###### Abstract  
Haiyang-2 (HY-2) missions have accumulated sea surface height (SSH) observations on a global scale for more than 10 years. Four satellites, HY-2A, HY-2B, HY-2C and HY-2D, provide even but differently distributed data, which play a complementary role in marine gravity studies with other missions. Therefore, this paper evaluates the performances of HY-2 altimetric data in marine gravity modeling from the following four perspectives: SSH accuracy, geoid signal resolution ability, vertical deflections and gravity anomaly. First, the centimeter-magnitude accuracy level of HY-2 data is proved by analyzing SSH discrepancies at crossover points within a certain time limit. Second, the spectral analysis of repetitive along-track data sequences in a time domain shows a geoid resolution range from 18 to 24 km. Taking HY-2 exact repeat missions (ERM), for example, the resolution could be remarkably enhanced by stacking repetitive cycles. Third, validation with an XGM2019 model showed that vertical deflections were reliably computed for all HY-2 missions, but HY-2A performed slightly worse than the other HY-2 missions. Meanwhile, HY-2C and HY-2D with a ~66\({}^{\circ}\) orbital inclination obviously had an improved ability to capture east-west signals compared to HY-2A and HY-2B. Finally, we constructed global marine gravity results based on three input datasets, HY-2 dataset only, multi-satellite dataset without HY-2 and multi-satellite dataset with HY-2. Validations were performed using published models and shipborne gravimetric data. The results showed that the HY-2 dataset is capable of improving marine gravity anomaly recoveries and that the accuracy of NSOAS22 with incorporated HY-2 data is comparable to DTU21 and SS V31.1. Furthermore, HY-2 observations should not be the only input dataset to construct a 1\({}^{\prime}\times\) 1\({}^{\prime}\) resolution marine gravity model. H 2 2022 29 August 2022 29 August 2022 29 August 2022 29991 15 September 2022 2991 15 July 2  
in gravity recovery, either by adopting waveform retrackers or incorporating updated data [8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18]. Marine gravity can be modelled directly from the geoid heights or vertical deflections. The geoid heights are obtained by the difference between SSH measurements and the corrections of dynamic ocean topography. The SSH should be accurately determined by introducing extra procedures, such as a crossover adjustment, to suppress the effect of radial orbit error. In contrast, vertical deflection can be calculated from the geoid-height slopes. The along-track difference procedure in calculating slopes has the advantage of constraining long-wavelength error components. Consequently, the crossover adjustment is unnecessary for the slopes-based method [19] and several corrections are negligible, dry tropospheric path delay, solid earth tide correction and the geocentric polar tide effect [20]. In addition, the slopes-based method is more sensitive to seafloor topography and performs better when calculating marine gravity field elements over the open ocean. Therefore, this study aimed to evaluate the performance of HY-2 series data from the perspective of the slopes-based method. Currently, China's ocean dynamic environment monitoring network has been established with a series of successfully launched satellite missions. Among them, HY-2A has provided reliable SSH observations with uniform data coverage on a global scale for more than 10 years, especially data with denser geographical distribution for the latest geodetic mission (GM), since March 2016. HY-2B is performing an exact repeat mission and has collected more than 3 years of high-quality measurements along ground tracks that are similar to those of HY-2A. The orbital inclination of \(\sim\)99\({}^{\circ}\) has a larger global coverage scope, which is closer to the north and south poles. In addition, HY-2C and HY-2D were successfully launched into pre-designed \(\sim\)66\({}^{\circ}\) inclined orbits.