verified the feasibility of deriving high spatial resolution monthly marine time-variable gravity anomaly from CryoSat-2 altimetry data. However, there may be no data within the window when the calculation window was less than 60\({}^{\prime}\). Therefore, despite the resulting grid resolution for the monthly marine time-variable gravity anomaly being 3\({}^{\prime}\), a 60\({}^{\prime}\) calculation window was used due to insufficient data from the radar altimeter, leading to a poor overall resolution [26]. The spaceborne Global Navigation Satellite System Reflectometry (GNSS-R) is a passive remote sensing technique that can receive multiple reflected signals from GNSS satellites simultaneously, covering wide swathes. This allows for advantages such as large data volume, low power consumption, low cost for constellation formation, and rapid global coverage and revisiting capabilities [27]. Figure 1 shows the diagram of spaceborne GNSS-R observations. The concept of utilizing GNSS reflections for remote sensing was initially proposed by [PERSON] in 1988 [28] and later expanded by [PERSON] in 1993 with the PARIS concept (Passive Reflectometry and Interferometry System), which combines GNSS direct and reflected signals for altimetry [29]. At present, multiple spaceborne GNSS-R missions are in orbit [30; 31; 32; 33; 34; 35], and have been successfully applied in various fields such as sea surface wind speed [36; 37], sea ice [38; 39], and soil moisture [40; 41]. Sea surface height (SSH) altimetry is one of the most promising and challenging applications of GNSS-R, which can complement existing technologies such as radar satellites [42]. However, spaceborne GNSS-R altimetry technology still faces many challenges in practical applications. On one hand, most existing Spaceborne GNSS-R missions do not specifically target SSH altimetry; the altimetry accuracy is relatively poor due to the use of low bandwidth signals [43; 44; 45]. On the other hand, although carrier-phase altimetry experiments on PETY and Spire satellites have achieved centimeter-level precision, the stringent observation conditions and insufficient effective observation rates remain significant challenges [46; 47; 48; 49]. The spaceborne GNSS-R interferometric processing technique, proposed by [PERSON] in 2011, is currently considered to be the most feasible spaceborne altimetry mode for spaceborne GNSS-R altimetry. By incoherently integrating power waveforms from multiple samples, the proposed PARIS IOD and Operational spaceborne GNSS-R missions can achieve decimeter-level sea surface height measurements with a 100-km along-track spatial resolution [50]. Subsequent studies have confirmed the stable performance of spaceborne GNSS-R interferometric altimetry in both accuracy and observation efficiency [51; 52]. Meanwhile, the European Space Agency (ESA) proposed the GEROS-ISS mission [53], which, although not yet implemented, has significantly advanced GNSS-R interferometric altimetry. In 2016, [PERSON] introduced the \"Cookie\" satellite constellation concept, analyzing its potential for networked observations [27]. Additionally, the feasibility of near real-time target detection from a constellation of GNSS-R has been demonstrated [54],  
Figure 1: Diagram of spaceborne GNSS-R observations. offering even better temporal resolution than SWOT in mesoscale ocean observations [55]. This technology has shown significant potential for ocean circulation monitoring, positioning it as a valuable complement to traditional radar altimetry [56]. Furthermore, scholars also have pointed out that GNSS-R SSH altimetry products will become an important data source for global marine gravity anomaly inversion [57; 58]. However, detecting short-wavelength marine gravity fields requires higher altimetry spatial resolution, yet increasing the GNSS-R along-track spatial resolution reduces the number of incoherent integrations, thereby decreasing altimetric accuracy. In 2018, [PERSON] et al.