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

利用1993 ~ 1997年5年的高分辨率1 1/2层原始方程模式同化绝对海面动力高度资料，研究了日本以南黑潮路径变率的短期预报能力。初始化方案采用变分法，该方法包含模式的非线性动力学作为弱约束，适用于西部边界流区的初始化.分析场的时间序列很好地反映了研究期间黑潮路径的变化.与观测值的均方根差福尔斯落在恩州外当前轴纬度位置的0.3°以内。nada，而观测到的均方根变率为0.5°。然后，以所得场为初始条件，进行了116个黑潮路径变化的90天预报试验，以评估我们同化系统的统计特性。我们f的准确性 ...更多信息 日本南部的持续流场比持续流场高得多，并且在初始化后成功地再现了黑潮向恩州那达外海大振幅路径的典型演变过程。特别是东进速度和水平尺度的曲流是非常相似的观察。这些结果和分析场的均方根变率的比较，使我们能够推断，大约60天的预测的黑潮路径变化的日本南部是可能的。其次，为了估计总热量输送的黑潮，我们已经建立了一个4D-VAR海洋数据同化系统，使用海洋环流模式和伴随方法。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充分估计黑潮热量输送的数据同化系统。少

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