Refining the Resolution of DUACS Along-Track Level-3 Sea Level Altimetry Products
Refining the Resolution of DUACS Along-Track Level-3 Sea Level Altimetry Products
复制标题
提高 DUACS 沿轨 3 级海平面测高产品的分辨率
作者：
M. Pujol;S. Dupuy;O. Vergara;A. Sánchez;Y. Faugère;P. Prandi;Mei;Q. Dagneaux;Marine Lievin;E. Cadier;G. Dibarboure;N. Picot
本文介绍了在法国国家空间研究中心（CNES）支持下开发的区域高分辨率三级（L3）高度计数据统一和高度计组合系统（DUACS）的演示。该产品从全速率（20 Hz至40 Hz）2级（L2）高度计测量值中推导出来，以北大西洋上空每1 km一个样本的空间分辨率提供海平面异常（SLA）和其他基本物理变量。这使我们能够分辨波长从~35公里到~55公里，这取决于所考虑的高度计。这是由于最近在雷达高度表处理合成孔径雷达和低分辨率模式测量方面取得的进展，以及对DUACS处理链不同阶段的改进。首先，新的自适应和低分辨率距离徙动校正（LR-RMC）处理技术被认为是杰森和哨兵-3（S3 A）分别。它们大大减少了短波长的误差，自适应处理也减少了海岸附近可能的土地污染。接下来，为这次生产选择了最新的地球物理和环境校正。这包括旨在减少LRM测量的测量噪声的特定校正，从而增强短波长下的可观测性。与1赫兹产品相比，演示高分辨率产品达到的可观测波长减少了三分之一，在东北大西洋区域减少了一半。考虑到所处理的高度计的不同观测能力，从全速率测量中最佳地滤除了残余噪声。采用了具体的数据恢复战略，大大优化了沿海和公海地区的数据可用性。因此，该演示L3产品比传统的1 Hz产品更好地分辨，特别是在海岸附近，在那里它被定义为高达~5 km，而1 Hz版本为~10 km。多任务交叉校准处理也通过改进的长波长误差（LWE）校正进行了优化，从而提高了航迹之间的一致性，交叉时SLA方差降低了9-15%。新的L3产品提高了与验潮仪测量的整体一致性，与S3 A和Jason-3（J3）测量的1 Hz产品相比，SLA差异方差分别减少了5%和17%。该产品主要用于区域应用，可通过数据同化为改进高分辨率数值模式输出作出重大贡献。它还为更好地了解区域海面动态开辟了新的视角，改进了沿海海流的表示，并改进了揭示不平衡信号的频谱内容。
This paper describes the demonstration of a regional high-resolution level-3 (L3) altimeter data unification and altimeter combination system (DUACS) developed with support from the French space agency (CNES). Deduced from full-rate (20 Hz to 40 Hz) level-2 (L2) altimeter measurements, this product provides sea level anomalies (SLA) and other essential physical variables at a spatial resolution of one sample every ~1 km over the North Atlantic Ocean. This allows us to resolve wavelengths from ~35 km to ~55 km depending on the altimeter considered. This was made possible by recent advances in radar altimeter processing for both synthetic aperture radar (SAR) and low-resolution-mode (LRM) measurements, as well as improvements made to different stages of the DUACS processing chain. Firstly, the new adaptive and low-resolution with range migration correction (LR-RMC) processing techniques were considered for Jason and Sentinel-3 (S3A), respectively. They significantly reduce errors at short wavelengths, and the adaptive processing also reduces possible land contamination near the coast. Next, up-to-date geophysical and environmental corrections were selected for this production. This includes specific corrections intended to reduce the measurement noise on LRM measurements and thus enhance the observability at short wavelengths. Compared with the 1 Hz product, the observable wavelengths reached with the demonstration high-resolution product are reduced by up to one third, or up to half in the northeast Atlantic region. The residual noises were optimally filtered from full-rate measurements, taking into consideration the different observing capabilities of the altimeters processed. A specific data recovery strategy was applied, significantly optimizing the data availability, both in the coastal and open ocean areas. This demonstration L3 product is thus better resolved than the conventional 1 Hz product, especially near the coast, where it is defined up to ~5 km against ~10 km for the 1 Hz version. Multi-mission cross-calibration processing was also optimized with an improved long-wavelength error (LWE) correction, leading to a better consistency between tracks, with a 9–15% reduction in SLA variance at cross-overs. The new L3 product improves the overall consistency with tide gauge measurements, with a reduction in SLA differences variance by 5 and 17% compared with the 1 Hz product from the S3A and Jason-3 (J3) measurements, respectively. Primarily intended for regional applications, this product can significantly contribute to improving high-resolution numerical model output via data assimilation. It also opens new perspectives for a better understanding of regional sea-surface dynamics, with an improved representation of the coastal currents and a refined spectral content revealing the unbalanced signal.
影响因子：
16.6
作者：
Su Z;Wang J;Klein P;Thompson AF;Menemenlis D
通讯作者：
Menemenlis D