Anomaly transform methods based on total energy and ocean heat content norms for generating ocean dynamic disturbances for ensemble climate forecasts
Anomaly transform methods based on total energy and ocean heat content norms for generating ocean dynamic disturbances for ensemble climate forecasts
复制标题
基于总能量和海洋热含量范数的异常变换方法，用于产生集合气候预报的海洋动力扰动
DOI：
10.1007/s00382-015-2567-4
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发表时间：
2017
期刊：
影响因子：
4.6
通讯作者：
A. Hense
中科院分区：
文献类型：
--
作者：
V. Romanova;A. Hense
在我们的研究中，我们使用异常变换，系综变换方法的一个特殊情况下，其中一组选定的初始海洋异常的空间，时间和变量的定义和正交化。由此产生的正交扰动模式的设计，使他们拿起典型的平衡异常结构在空间和时间和变量之间。用于建立本征问题的度量被视为加权总能量，其纬向，纬向动能和可用势能项具有相等的贡献，或加权海洋热含量，其中扰动仅适用于初始温度场。定义初始异常的参考状态的选择是这样的，无论是在季节时间尺度和或年际时间尺度上的扰动构造。这些项目先验只有海洋物理过程的缓慢模式，这样的扰动增长主要在西部边界电流，在南极绕极电流和厄尔尼诺南方涛动区域。一组额外的初始条件的设计，以适应在最小二乘意义上的数据从全球海洋再分析。应用AT产生的扰动集的海洋初始条件的观测MPIOM-ESM耦合模式T63 L47/GR 15分辨率，4个集合和一个后投实验进行。加权总能量范数用于监控增长最快的误差模式的幅度和速率。结果表明，不稳定性或误差增长对所选度量的较小依赖性，但由于扰动模式的标度振幅的大小而发生相当大的变化。在类似的大气应用相反，我们发现一个能量转换从动能到可用的势能，这表明在海洋中产生的不确定性的不同来源比在大气中主要与密度场的变化。
In our study we use the anomaly transform, a special case of ensemble transform method, in which a selected set of initial oceanic anomalies in space, time and variables are defined and orthogonalized. The resulting orthogonal perturbation patterns are designed such that they pick up typical balanced anomaly structures in space and time and between variables. The metric used to set up the eigen problem is taken either as the weighted total energy with its zonal, meridional kinetic and available potential energy terms having equal contributions, or the weighted ocean heat content in which a disturbance is applied only to the initial temperature fields. The choices of a reference state for defining the initial anomalies are such that either perturbations on seasonal timescales and or on interannual timescales are constructed. These project a-priori only the slow modes of the ocean physical processes, such that the disturbances grow mainly in the Western Boundary Currents, in the Antarctic Circumpolar Current and the El Nino Southern Oscillation regions. An additional set of initial conditions is designed to fit in a least square sense data from global ocean reanalysis. Applying the AT produced sets of disturbances to oceanic initial conditions initialized by observations of the MPIOM-ESM coupled model on T63L47/GR15 resolution, four ensemble and one hind-cast experiments were performed. The weighted total energy norm is used to monitor the amplitudes and rates of the fastest growing error modes. The results showed minor dependence of the instabilities or error growth on the selected metric but considerable change due to the magnitude of the scaling amplitudes of the perturbation patterns. In contrast to similar atmospheric applications, we find an energy conversion from kinetic to available potential energy, which suggests a different source of uncertainty generation in the ocean than in the atmosphere mainly associated with changes in the density field.
影响因子：
4.6
作者：
Goddard, L.;Kumar, A.;Delworth, T.
通讯作者：
Delworth, T.
影响因子：
5.1
作者：
J. Baehr;R. Piontek
通讯作者：
J. Baehr;R. Piontek
关于育种向量的正交化
影响因子：
2.9
作者：
Keller;Kornblueh L;Rhodin A.
通讯作者：
Rhodin A.