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首页> 外文学位 >Estimation of mid-latitude Rossby waves using a simple ocean model and Kalman filtering with TOPEX/POSEIDON altimeter data.
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Estimation of mid-latitude Rossby waves using a simple ocean model and Kalman filtering with TOPEX/POSEIDON altimeter data.

机译：使用简单的海洋模型和带有TOPEX / POSEIDON高度计数据的卡尔曼滤波估算中纬度Rossby波。

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Long baroclinic Rossby waves are a mechanism by which mid-latitude oceans adjust to low frequency wind forcing. Observation of such large-scale planetary waves with Earth based observation systems has always been difficult. In this work, we describe a technique for inverse modeling of long baroclinic Rossby waves based on simulated annealing and Kalman filtering of TOPEX satellite altimeter data. The mid-latitude dynamics of the model are governed by the low-frequency forced quasi-geostrophic vorticity equation on a {dollar}beta{dollar}-plane, which limits sea surface height anomaly (SSHA) changes to those caused by radiation of long (nondispersive) Rossby waves and Ekman pumping. An additional local seasonal heating and cooling is introduced to account for the annual steric signal. The SSHA is the dependent variable, while free parameters predetermined by simulated annealing include the reduced gravity, the westward Rossby wave speed, and phase and amplitude of the local seasonal heating. A Kalman filter, based on the model dynamics forced with '93-'95 wind stress anomalies is used with TOPEX SSHA data and the annealed parameter estimates. The filter state vector is constructed along a line of latitude in each basin and is comprised of a mean phase speed from the annealing and the TOPEX SSHA observations at one degree resolution. Regions of free wave and Ekman pumping activity were identified by correlating individual terms to the time rate of change of the filtered SSHA after removing the estimate of the local heat flux. Free wave propagation was found to exist throughout most of the global oceans. Filtered phase speeds at high latitudes were faster than those predicted by linear Rossby wave theory as found in earlier subjective studies. To identify frequency components in the filtered TOPEX data, a multi-channel singular spectrum analysis (MSSA) techniques was used. Semiannual, annual, and interannual components were extracted. Correlations of the Rossby and Ekman terms with the reconstructed signals showed that semiannual and annual frequencies were dominated by wind forcing, while interannual waves may be forced by other mechanisms such as Kelvin wave reflection.
机译：长斜压罗斯比波是中纬度海洋适应低频风强迫的一种机制。用基于地球的观测系统观测如此大规模的行星波一直很困难。在这项工作中，我们描述了一种基于TOPEX卫星高度计数据的模拟退火和卡尔曼滤波的长斜压Rossby波逆建模技术。该模型的中纬度动力学受{dolal} beta {dollar}平面上的低频强迫拟地转涡度方程控制，该方程将海表高度异常（SSHA）的变化限制为由长距离辐射引起的变化（非分散）罗斯比波和埃克曼泵浦。引入了额外的本地季节性供暖和制冷以解决年度空间信号。 SSHA是因变量，而通过模拟退火预先确定的自由参数包括减小的重力，向西的Rossby波速以及局部季节性加热的相位和幅度。基于TOPEX SSHA数据和退火参数估计值，基于基于'93 -'95风应力异常迫使的模型动力学的卡尔曼滤波器。过滤器状态向量是沿着每个盆地中的纬度线构造的，由退火和TOPEX SSHA观测值在一个度分辨率下的平均相速度组成。在去除局部热通量估计值之后，通过将各个项与过滤后的SSHA的时间变化率相关联，可以确定自由波和Ekman抽水活动的区域。发现在全球大多数海洋中都存在自由波传播。高纬度的滤波相速度比早期主观研究中线性罗斯比波理论所预测的要快。为了识别滤波后的TOPEX数据中的频率分量，使用了多通道奇异频谱分析（MSSA）技术。提取半年度，年度和年际成分。 Rossby和Ekman项与重建信号的相关性表明，半年度和年度频率主要受强迫作用，而年际波可能受开尔文波反射等其他机制强迫。

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