权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Analysis of heat transport driven by the Kuroshio and short-range forecast of the Kuroshio variabilities using data assimilation methods

利用数据同化方法分析黑潮驱动的热传输和黑潮变化的短期预测

基本信息

批准号：
11440140
负责人：
AWAJI Toshiyuki
金额：
$ 3.9万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Capability for short-range forecasting of the Kuroshio path variabilities south of Japan is studied by assimilating the absolute sea surface dynamic height data into a high-resolution 1 1/2-layer primitive equation model for 5 years from 1993 to 1997. The initialisation scheme used is the variational method, which contains the nonlinear dynamics of the model as a weak constraint and is suitable for initialization in the western boundary current regions.The time series of the analysis field well represents the-Kuroshio path variations during the study period For example, the rms differences from the observations falls within 0.3°for the location in latitude of the current axis off Enshu-nada while their observed rms variability is 0.5°By using the resulting fields as the initial conditions, one hundred and sixteen cases of 90-day forecast experiments for the Kuroshio path variations are then performed to assess the statistical properties of our assimilation system. The accuracy of our f … More orecasted field south of Japan is much higher than that of persistence experiments and the typical evolution of the Kuroshio into a large-amplitude path off Enshu-nada is successfully reproduced after the initialization. In particular, the eastward progression speed and the horizontal scale of the meander are quite similar to those observed. These results and the comparison with the rms variability of the analysis field enable us to infer that roughly 60-day forecasts of the Kuroshio path variabilities south of Japan are possible.Next, in order to estimate the total heat transport by the Kuroshio, we have constructed a 4D-VAR ocean data assimilation system using an ocean general circulation model and the adjoint method. The result demonstrates the validity of this reanalysis data. For example, the Kuroshio path is corrected to be more realistic and the surface heat flux reanalysis data in the Pacific Ocean represents most of the familiar gross features of past studies. These improvements allow us to estimate the Kuroshio heat transport adequately by our data assimilation system. Less

通过将1993年至1997年5年的绝对海面动力高度数据同化到高分辨率1 1/2层原方程模型中，研究日本南部黑潮路径变率的短期预报能力。采用的初始化方案是变分法，该方法将模型的非线性动力学作为弱约束，适合于西部边界流区的初始化。分析的时间序列场很好地代表了研究期间的黑潮路径变化。例如，对于远州滩当前轴的纬度位置，观测值与观测值的均方根差异在0.3°以内，而观测到的均方根变化为0.5°。以所得场作为初始条件，然后对黑潮路径变化进行了116个90天的预测实验，以评估统计结果我们的同化系统的特性。我们在日本南部的预测场的精度远高于持久性实验的精度，并且在初始化后成功再现了黑潮到远州滩附近大振幅路径的典型演化。特别是曲流的东进速度和水平尺度与观测结果非常相似。这些结果以及与分析场均方根变异性的比较使我们能够推断，对日本南部黑潮路径变化的大约 60 天的预测是可能的。接下来，为了估计黑潮的总热量传输，我们使用海洋环流模型和伴随方法构建了 4D-VAR 海洋数据同化系统。结果证明了该再分析数据的有效性。例如，黑潮路径被修正得更加真实，太平洋表面热通量再分析数据代表了过去研究中大多数熟悉的总体特征。这些改进使我们能够通过数据同化系统充分估计黑潮热传输。较少的