Data Assimilation in a Strongly Nonlinear Ocean Model

本文将利用正压和斜压准地转模型解的动力学系统分析来研究控制黑潮许多路径的物理特性。动力系统工具将用于确定黑潮在日本海岸外路径的模型模拟的定性性质。斜压准匀转区域模式及其伴随模式将与以往模式研究的现有解进行比较。预计正压系统和斜压系统的分岔图相似，但解将表现出明显的斜压效应。斜压准匀转模式的伴随将用于研究该模式对不同类型扰动的敏感性，并确定观测同化对每种不同大小曲流情况下模式预测的影响。数据同化研究也将有助于确定哪些观测预测从一种状态到另一种状态的转变。此外，研究的这一部分将有助于区分不同的物理模型在表示系统的自然变异性方面的不足之处。这项研究将有助于更好地理解日本的黑潮系统，产生黑潮双峰的不同物理机制，并有可能为捕获系统行为的关键观察集提供指导。

Proposal Number: 0137169PI: R. Miller, OSUThe physics governing the many paths of the Kuroshio will be investigated using dynamical systems analysis of barotropic and baroclinic quasigeostrophic model solutions. The dynamical systems tools will be used to determine the qualitative nature of model simulations of the Kuroshio's path off the coast of Japan. A baroclinic quasigeostrophic regional model and its adjoint will be used comparatively with existing solutions from previous model studies. It is expected that the bifurcation diagram will be similar between the barotropic and baroclinic systems but that the solutions will exhibit significant baroclinic effects. The adjoint of the baroclinic quasigeostrophic model will be used to investigate the sensitivity of the model to different types of perturbations and to determine the influence of assimilation of observations on the model predictions in each different small and large meander case. The data assimilation study will also help determine which observations predict the transition from one state to another. In addition, this portion of the study will help discriminate between the adequacies of different physics in different models for representing the natural variability of the system. This study will lead to a better understanding of the Kuroshio system off Japan, the different physical mechanisms that generate bimodality of the Kuroshio, and it has the potential to yield guidance towards the critical set of observations that capture the behavior of the system.