists that the influence of the ocean in bring about these different states and/or sustaining them for extended periods of time is very important, but extremely poorly understood. This effort is unique in attempting to understand the ocean of the last glacial maximum by the fully quantitative use of all the proxy data plus a general circulation model thought to well describe the modern world. With a successfully outcome, this approach could be used to the deglacial periods as well as other intervals in the past, perhaps inter-glacial, where an adequate data exists. Most to the proposed research will be done by a graduate student as part of her Ph.D. thesis.