New CNES‐CLS09 global mean dynamic topography computed from the combination of GRACE data, altimetry, and in situ measurements
New CNES‐CLS09 global mean dynamic topography computed from the combination of GRACE data, altimetry, and in situ measurements
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DOI：
10.1029/2010jc006505
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发表时间：
2011-07
影响因子：
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通讯作者：
M. Rio;S. Guinehut;G. Larnicol
中科院分区：
文献类型：
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作者：
M. Rio;S. Guinehut;G. Larnicol
[1]对海洋平均动态地形(MDT)的准确了解是最佳利用测高数据的必要条件，包括将其同化到业务海洋预报系统中。计算了1993-1999年期间新的全球1/4°分辨率MDT，与以前的RIO05 MDT场相比，改进了数据和方法。首先，从CLS01高程平均海面和最近4.5年GRACE(重力恢复和气候实验)数据计算的大地水准面模型得到了大尺度的MDT。然后，将海平面高程异常和现场测量结合起来，计算MDT和相应平均海流的综合估计值。虽然RIO05 MDT是基于10年的现场动态高度和漂流浮标速度，但新的现场受益于1993年至2008年扩大的现场测量数据集，并包括Argo阵列的所有水文剖面。此外，对现场数据的处理进行了更新。发展了一种新的Ekman模型，用于从漂移浮标测量数据中提取地转速度分量。还重新讨论了水文测量的处理问题。与以前的RIO05解相比，新的全球MDT解决了西部边界流中更强的梯度，一些地方的平均速度增加了一倍。此外，与其他几个最近的MDT估计相比，我们发现新的CNES-CLS09 MDT与独立的现场观测更符合。
[1] An accurate knowledge of the ocean mean dynamic topography (MDT) is mandatory for the optimal use of altimetric data, including their assimilation into operational ocean forecasting systems. A new global 1/4° resolution MDT was computed for the 1993–1999 time period with improved data and methodology compared to the previous RIO05 MDT field. First, a large-scale MDT is obtained from the CLS01 altimetric Mean Sea Surface and a recent geoid model computed from 4.5 years of GRACE (Gravity Recovery and Climate Experiment) data. Altimetric sea level anomalies and in situ measurements are then combined to compute synthetic estimates of the MDT and the corresponding mean currents. While the RIO05 MDT was based on 10 years of in situ dynamic heights and drifting buoy velocities, the new field benefits from an enlarged data set of in situ measurements ranging from 1993 to 2008 and includes all hydrological profiles from the Argo array. Moreover, the processing of the in situ data has been updated. A new Ekman model was developed to extract the geostrophic velocity component from the drifting buoy measurements. The handling of hydrologic measurements has also been revisited. Compared to the previous RIO05 solution, the new global MDT resolves much stronger gradients in western boundary currents, with mean velocities being doubled in some places. Moreover, in comparison to several other recent MDT estimates, we find that the new CNES-CLS09 MDT is in better agreement with independent in situ observations.