利用 SWOT 宽刈幅测高数据提升海洋重力场精度:与传统测高卫星的比较分析

于道成, 黄金维, 祝会忠, 罗佳, 袁佳佳

于道成, 黄金维, 祝会忠, 罗佳, 袁佳佳. 利用 SWOT 宽刈幅测高数据提升海洋重力场精度:与传统测高卫星的比较分析[J]. 武汉大学学报 ( 信息科学版). DOI: 10.13203/j.whugis20240120
引用本文: 于道成, 黄金维, 祝会忠, 罗佳, 袁佳佳. 利用 SWOT 宽刈幅测高数据提升海洋重力场精度:与传统测高卫星的比较分析[J]. 武汉大学学报 ( 信息科学版). DOI: 10.13203/j.whugis20240120
YU Daocheng, HWANG Jinway, ZHU Huizhong, LUO Jia, YUAN Jiajia. Enhancing Marine Gravity Field Precision Using SWOT Wideswath Altimetry Data: a Comparative Analysis with Traditional Altimetry Satellites[J]. Geomatics and Information Science of Wuhan University. DOI: 10.13203/j.whugis20240120
Citation: YU Daocheng, HWANG Jinway, ZHU Huizhong, LUO Jia, YUAN Jiajia. Enhancing Marine Gravity Field Precision Using SWOT Wideswath Altimetry Data: a Comparative Analysis with Traditional Altimetry Satellites[J]. Geomatics and Information Science of Wuhan University. DOI: 10.13203/j.whugis20240120

利用 SWOT 宽刈幅测高数据提升海洋重力场精度:与传统测高卫星的比较分析

基金项目: 

国家自然科学基金( 42404103, 42030109, 42074012, 42174017)

辽宁省“兴辽英才计划”项目资助(XLYC2203162)。

详细信息
    作者简介:

    于道成,博士,副教授,主要研究方向为卫星测高反演海洋重力场。yudaocheng@lntu.edu.cn

    通讯作者:

    祝会忠,博士,教授。zhuhuizhong@lntu.edu.cn

Enhancing Marine Gravity Field Precision Using SWOT Wideswath Altimetry Data: a Comparative Analysis with Traditional Altimetry Satellites

  • 摘要: SWOT(Surface Water and Ocean Topography)宽刈幅测高卫星以前所未有的空间分辨率和精度获取海面高度信息,为提升现有海洋重力场的精度和分辨率带来机遇。但是,目前关于 SWOT 反演海洋重力场的研究较少,尤其缺乏基于 SWOT 构建的海洋重力场精度的量化结果,本文基于 SWOT模拟数据,研究 SWOT 在解算垂线偏差分量和反演海洋重力异常方面的潜力。模拟了观测精度为 1.4cm、空间分辨率为 2 km×2 km 的 SWOT 宽刈幅海面高观测值, 同时模拟了传统测高卫星 Jason-2 和Cryosat-2 数据,对比研究 SWOT 较传统测高卫星在反演海洋重力场方面的优势。利用最小二乘配置法(least-squares collocation, LSC)和加权最小二乘平差法(weighted least-squares adjustment, WLSA)解算垂线偏差南北向和东西向分量,并利用逆 Vening-Meinesz 法反演重力异常。在 SWOT 数据模拟过程中获取的垂线偏差分量和重力异常的“真值”用于评估计算结果的精度。为充分利用 SWOT 宽刈幅测高特性,将 SWOT 二维数据分解为沿轨迹和垂直轨迹方向的一维数据。研究结果表明, LSC法解算的垂线偏差分量精度优于 WLSA 法;平均多周期 SWOT 数据可有效削弱观测误差; SWOT 沿轨迹数据有利于解算南北向分量,而垂直轨迹数据有利于解算东西向分量。在本研究区域,融合Jason-2 和 Cryosat-2 数据解算的 1′×1′垂线偏差南北向与东西向分量的精度均约为 3 microrad, 反演的 1′×1′海洋重力异常精度为 4.7 mgal。而 SWOT 将垂线偏差分量的精度提升至 0.7 microrad,并将重力异常精度提升至 1 mgal。研究表明,相较于传统测高卫星, SWOT 宽刈幅测高卫星在提升海洋垂线偏差和重力场精度方面具有显著优势。
    Abstract: Objectives: Surface Water and Ocean Topography (SWOT) mission, a wide-swath altimeter satellite, measures sea surface heights (SSHs) with unparalleled spatial resolution and precision, offering new opportunities to enhance the precision and resolution of the existing marine gravity fields. However, there is currently limited research on recovering marine gravity fields from SWOT, particularly with respect to quantitative assessments of the accuracy of SWOT-derived marine gravity field. This study investigates the potential of SWOT in determining deflection of the vertical (DOV) and deriving marine gravity anomalies based on simulated SWOT data. Methods: In the northern South China Sea around Dongsha Island, we generate the high-wavenumber SSH components using multi-beam depths based on the residual depth model principle, compensating for the losing high-frequency signals of the DTU21MSS model. Then we simulate wide-swath SWOT SSH observations with 1.4cm precision and 2 km×2 km spatial resolution. In order to explore the advantages of SWOT in recovering marine gravity field over the conventional nadir-looking altimeter satellites, we also simulate SSH data for Jason-2 and Cryosat-2. To make the most of SWOT’s wide-swath altimetry nature, we separate two-dimensional SSHs into along- and cross-track directions. We use least-squares collocation (LSC) and weighted least-squares adjustment (WLSA) to estimate the north and east components of DOV and derive marine gravity anomalies using inverse Vening-Meinesz formula. The “true values” of DOV components and gravity anomalies are computed within the simulation of SWOT data to evaluate the precision of the results. Results: The LSC method outperforms WLSA in estimating the DOV components. Averaging multi-cycle SWOT data efficiently suppresses observation errors. SWOT along-track data are beneficial for estimating the north components of DOV, while the cross-track data are useful for resolving the east components. In the study area, the precision of both the north and east components of DOV estimated from the merged Jason-2 and Cryosat-2 data is about 3 microrad, thereby deriving 1′×1′ gravity anomalies with 4.7-mgal precision. Using SWOT data, the precisions of the two DOV components and gravity anomalies improve to 0.7 microrad and 1 mgal, respectively. Conclusions: Compared to conventional altimeters, the SWOT wide-swath altimetry significantly improves the accuracy of marine DOV and gravity fields.
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  • 收稿日期:  2024-09-20

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