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首页> 外文学位 >Application of a hybrid 3D-var data assimilation system in the Monterey Bay to study regional dynamics of the California Current System.
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Application of a hybrid 3D-var data assimilation system in the Monterey Bay to study regional dynamics of the California Current System.

机译：蒙特雷湾混合3D-var数据同化系统在研究加利福尼亚洋流系统区域动态中的应用。

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摘要

A data assimilation system combining 3-dimensional variational scheme and Navy Coastal Ocean Model was applied to the Monterey Bay area to assimilate temperature and salinity glider data collected in August 2003. The hybrid background error covariance model in the present 3-dimensional variational system incorporates both the static and the flow-dependent background error covariance. To explore the impact of high temporal resolution on the overall skill of the assimilation system, the intended data assimilation interval was set to 1 hour in the present study. A Floating Temporal Window approach is designed to keep the computational efficiency of the scheme and to retain the flow-dependent. Both twin data experiments with "synthetic" data and real data experiments were performed in the present study.;The performance of the traditional 3-dimensional variational scheme and the hybrid scheme in twin data experiments were evaluated with respect to the "true state." The hybrid scheme reduces both temperature and salinity errors during the twin data experiment, especially during the transition period from wind relaxation to upwelling events and vice versa.;In real data experiments, the model performance is validated against independent mooring observations. In the first real data experiment, the model free run, data assimilation run with traditional scheme, and data assimilation run with hybrid scheme were compared. The assimilation skill was tested by calculating the normalized distance between the assimilation results and observations at the mooring locations. The performance of the hybrid scheme generally exceeded the performance of the traditional scheme. Although there was no velocity data assimilation in the experiments, the change of temperature and salinity fields originated from glider data assimilation had a positive impact on the velocity fields according to mooring velocity records.;The second real data experiment compared the hybrid schemes with the full ensemble and the Floating Temporal Window ensemble. Results showed that the Floating Temporal Window scheme provided lower discrepancy between the values of temperature, salinity and velocity predicted by the model and observed at the moorings. The improvement became more clearly visible during the upwelling and relaxations events associated with intermittent wind forcing.;The results from the Navy Coastal Ocean Model free run and the data assimilation run with the hybrid scheme were compared with historical data. Comparisons have shown that the Navy Coastal Ocean Model combining with the hybrid 3-dimensional variational assimilation system was capable of reproducing major dynamical features, including onshore-offshore translation of the Monterey Bay Eddy during upwelling and relaxation events, coastal upwelling and respective upwelling filaments, the appearance of the California Undercurrent, and the interaction between the California Undercurrent and California Current.
机译：在蒙特里湾地区应用了将3维变分方案和海军海岸海洋模型相结合的数据同化系统，以同化2003年8月收集的温度和盐度滑翔机数据。在本3维变分系统中，混合背景误差协方差模型将两者结合起来静态和流量相关的背景误差协方差。为了探索高时间分辨率对同化系统整体技能的影响，在本研究中将预期的数据同化间隔设置为1小时。设计浮动时空窗口方法以保持该方案的计算效率并保持与流量有关。在本研究中，都执行了具有“合成”数据的双数据实验和真实数据实验。；针对“真实状态”评估了传统3D变分方案和混合方案在双数据实验中的性能。在双数据实验期间，特别是在从风弛豫到上升流事件的过渡期间，反之亦然，混合方案降低了温度和盐度误差。在实际数据实验中，针对独立的系泊观测值验证了模型性能。在第一个真实数据实验中，比较了模型自由运行，使用传统方案的数据同化和使用混合方案的数据同化。通过计算同化结果与系泊位置观测值之间的标准化距离来测试同化技能。混合方案的性能通常超过传统方案的性能。尽管实验中没有速度数据同化，但根据系泊速度记录，源自滑翔机数据同化的温度和盐度场的变化对速度场产生了积极影响。合奏和Floating Temporal Window合奏。结果表明，浮动时间窗方案在模型预测并在系泊处观测到的温度，盐度和速度值之间的差异较小。在间歇性强迫风引起的上涌和松弛事件中，这种改进变得更加明显。;将海军沿海海洋模型自由运行的结果以及混合方案的数据同化结果与历史数据进行了比较。比较结果显示，海军沿海海洋模型与混合的3维变分同化系统相结合，能够再现主要的动力学特征，包括上升和松弛事件期间蒙特雷湾涡流的岸上-近海平移，沿海上升流以及各个上升流细丝，加利福尼亚暗流的出现，以及加利福尼亚暗流和加利福尼亚洋流之间的相互作用。

著录项

  • 作者

    Pan, Chudong.;

  • 作者单位

    The University of Southern Mississippi.;

  • 授予单位 The University of Southern Mississippi.;
  • 学科 Physical Oceanography.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 155 p.
  • 总页数 155
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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