斜压罗斯贝变形半径优化的误差相关尺度及其对最优插值效果的改进

The correlation length-scale optimized by baroclinic Rossby radius of deformation and its improvement to optimum interpolation

利用最优插值方法进行三维温盐场重构时,如何正确估算背景场误差协方差至关重要。针对背景场误差协方差主要取决于误差相关尺度的问题,本文提出了用中国东部海域及其附近海域的最新的高分辨率气候态数据进行斜压罗斯贝变形半径优化其误差相关尺度计算的研究方案和技术途径;对比分析了均一化相关尺度方案和法国ISAS系统尺度方案,讨论了变形半径对最优插值的影响。结果表明:均一化相关尺度方案的均方根误差小于ISAS方案,但温度场过于平滑,难以刻画一些重要的物理现象;相比而言,本文提出的基于变形半径的相关尺度方案在取2倍变形半径时,不仅均方根误差在各水平层较小,且温度场能够更好地刻画四国海盆海域涡旋及黑潮影响的温度场三维结构。由于实际海洋中各层物理过程的尺度存在差异,实际应用时各层的最优尺度设置也应有所不同。

Three-dimensional reconstruction of temperature and salinity based on Optimal interpolation requires cor-rect estimation of the background error covariance and the error correlation scale is determined by baroclinic Rossby radius of deformation.According this issue,they proposed a research scheme of optimizing the correlation length-scale by baroclinic Rossby radius of deformation using the newest high resolution regional climatological data.In this paper,they compared the different results calculated by homogenization correlation scale scheme,the French ISAS scale scheme and the radius of deformation scheme.The results showed that：the RMSE of homogenization correlation scales scheme was much smaller than that of ISAS scheme,but pattern of temperature was too smooth and appears unreasonable extremes,so it could not describe some of the important physical phenomena;when the error correlation length was taken as 2 times the radius of deformation,the RMSE at every level was relatively smaller;in addition,the temperature calculated by the new scales scheme determined by the radius of deformation could better describe the three-dimensional structure of temperature affected by both Kuroshio and vortex field in Shikoku basin.As the actual physical processes in the ocean were different,the settings of optimal scales scheme was different in different layers.