Combining meteorological and oceanic observations for an improved SODA: reconstrucing climate variability during the past century

海洋储存和输送热量和淡水的能力使其在气候变化中发挥着至关重要的作用。海洋可以隔离多余的热量，从而破坏大陆变暖趋势或改变降雨模式的想法是一个快速增长的研究文献的主题。许多关于间断的研究的观测基础大多限于2001年以来的几年，当时由于阿尔戈，海洋的仪器覆盖范围扩大了。气象学家们正在努力改进和扩大地面气象记录，使之追溯到世纪。本提案是一项补充性努力，旨在探索利用数据同化将联合收割机历史观测、地面气象学和海洋动力学结合起来重建海洋热量和水储存的相应记录的局限性。通过阐明历史海洋气候记录和历史数据采样对我们了解过去变化的限制，这项研究为预测和预测未来气候变化和变化提供了关键信息。所产生的海洋再分析数据集将免费提供给其他研究人员和一般社区，这将促进进一步的研究效益。这项工作也将形成马里兰州大学研究生论文的基础。人们日益认识到海洋和海冰系统在气候变异和变化方面发挥着关键作用，因此，最佳利用有限的历史记录必须成为高度优先事项。最近海洋变暖的中断似乎仅限于过去十年，但海洋从1970年开始经历了更长的二十年中断，可能在20世纪40年代和50年代又经历了一次。有人认为，1970年代加热的减少是气溶胶负荷增加对净表面加热的影响的结果。如果是这样的话，这应该会导致热量分布与最近的间断（太平洋气候变化可能很重要）之间的显着差异。20世纪40年代相对凉爽的北大西洋结束了北极前所未有的变暖时期。是否有证据表明向北输送到北极的热量相应减少？我们对盐度历史记录的理解甚至不如温度那么确定，但记录在案的海洋上层盐度趋势是否可以改变水团的通风？该提案将建立在PI长期开发的简单海洋数据同化（SODA）再分析的基础上，作为探索海洋在气候变化中的作用的工具。一个关键的重点将是使用观测系统模拟实验和数据保留实验，以探索这些重建的准确性，以更好地了解这种重建的应用范围。在一个混合集合数据同化系统中，结合使用水文和验潮站海平面数据，本提案将重新分析1900年至2015年的海洋和海冰变化（包括海平面），并使用观测系统实验来量化不确定性。这项工作的理由在于需要解决美国气候变率和可预测性（CLIVAR）计划的目标，即“描述和理解海洋在季节，年际和十年时间尺度上的气候变率中的作用”以及美国2012-2021年全球变化研究计划的建议。

The ocean's ability to store and transport heat and freshwater gives it a crucial role in climate variability. The idea that the ocean can sequester excess heat and thus disrupt continental warming trends or shift rainfall patterns is the subject of a rapidly growing research literature. Much of the observational basis for many studies of the hiatus is limited to the years since 2001 when the instrumental coverage of the oceans expanded due to Argo. An effort by meteorologists is refining and extending the surface meteorological record back to the nineteenth century. This proposal is a complementary effort to explore the limits of using data assimilation to combine historical observations, surface meteorology, and ocean dynamics to reconstruct the corresponding record of ocean heat and water storage. By elucidating the historical ocean climate record and the limits to what we can learn about past variability due to the historical data sampling this research provides a key piece of information for efforts to anticipate and predict future climate variability and change. The ocean reanalysis data sets produced will be made freely available to other researchers and the general community, which will foster further research benefits. This work will also form the basis of a dissertation for a University of Maryland graduate student.The ocean and sea ice systems are increasingly being recognized as playing a key role in climate variability and change and so making best use of the limited historical record must be a high priority. The recent hiatus in ocean warming seems to have been confined only to the past decade, but the oceans experienced a much more extended two decade hiatus beginning in 1970 and likely another in the 1940s and 1950s. It has been suggested that the reduced heating in the 1970s was the result of the effects of increasing aerosol loading on net surface heating. If so that should lead to significant differences in heat distribution from the recent hiatus (for which Pacific climate variability is likely important). The relatively cool North Atlantic of the 1940s ended a period of unprecedented warming of the Arctic. Is there evidence to suggest corresponding reductions of northward heat transport into the Arctic? Our understanding of the historical record of salinity is even less certain than temperature, but can the documented trends in upper ocean salinity be shown to alter the ventilation of water masses? The proposal will build on the PI's long term development of the Simple Ocean Data Assimilation (SODA) reanalysis as a tool to explore the ocean's role in climate variability. A key emphasis will be on using observing system simulation experiments and data withholding experiments to explore the accuracy of those reconstructions to better understand the limits of application of such a reconstruction. With the combined use of hydrographic and tide gauge sea level data together in a hybrid ensemble data assimilation system, this proposal is to reanalyze ocean and sea ice variability (including sea level) from 1900 through 2015, and to use observing system experiments to quantify uncertainties. Justification for the work lies in the need to address the US CLIVAR (Climate Variability and Predictability) program's objectives of "describing and understanding the ocean's role in climate variability on seasonal, interannual, and decadal timescales" and the recommendations of the U.S. Global Change Research Plan 2012-2021.