Gravity field inversion from China ocean altimetry tandem satellites data and performance analysis

doi:10.11947/j.AGCS.2025.20240340

Abstract

Abstract:

In this paper, we use the sea surface height data of the China ocean altimetry tandem satellites (COATS) and the SWOT satellite of the United States to compute the disturbed gravity vector (vertical deflection and disturbed gravity). The abnormal data of COATS satellite are filtered by using the regional inverse distance weighted iterative method, and the outliers are eliminated effectively. According to the characteristics of the two-satellite tandem mode and wide-swath mode, a method based on multi-directional sea surface gradient estimation is adopted to solve the grid vertical deflection and the disturbed gravity in the sea area is retrieved. The calculation of the Western Pacific region shows that the COATS satellite makes full use of the near real-time sea surface height in the cross-orbit direction in the calculation of the vertical deflection, and can realize the calculation of the local 1′×1′ vertical deflection in the tandem-following mode, compared with the 1′×1′ vertical deviation calculated by EIGEN-6C4 model, the standard deviation of north-south and east-west component is respectively 1.65″ and 2.3″. SWOT satellite is the first wide-swath interferometric altimetry satellite in the world. The accuracy of its north-south component and east-west component is consistent with that of EIGEN-6C4 model, the standard deviation of north-south and east-west components is about 1.8″, which fully reflects the advantage of uniform observation of wide-swath. Compared with the gravity data of SIO 32.1, the standard deviation of gravity anomaly respectively derived from COATS 5′×5′, SWOT 1′×1′ and two satellite fusion 1′×1′ data is 6.4, 5.2 and 4.9 mGal. Considering that COATS and SWOT are currently the satellites which truly achieve 1′×1′ sea surface height surveying, the combined COATS and SWOT satellite data will get more intensive vertical deflection and disturbed gravity, which will further improve the precision of the gravity field in the sea area.

Key words: ocean satellite altimetry, COATS satellite, SWOT satellite, vertical deflection, gravity disturbing

CLC Number:

P223

Zhenhe ZHAI, Zhongmiao SUN, Jian MA, Bin GUAN, He HUANG, Mingda OUYANG, Lingyong HUANG, Zhiyong HUANG, Xingchen PAN, Shigeng YUAN, Shengli LIU, Sen LIU. Gravity field inversion from China ocean altimetry tandem satellites data and performance analysis[J]. Acta Geodaetica et Cartographica Sinica, 2025, 54(4): 714-724.

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误差改正项	改正模型
电离层误差	Ku/C双频改正
干对流层误差	Saastamoinen（1972）模型
湿对流层误差	三频校正辐射计
海洋潮汐	FES2014b模型
固体潮汐	Cartwright and Taylor 1973模型
极潮	IERS Equilibrium模型，Wahr（1985）模型
逆气压改正	Wunsch and Stammer（1997）模型
海况偏差改正	NPSSB模型

比较类型	格网大小	最大值/（″）	最小值/（″）	差值均值/（″）	标准差/（″）	参与评估的数量
南北	1′×1′	11.36	－10.28	0.11	1.65	82 534
分量	5′×5′	11.13	－9.36	0.10	1.51	14 400
东西	1′×1′	28.42	－16.70	0.28	2.37	82 534
分量	5′×5′	24.86	－16.34	0.23	2.28	14 400

比较类型	格网大小	最大值/（″）	最小值/（″）	差值均值/（″）	标准差/（″）	参与评估的数量
南北	1′×1′	37.75	－21.89	0.08	1.73	359 062
分量	5′×5′	15.64	－24.39	0.07	1.69	14 400
东西	1′×1′	38.62	－40.31	0.04	1.87	359 062
分量	5′×5′	21.64	－20.31	0.03	1.52	14 400

比较类型	赋权原则	格网大小	最大值/（″）	最小值/（″）	差值均值/（″）	标准差/（″）	参与评估的数量
南北	等权	1′×1′	47.19	－70.08	0.14	1.84	360 000
分量	不等权	1′×1′	47.18	－69.58	0.15	1.72	360 000
东西	等权	1′×1′	59.41	－67.62	0.09	1.81	360 000
分量	不等权	1′×1′	58.72	－63.65	0.09	1.81	360 000

比较数据	格网大小	最大值/mGal	最小值/mGal	差值均值/mGal	标准差/mGal	参与评估的数量
COATS&SWOT	5′×5′	91.18	－59.85	0.02	5.07	14 400
COATS&SWOT	1′×1′	59.84	－59.97	0.01	4.96	360 000
EIGEN-6C4	1′×1′	59.78	－49.05	－0.06	8.09	360 000