Variability of the California Current System Derived from 4D-Var Circulation Estimates

由 4D-Var 环流估计得出的加州海流系统的变异性

• 批准号: 1061434
• 负责人: Andrew Moore
• 金额: $ 84.04万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1061434&HistoricalAwards=false
• 关键词: Variability; California; Current; System; Derived

A comprehensive analysis of the U.S. west coast ocean circulation and California Current System (CCS) will be performed using the Regional Ocean Modeling System (ROMS) and 4-Dimensional Variational (4D-Var) data assimilation. Ocean observations from the period 1981-2011 will be assimilated into ROMS, in conjunction with the best available estimates of ocean surface forcing and open boundary conditions. The goals of this research project are: (1) To perform retrospective analyses of the ocean circulation during the last 3 decades; (2) Use the analyses to document and understand changes in spring-summer stratification and how these changes, along with variations in wind-stress and wind-stress curl, influence upwelling intensity and upwelling source water depth; (3) Identify the dominant space-time modes of circulation variability on intraseasonal-to-interannual and decadal timescales and how these modes are related to climate modes such as the Pacific decadal Oscillation and North Pacific Gyre Oscillation; (4) Quantify the impact on the analyses of the in situ and satellite observing networks; (5) Make the circulation analyses available via a data server to the community at large for scientific and marine resource management applications.Intellectual meritThis research will yield the first analyses of the California Current System circulation generated by a regional ocean model forced by the best available ocean surface fluxes from regional atmospheric models. Also, this assimilative ocean model is unique in that it provides formal estimates of the expected error in the analyses, and provides a quantitative assessment of the impact of each individual observation on any aspect of the resulting circulation estimates. Analysis error estimates are critically important for establishing confidence in the analyses, and observation impact and observation sensitivity studies can be used in the future to design optimal observing arrays. A by-product of the proposed analyses are fields of surface forcing and open boundary condition corrections that provide information about potential errors in these fields and errors in the model. The investigators are a uniquely qualified and experienced team of ocean modelers, all with considerable experience in both modeling the CCS and 4D-Var data assimilation, and the lead investigator is one of the lead developers of the ROMS 4D-Var system.Broader impactsThe proposed retrospective ocean analyses are significant for a number of reasons: (i) They can be used to quantify variability on weekly to decadal timescales, and trends in the dominant circulation features, particularly in subsurface regions that are not well observed; (ii) They provide complete realizations of the circulation at high temporal resolution on the full grid of the model that are largely free of the sampling and aliasing issues that often plague observations; (iii) They can be used to test hypotheses about ocean dynamics, climate variability, and climate change. The resulting analyses will form a valuable community resource in the form of a data archive that can be used for numerous applications, including: process studies of the CCS; input for driving offline ecosystem and individual based models; a source of open boundary conditions for higher resolution models nested within the native ROMS CCS grid; and initial conditions for the development of ocean hindcasting/forecasting systems, to name but a few. This project will also provide training for a graduate student and post-doctoral researchers in advanced 4D-Var data assimilation methods, since it is important that we continue to train the next generation of ocean data assimilators. The proposed research will also use the adjoint of 4D-Var which is an original and transformative aspect of this work. This project will also complement the NSF Ocean Observatories Initiative, and will support synthesis activities, development of user products, and array assessment within the U.S. Integrated Ocean Observing Systems along the U.S. west coast.

将使用区域海洋建模系统（ROMS）和4维变分（4D-VAR）数据同化对美国西海岸海洋流通和加利福尼亚当前系统（CCS）进行全面分析。 1981 - 2011年期间的海洋观测将与海面强迫和开放边界条件的最佳可用估计结合在一起。该研究项目的目标是：（1）在过去30年中对海洋循环进行回顾性分析； （2）使用分析记录和理解春季夏季分层的变化，以及这些变化以及风压力和风压力卷曲的变化，影响上升强度和上升的源水深； （3）确定季节到年龄段和十年时间尺度上循环变异性的主要时空模式，以及这些模式与气候模式（例如太平洋十分振荡和北太平洋Gyre振荡）如何相关； （4）量化对原位和卫星观察网络分析的影响； （5）通过数据服务器向整个社区提供循环分析，以用于科学和海洋资源管理应用程序。智能优点这项研究将产生对加利福尼亚当前系统循环的首次分析，该系统由区域大气模型的最佳可用海面磁通剂强迫产生的区域海洋模型产生。同样，这种同化海洋模型的独特之处在于，它提供了分析中预期错误的正式估计，并对每个单独观察结果对所得循环估计的任何方面的影响进行定量评估。分析误差估计对于在分析中建立信心至关重要，将来可以使用观察影响和观察灵敏度研究来设计最佳观察阵列。所提出的分析的副产品是表面强迫和开放边界条件校正的字段，可提供有关这些领域中潜在错误的信息以及模型中的误差。研究人员是一支具有独特且经验丰富的海洋建模者团队，在建模CC和4D-VAR数据同化方面都有丰富的经验，主要研究者是ROM 4D-VAR系统的主要开发商之一。拟议的回顾性分析可以在范围内进行多种变化：（i）的趋势：（i）有很大的变化：（i）的趋势：（i）的趋势是：主要的循环特征，尤其是在没有很好地观察到的地下区域； （ii）他们在模型的完整网格上完全实现了循环的完整实现，这些分辨率在很大程度上没有遇到通常困扰观察结果的抽样和混叠问题； （iii）它们可用于测试有关海洋动力学，气候变化和气候变化的假设。由此产生的分析将以数据存档的形式形式形成宝贵的社区资源，该资源可用于众多应用程序，包括：CCS的过程研究；用于驱动离线生态系统和基于个体模型的输入；嵌套在天然ROM CCS网格中的高分辨率模型的开放边界条件的来源；以及开发海洋后广播/预测系统的初始条件，仅举几例。该项目还将为高级4D-VAR数据同化方法的研究生和博士后研究人员提供培训，因为我们继续培训下一代海洋数据同化器很重要。拟议的研究还将使用4D-VAR的伴随，这是这项工作的原始和变革性的方面。该项目还将补充NSF海洋天文台倡议，并将支持美国西海岸沿美国综合海洋观测系统的合成活动，用户产品的开发和阵列评估。