Improved latitude difference method for calculating crossover point position from wide-swath measurement data

doi:10.11947/j.AGCS.2026.20250341

Abstract

Abstract:

The wide-swath sea surface height (SSH) data obtained by the SWOT satellite are of great significance for improving the resolution of the ocean gravity field. Compared with traditional altimeter data, wide-swath two-dimensional data increases the time consumption for calculating crossover points. Therefore, the improved latitude difference method for calculating crossover points is proposed. The size and position of the crossover area are determined based on different latitudes, and then crossover point position within this area are calculated. Compared with other methods, the proposed approach identifies crossover points accurately while requiring only 20% of the time needed by the latitude difference method. In addition, the accuracy of SWOT SSHs was analyzed by using the SSH discrepancies at crossover points. Compared with Level 2 products, Level 3 SSH products show an accuracy improvement of more than 90%. The accuracy of Level 2 SSH products is lower at the edge of the crossover area than elsewhere, whereas Level 3 products exhibit no obvious spatial distribution pattern within the crossover area. Overall, the improved latitude difference method effectively improves the calculation efficiency of the crossover point.

Key words: wide-swath, SWOT, along-track, cross-track, crossover points

CLC Number:

P228

Chengcheng ZHU, Zhen LI, Jinyun GUO, Maosheng ZHOU, Wanqiu LI. Improved latitude difference method for calculating crossover point position from wide-swath measurement data[J]. Acta Geodaetica et Cartographica Sinica, 2026, 55(4): 673-683.

Figures/Tables 10

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交叉点类型	方法	交叉点个数	时间/s	参与计算点数
平行轨道交叉点	纬度做差法	632 260	12 988	2 885 293 196
	基于限定区域的纬度做差法	632 260	2051	671 824 167
	格网法	1 640 474	1332	—
垂直轨道交叉点	纬度做差法	613 596	5096	106 962 011
	基于限定区域的纬度做差法	613 596	1060	99 019 219
	格网法	1 640 474	1332	—