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中尺度涡在大洋环流中有着重要的作用. 为检验高度计资料同化应用于中尺度涡模拟的效果, 提高环流模式对中尺度涡模拟的精度, 使用三维变分的OVALS同化系统结合POM模式进行了中尺度涡同化模拟实验. 该系统将卫星高度计资料同化反演成为温盐伪观测数据, 然后再次进行常规温盐同化, 得到温盐分析场. 根据中尺度涡现象的物理特性, 经过对比检验, 对系统中的同化参数作了合理设置. 使用T/P和ERS1/2的10 a卫星高度计的海表高度异常资料, 分别用同化与非同化两种方案对西北太平洋的中尺度涡进行对比模拟实验. 将实验结果与观测数据的比较表明, 加入高度计资料同化的模拟结果远远好于未使用同化的模拟结果. 说明高度计反演温盐场的同化方法用于对于模拟中尺度涡现象是非常有效的. 相似文献
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集合最优插值中的样本选取 总被引：1，自引：0，他引：1
背景误差协方差控制了分析向观测调整的幅度以及调整的结构,所以其对同化分析的质量起着至关重要的作用。对于集合同化方法而言,样本决定了背景误差协方差的分布。基于HYCOM海洋数值模式结果,针对集合最优插值方法,探讨了静态样本的选取和更新对背景误差协方差结构分布的影响,研究结果表明：由变量的原始状态数据估计的静态样本会夸大样本相关性,由扣除季节变化得到的距平数据统计出的静态样本能比较合理地反映背景误差协方差的结构;在季风控制区,具有季节变化的样本比静态样本更能适应背景误差协方差随流形分布的特征。同时一系列的同化试验也被实施来进一步调查不同样本对同化分析的影响。 相似文献
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Impacts of XBT, TAO, Altimetry and ARGO Observations on the Tropical Pacific Ocean Data Assimilation 总被引：2，自引：0，他引：2
This study aims at assessing the relative impacts of four major components of the tropical Pacific Ocean observing system on assimilation of temperature and salinity fields. Observations were collected over a period between January 2001 through June 2003 including temperature data from the expendable bathythermographs （XBT）, thermistor data from the Tropical Ocean Global Atmosphere Tropical Atmosphere-Ocean （TOGA-TAO） mooring array, sea level anomalies from the Topex/Poseidon and Jason-1 altimetry （T/P-J）, and temperature and salinity profiles from the Array for Real-time Geostrophic Oceanography （ARGO） floats. An efficient three-dimensional variational analysis-based method was introduced to assimilate the above data into the tropical-Pacific circulation model. To evaluate the impact of the individual component of the observing system, four observation system experiments were carried out. The experiment that assimilated all four components of the observing system was taken as the reference. The other three experiments were implemented by withholding one of the four components. Results show that the spatial distribution of the data influences its relative contribution. XBT observations produce the most distinguished effects on temperature analyses in the off-equatorial region due to the large amount of measurements and high quality. Similarly, the impact of TAO is dominant in the equatorial region due to the focus of the spatial distribution. The Topex/Poseidon-Jason-1 can be highly complementary where the XBT and TAO observations are sparse. The contribution of XBT or TAO on the assimilated salinity is made by the model dynamics because no salinity observations from them are assimilated. Therefore, T/P-J, as a main source for providing salinity data, has been shown to have greater impacts than either XBT or TAO on the salinity analysis. Although ARGO includes the subsurface observations, the relatively smaller number of observation makes it have the smallest contribution to the assimilation syst 相似文献
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一个三维变分海洋资料同化系统的设计和初步应用 总被引：3，自引：1，他引：3
介绍了新完成的一个基于三维变分方法的通用海洋资料同化系统OVALS(Ocean Variational Analysis System)的设计方案和在热带太平洋海洋资料同化中的初步应用. OVALS可以同化常规的现场海洋温盐观测资料和卫星高度计资料, 其中在海面高度资料同化中引入了一个新的基于三维变分的同化方案, 该方案考虑了背景场误差的垂直相关性和非线性的温-盐关系. 非线性的温-盐关系是通过将三维变分方法中的线性平衡约束方案推广到非线性的情况来实现的, 从而通过同化高度计资料来直接调整模式的温度和盐度场. 另外, OVALS还可以同化近年来投入运行的国际ARGO漂流浮标的温、盐廓线资料以及其他海温和盐度资料, 如船报海温资料和一些浮标阵列资料等. 利用OVALS和大洋环流模式在热带太平洋进行了21 a的同化试验. 试验结果表明, 同化系统通过对各种海洋资料的同化, 可以有效改进对海洋温度和盐度的估计, 其在420 m深度以浅的上层海洋的月平均温、盐度估计误差分别为0.63℃和0.34 psu. 相似文献
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A ＂Dressed＂ Ensemble Kalman Filter Using the Hybrid Coordinate Ocean Model in the Pacific 总被引：1，自引：0，他引：1
The computational cost required by the Ensemble Kalman Filter (EnKF) is much larger than that
of some simpler assimilation schemes, such as Optimal Interpolation (OI) or three-dimension variational
assimilation (3DVAR). Ensemble optimal interpolation (EnOI), a crudely simplified implementation of EnKF,
is sometimes used as a substitute in some oceanic applications and requires much less computational time
than EnKF. In this paper, to compromise between computational cost and dynamic covariance, we use the
idea of ``dressing' a small size dynamical ensemble with a larger number of static ensembles in order
to form an approximate dynamic covariance. The term ``dressing' means that a dynamical ensemble seed
from model runs is perturbed by adding the anomalies of some static ensembles. This dressing EnKF (DrEnKF
for short) scheme is tested in assimilation of real altimetry data in the Pacific using the HYbrid
Coordinate Ocean Model (HYCOM) over a four-year period. Ten dynamical ensemble seeds are each dressed by
10 static ensemble members selected from a 100-member static ensemble. Results are compared to two EnKF
assimilation runs that use 10 and 100 dynamical ensemble members. Both temperature and salinity fields
from the DrEnKF and the EnKF are compared to observations from Argo floats and an OI SST dataset. The
results show that the DrEnKF and the 100-member EnKF yield similar root mean square errors (RMSE) at
every model level. Error covariance matrices from the DrEnKF and the 100-member EnKF are also compared
and show good agreement. 相似文献
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三维变分资料同化中的非线性平衡约束 总被引：1，自引：2，他引：1
在三维变分资料同化的许多应用中, 平衡约束都是通过背景误差协方差矩阵B来考虑的: 首先, 要定义模式变量非平衡部分的背景误差协方差矩阵B(u)(一个块对角矩阵); 其次, 要定义一个把非平衡部分变换到模式变量的平衡算子, 再用B =KB(u)K T来构造B . 这种形式只适用于那些线性或线性化的平衡约束. 许多实际应用中需要考虑非线性平衡约束, 比如海洋资料同化中的温盐关系. 我们在线性形式的基础上, 导出了几种可以推广到非线性的形式, 提出了在三维变分同化中考虑非线性平衡约束的方案. 利用提出的方案, 进行了从海面动力高度来估计温、盐的资料同化数值试验. 结果表明, 考虑非线性平衡约束的方案比不考虑非线性平衡约束的方案对结果有很大改善. 相似文献
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