SODA4: ocean climate variability at mesoscale resolution

海洋观测是稀疏的，在空间或时间上分布不均匀。由于许多分析受益于规则网格上的完整场，因此开发了再分析产品来通过使用可用观测值约束数值模式来填补这一空白。使用最广泛的海洋再分析产品之一是简单海洋数据同化。它目前的版本(SODA3)没有足够的分辨率来捕捉大多数涡旋，特别是在高纬度地区。这可能会在存在强烈涡旋活动或风力强迫和混合的地区造成偏差。该项目利用计算能力的增长，利用一个模式更好地利用有限的历史观测记录，该模式解决了主要的较小运动尺度，以便产生一个称为SODA4的中尺度全球海洋/海冰再分析。该项目还包括重点审查中尺度过程在北极和亚极地/北极交换中的作用。这项工作旨在了解海洋和海冰系统在调节和改变地球天气和气候方面所起的作用，部分是作为改进对未来变化的预测的指南。对历史海洋变异性的更好理解有利于科学事业，因为它在改进耦合气候变异性预报方面发挥了关键作用，并通过重建盆地规模的背景为历史观测记录增加了额外价值。通过支持过去40年更符合实际的历史气候重新分析的发展和分布，该项目可以整合跨多个领域和学科的研究活动。更好地表示较小的运动尺度和诸如近岸环境等对人类影响较大的区域，也应有助于向广大社区(沿海规划者和工程师、风力发电场、渔业界等)提供信息。关于海洋的历史变异性和变化。这项研究项目还在几个方面服务于马里兰大学学院公园的教育使命。最直接的是，它将支持大气和海洋科学系一名研究生的论文研究。它还将涉及一些本科生研究项目。对SODA3结果的检验表明，当中尺度变率和近地表潜伏期过程占主导地位时，它的分辨率是不够的。该项目探讨了对海洋/海冰系统状态表示的进一步改进，即使在没有中尺度分辨率观测系统的几十年期间，也可以通过更完整地表示海洋中尺度过程来获得这些改进。将受益于分辨率提高的一个区域是北冰洋及其与亚极地涡旋的连接。亚极地北大西洋是与北冰洋交换水的主要途径，这一连接具有特殊的意义，原因有很多。首先，北欧海域的地表水正在迅速变暖，冬季冰层正在消退。其次，北极中部存在着强烈的年代际温度变率，后果未知。第三，它是深水形成的关键区域。因此，该项目包括一项重点工作，以改进亚极地/北极交换的动态及其与变化的北冰洋水团的联系的表现和诊断。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Oceanographic observations are sparse and not uniformly distributed over space or time. Since many analyses benefit from complete fields available over a regular grid, reanalysis products have been developed to fill this gap by constraining a numerical model with available observations. One of the most widely used ocean reanalysis products is the Simple Ocean Data Assimilation. Its current version (SODA3) does not have sufficient resolution to capture most of the eddies, especially in the high latitude regions. This may cause biases in regions where strong eddy activity or wind forcing and mixing are present. This project exploits the growth of computational power to make improved use of the limited historical observational record using a model that resolves the dominant smaller scales of motion in order to produce a mesoscale resolving global ocean/sea ice reanalysis called SODA4. The project also includes a focused examination of the role of mesoscale processes in the Arctic and in subpolar/Arctic exchanges. This work is directed toward understanding the role the ocean and sea ice systems play in regulating and modifying Earth’s weather and climate partly as a guide to improve forecasts of future changes. Improved understanding of historical ocean variability benefits the scientific enterprise by playing a crucial role as a guide to improve forecasts of coupled climate variability and by adding additional value to the historical observational record by reconstructing their basin-scale context. By supporting development and distribution of more realistic historical climate reanalysis spanning the past four decades this project can serve to integrate research activities across multiple areas and disciplines. The improved representation of smaller scales of motion and of regions of high human impact such as the nearshore environment should also help inform a broad community (coastal planners and engineers, wind farms, the fisheries community, etc.) regarding historical ocean variability and change. This research project also serves educational mission of University of Maryland College Park in several ways. Most directly it will support the dissertation research of a graduate student at the Department of Atmospheric and Oceanic Science. It will also involve a number of undergraduate research projects.Examination of SODA3 results shows that its resolution is insufficient where mesoscale variability and near-surface diapycnic processes play dominant roles. This project explores the additional improvements to representation of the state of the ocean/sea ice system that can be gained by more completely representing oceanic mesoscale processes even during decades when mesoscale-resolving observing systems were not available. One region which will benefit from enhanced resolution is the Arctic Ocean and its connection to the subpolar gyres. The subpolar North Atlantic is the major route by which water is exchanged with the Arctic Ocean and this connection is of particular interest for many reasons. First, the surface water of the Nordic Seas is warming rapidly and the winter ice is retreating. Second, strong decadal temperature variability is present with unknown consequences for the central Arctic. Third it is a key region of deepwater formation. This project thus includes a focused effort to improve representation and diagnosis of the dynamics of subpolar/Arctic exchanges and their connection to variable Arctic Ocean water masses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.